tag:blogger.com,1999:blog-88834691420012874562024-03-13T06:13:23.003-07:00CBAC Forecaster's BlogCB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.comBlogger31125tag:blogger.com,1999:blog-8883469142001287456.post-90557698820082310552017-03-28T10:10:00.001-07:002017-03-28T10:10:11.040-07:00Welcome Ben Pritchett as the new ED and Lead forecaster for CBAC!<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.8px;">
<span style="font-size: 12.8px;">It comes with a heavy heart to announce I'm moving on from the Crested Butte Avalanche Center to take on a new role as the director of the Flathead Avalanche Center. I'm looking forward to an opportunity for personal and professional growth in Montana. I'm grateful for the strong sense of community here that has made this place my home, both in town and in the backcountry. Our mountain town is unique in how our backcountry users respect and look out for each other, and this energy is what has helped our little avalanche center thrive and grow to what it is. Your observations, support, and donations help to make the CBAC one of the best forecast centers in the country. Thank you for that, Gunnison Valley, and I hope that is something that won't change here as the backcountry evolves and becomes more crowded.</span></div>
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I'm excited to announce our new executive director and lead forecaster: Ben Pritchett. Ben brings a broad skill-set and diverse experience in the avalanche industry to the CBAC. In the past 12 years, Ben has served as the program coordinator for AIARE and avalanche education coordinator for the CAIC, gaining valuable experience working with backcountry users, educators, and forecasters around the country. Ben is a former forecaster for the CBAC and leads the forecasting program for the Grand Traverse. He also owns and runs a backcountry guiding business here in Crested Butte. Ben's industry connections and local understanding of our terrain, weather, and snowpack will contribute to the quality of our forecast products.</div>
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<tr><td class="tr-caption" style="text-align: center;">Ben at the 2017 Grand Traverse</td></tr>
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<br />Over the past 5 years, I have poured my heart into making this center the best it could be. One of the hardest parts about leaving the CBAC was my sense of investment here and the fear of leaving the center high and dry on my way out. The folks at the Flathead Avalanche Center were patiently willing to negotiate for a delayed start date which helped us conduct a thorough interview and hand-off process, and I'm glad we landed Ben. Evan and Ian are two of the most dedicated and passionate forecasters I've had the pleasure of working with, and they are both planning on returning next year. We brought on a new development director this past fall, Karen Williams, who has been working with us to improve our fundraising and outreach. And with Ben joining the team, I know now that the CBAC is in good hands moving towards a promising future with the goal of educating our community and saving lives from avalanche hazards. </div>
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Sincerely,</div>
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Zach Guy </div>
CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com5tag:blogger.com,1999:blog-8883469142001287456.post-46114758113396756322017-02-07T08:30:00.000-08:002017-02-07T08:50:05.905-08:00A letter of protest to surface hoar<div class="MsoNormal">
Dear Surface Hoar,</div>
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First you <a href="http://cbavalanchecenter.org/surface-hoar/">bedazzled us with your shimmering feathers</a>, glistening under the cloud layers that brought our unusual
surface hoar event back in mid-January.
You are fragile and don’t belong in Colorado’s windy and sunny
environment. We thought to ourselves, “You’re
a long shot, surely you won’t survive.”
But somehow you did. Things
started to go downhill on January 19<sup>th</sup>, when you got buried beneath
a storm that came without wind, against the odds.</div>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-UyXp5O1C7W0/WJnvBJHvq-I/AAAAAAAACXU/N6Uf06sAeIsJdxDv8qvRPJ7jraEboy_DQCLcB/s1600/Picasa%2B3%2B272017%2B85734%2BAM.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="270" src="https://1.bp.blogspot.com/-UyXp5O1C7W0/WJnvBJHvq-I/AAAAAAAACXU/N6Uf06sAeIsJdxDv8qvRPJ7jraEboy_DQCLcB/s400/Picasa%2B3%2B272017%2B85734%2BAM.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Unusual cloud layers and unusually widespread surface hoar layer in mid January. Photo courtesy of MSF Films</td></tr>
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Then more snow came, and it formed
a soft slab above you, and your behavior started getting erratic through the last week of January. We saw lots of natural avalanches, we saw
avalanches breaking in dense aspen groves and on low angle slopes, and we saw
slides remotely triggered from flat terrain. </div>
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<span style="text-align: start; text-indent: 48px;">Video demonstrating the touchy and unusual avalanche behavior in late January.</span></div>
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It has been 2 weeks since the last storm, and we have heard about slides triggered on you almost every single day, either in our zone or our neighboring Aspen zone. <span style="text-indent: 0.5in;">There were a number of <a href="http://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=45250&view=public">close calls</a> and <a href="http://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=45254&view=public">partial burials</a> on the Aspen side. </span></div>
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<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-c5IHbHcBzIw/WJn0H9t6fJI/AAAAAAAACX0/VqzOfqAcc1kHiDhyDJFQLJTJ2af9EGAKwCLcB/s1600/16387019_1097197810390346_7188491251514544435_n.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://4.bp.blogspot.com/-c5IHbHcBzIw/WJn0H9t6fJI/AAAAAAAACX0/VqzOfqAcc1kHiDhyDJFQLJTJ2af9EGAKwCLcB/s400/16387019_1097197810390346_7188491251514544435_n.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A slide on Mt. Emmons that caught a skier off guard.</td></tr>
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<span style="text-indent: 0.5in;"> Things have started to quiet down this past week, and travelers are starting to let their guard down.</span><span style="text-indent: 0.5in;"> </span><span style="text-indent: 0.5in;">But with more snow on the way this week, we can’t trust you and your unruly and dangerous behavior. It will become more sporadic and less predictable.</span></div>
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Video explaining our current snowpack structure on northerly/easterly aspects</div>
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I can’t recall the last time we had
someone like you as widespread and troublesome in our snowpack. Granted, a lot of things have changed in the past
few weeks for the better, and we are thankful for that. A lot of slopes have flushed. Winds have blasted you and their overlying
slabs away in places. The sun has capped
the snowpack with a stout crust on other slopes. So now you are lurking on fewer slopes, but
now the slabs above you will be growing thicker and more dangerous, and you will become more volatile again as more snow and wind prod at you. We will see skiers and snowmobilers recreate
on a lot of slopes with no apparent sign of problems from you, and our focus will be on freshly formed but manageable storm instabilities. But then somewhere you will
react harshly as you buckle under increasing pressure, or someone pokes your small feathers on the wrong slope, and it will be bad news for everyone involved. We know where you are
most likely to be bothered, and that happens<span style="text-indent: 0.5in;"> to be our favorite riding areas,
northerly and easterly aspects near and below treeline. But we can't know for sure where or when you will strike next. That scares us. </span></div>
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<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-W322NBGa1As/WJnyE-0XdoI/AAAAAAAACXk/o8Ca0a-UZBM4W280EcB4ATA30jzkTsUfQCLcB/s1600/20170130_rose%2B%25281%2529.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center; text-indent: 0px;"><img border="0" height="300" src="https://2.bp.blogspot.com/-W322NBGa1As/WJnyE-0XdoI/AAAAAAAACXk/o8Ca0a-UZBM4W280EcB4ATA30jzkTsUfQCLcB/s400/20170130_rose%2B%25281%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Most of the persistent slab avalanche activity in late January was on surface hoar. <br />
Read <a href="http://cbavalanchecenter.org/13017-avalanche-rose/">this observation</a> for some caveats to this diagram. </td></tr>
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<span style="text-indent: 0.5in;"> At the CBAC, we ask that you resign from causing problems in our snowpack, and move back to Canada, where you belong. </span></div>
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Sincerely, <o:p></o:p></div>
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Zach Guy<o:p></o:p></div>
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<span style="text-indent: 0.5in;">Director of CBAC</span></div>
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-61257789301855924902017-01-10T10:39:00.002-08:002017-01-10T20:05:59.904-08:00The New Year storm....already historic and still counting!<h2>
The New Year storm....already historic and still counting!</h2>
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By Zach Guy. CBAC Director/Lead Forecaster<br />
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<tr><td class="tr-caption" style="text-align: center;">Credit: Xavier Fane</td></tr>
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Since January 1st, the Gunnison Valley has been in the bullseye for heavy moisture streaming in from the Pacific. CBMR recorded 47" last week and 30" this week as of Tuesday morning. Irwin has recorded 87" out of this storm. We usually hear from billy barr by 7 a.m. for Gothic reports, but we're getting radio silence this morning, so I'm assuming that he's given up on digging and has turned to his stack of movies and chocolate barrs. But Gothic was at 86" yesterday. Holy Cow!</div>
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<tr><td class="tr-caption" style="text-align: center;">Credit: Chris Miller</td></tr>
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The first half of the storm came in pleasantly low density. On January 3rd, CBMR got 14" of 2% density snow. On the 4th, I came into the office to no snow, and by the time I left a few hours later, 10" had piled up, the kind that you clean your windshield with by blowing on it. On January 5th, Irwin got 20" of 5% snow, with steady 2"-3"/hour rates. </div>
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The next major pulse on January 9th was just the opposite: warm and wet. In a fantastic display of atmospheric absurdity, CBMR got 30" of dense snow. Schofield picked 3" of Snow Water Equivalent (SWE) in a mere 16 hours. (SWE is the water weight of the snow...multiply by about 12 or 15 to calculate how much snow fell for average conditions). It felt like I had just gotten out of the shower when I got back from the field to investigate a 3 foot slide that ran naturally across Kebler Pass Road. Trail breaking was miserable, wallowing through thigh deep, upside-down heavy snow. I'm sure countless people pulled out their backs shoveling. The Crested Butte Community School closed for the first time since 1970. CBMR closed early due to safety concerns. I counted at least two emails from billy barr that started with "It's a mess". With the rain line hovering near town, roof avalanches were ripping out right and left. Winds have been howling.</div>
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Of course, we haven't had much in the way of visibility since then, and with few people traveling in the backcountry right now, observations have been limited. Two large slides ran across Kebler Pass Road, piling 8 feet of debris on the road. I caught just enough clearing to spot a slide that ran to ground near Red Ridge. A lot of the paths near town were still holding as of yesterday afternoon.<br />
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Now to the weather stats. Schofield Pass SNOTEL has been operating since 1985. As of Tuesday morning, the site has picked up 10.5" of SWE since New Year's. This storm has surpassed all but one major storm in the past 32 years. We have another major pulse arriving Tuesday night into Wednesday and continued stormy weather into the weekend. This could push us beyond the historical 1986 storm, which reached 13.5" of SWE. Yowza!!</div>
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<a href="https://1.bp.blogspot.com/-bdntxLxOq2w/WHUii71qo4I/AAAAAAAACP8/e8sSfsTFzxY3wPUH5R-HNl6ePRqS6cP8wCLcB/s1600/Capture.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="235" src="https://1.bp.blogspot.com/-bdntxLxOq2w/WHUii71qo4I/AAAAAAAACP8/e8sSfsTFzxY3wPUH5R-HNl6ePRqS6cP8wCLcB/s400/Capture.JPG" width="400" /></a></div>
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We have had avalanche warnings and high avalanche danger for 4 days of this storm. Tomorrow we trended to extreme danger, something I've never done in my 6 years here (We missed a day of extreme danger back in 2014). Extreme danger calls for a very unusual event: widespread natural avalanche activity D3 in size, with the potential for some natural avalanches D4 or greater in size. Avalanches will break trees and may include areas of mature timber. Avalanches will likely run full path through all elevation bands, thus we paint all elevations black. These types of events happen so rarely that they are incredibly tough for forecasters to predict. In the 5 storms shown above, all of them saw widespread natural activity, and with the exception of 2010, all of them saw long running avalanches to the valley. 2010 saw most avalanches run before they reached the volume capable of historic paths. This year, we don't have as pronounced of weak layers as in some years, but we're seeing an exceptional load that could break the camel's back: the volume is already there. We will see what data we have tomorrow and how the next pulse of snow and wind is shaping up. Either way, it is very dangerous in the backcountry right now.</div>
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Regardless of whether we are at high or extreme tomorrow or the following days, our travel advice is pretty simple during an avalanche warning. Just stay off of and out from under avalanche terrain: slopes steeper than about 30 degrees or low angle slopes connected to steeper terrain above. Most backcountry travelers know better than to jump into big alpine faces during this kind of storm, but it can be the sneaky or small avalanche paths that kill you. We are more worried about a shoveler getting buried in a roof avalanche, or a kid on the sledding hill, or a dog walker on Peanut Lake Road, or a commuter to Irwin during storms like this. Our snowpack is shaping up to be a deep and strong one this year, so let's give it its due time to recover from this historical storm, and then let's enjoy a great winter ahead! And be sure to thank your local ski patrollers for their tough and dangerous work to reduce the risk of avalanches at CBMR. There have been two patrollers caught and carried in large slides this week. Those guys and gals hang it out there to get terrain open for you.</div>
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com5tag:blogger.com,1999:blog-8883469142001287456.post-27630882559412557792016-12-12T09:05:00.003-08:002016-12-13T05:51:52.098-08:00<span style="font-size: x-large;">Back in the flow. Zach Guy, CBAC Director</span><br />
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The Western U.S. is coming out of a long drought and the atmospheric snow guns have finally replaced the artificial ones that were building our ski area’s snow base. With snow comes avalanches. There were two avalanche fatalities in the West over the weekend: a <a href="http://www.rgj.com/story/life/outdoors/2016/12/11/details-emerge-avalanche-buried-mt-rose-skier/95300456/">skier in closed terrain in Mt Rose Ski Tahoe</a> on Saturday, and <a href="http://avalanche.state.co.us/caic/acc/acc_report.php?acc_id=618&accfm=rep">a backcountry skier near Cooke City, MT</a> on Sunday. We send our sincere condolences to all of those affected by these tragedies. Here in Colorado, there has been a stroke of divine luck, with a number of multi-party burials that resulted in profound learning lessons, rather than fatalities. A trio of skiers in Butler Gulch, near Berthoud Pass, <a href="http://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=43084">were all caught and buried</a> on Saturday. Two of them were only partially buried and were able to rescue the third. On Sunday, <a href="http://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=43164">a skier was caught in a slide</a> near Red Mountain Pass and <a href="http://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=43169">two snowmobilers were fully buried</a> but rescued by their group near Steamboat. On Monday, a snowmobiler was <a href="http://cbavalanchecenter.org/snowmobiler-triggered-caught-and-buried-by-ps-avalanche/">buried near Crested Butte</a>. Needless to say, avalanche season is upon us.<br />
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The search area for the avalanche victim at Mt. Rose Ski Tahoe. Photo courtesy of Washoe County Search and Rescue.<br />
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The Elk Mountains have been in a favorable zonal flow pattern since December 6th. CBMR reported 18” of snow in the past week, and some of our backcountry areas have picked up almost twice that. More is on the way this weekend. Anytime we have periods of dry weather, especially early season, our snowpack develops weak layers. Once we start getting back into the storm track, those weak layers get loaded and stressed, creating avalanche concerns. Sometimes these avalanches can act in surprising or unique ways, like being triggered from long distances away or from flat terrain. <a href="https://www.youtube.com/watch?v=kzjmvn6qrOs&t=22s">This video</a> demonstrates the challenging nature of persistent slab avalanche problems, where there is a cohesive slab over a persistent weak layer.<br />
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A group of 3 skiers were buried in this slide in Butler Gulch, CO on Saturday. Photo courtesy of CAIC.<br />
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It is easy to get caught up in the powder frenzy this time of year. We’ve all been itching to arc those graceful turns down powder filled slopes or throttle through deep pillows and faceshots. But we need to draw a line and stay behind it. One of my mentors up in Montana recently discussed how taking one step back from the line is insufficient. “To ensure a lifetime in the mountains, it is a matter of taking three or four steps back.” The CBAC got an observation yesterday, reporting signs of instability, which concluded with: “Suspect a successful tour could have been had with proper navigation today, but the instabilities spooked us, especially while navigating unfamiliar terrain. We opted to head home.” I applaud that kind of decision making. There isn’t any kind of steep or deep powder run that exceeds the reward of returning home safe at the end of the day.<br />
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Snow profile showing unstable results near Crested Butte. 12/11/16<br />
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If you are new to the area or visiting, make sure you tune into our avalanche advisories at <a href="https://www.blogger.com/www.cbavalanchecenter.org">www.cbavalanchecenter.org</a>. Our forecast team has been in frenzy the last couple weeks to keep tabs on the state of the snowpack. On Sunday, after a big pulse of moisture plowed through the night before, we had all three of our forecast staff up three prominent drainages surrounding our town digging into and documenting the snowpack to help aid in your backcountry decision making. Use our website and <a href="http://cbavalanchecenter.org/category/2016-17-observations/">observations page</a> as a resource! Give those guys a pat on the back for their often stressful and sleep deprived work during the holiday season. You can just sense the anxiety in Havlick's voice in <a href="https://www.facebook.com/cbavalanchecenter/videos/vb.165777617859/10154657357287860/?type=2&theater">this video</a>, and I bet the poor guy hasn't done his laundry in 2 weeks now. And thank our ski patrollers at CBMR and respect roped off or closed terrain. Those guys and gals are working hard to mitigate avalanche hazards to get terrain open.<br />
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com3tag:blogger.com,1999:blog-8883469142001287456.post-43320581458904364072016-11-29T18:28:00.000-08:002016-11-29T18:32:55.365-08:00Thanksgiving and avalanches<span style="font-size: large;">Thanksgiving and avalanches. By Zach Guy</span><br /><br /><br /><a href="https://1.bp.blogspot.com/-61zzp4jwhMU/WD4ynSZFxuI/AAAAAAAAB-I/VlwSJM5L3sMXySf4T-6FY6F_K7waZiDKACLcB/s1600/andy%2521%2B%25281%2Bof%2B1%2529-3.jpg"><img border="0" src="https://1.bp.blogspot.com/-61zzp4jwhMU/WD4ynSZFxuI/AAAAAAAAB-I/VlwSJM5L3sMXySf4T-6FY6F_K7waZiDKACLcB/s400/andy%2521%2B%25281%2Bof%2B1%2529-3.jpg" /></a> <br />Shooting cracks are a sign that the snowpack might have taken a few too many scoops of mashed potatoes and stuffing. <br /><br />It has been a wonderfully warm and dry fall, which is hard to complain about. But if we can be brutally honest with the weather gods, fall really was starting to wear out its welcome, and we are happy to open the door to winter. There's nothing quite like surfing over powder, so it's time to dust off those skis, find your beacon, shovel, and probe, and start tuning into our daily avalanche reports. <br /><br />Early season skiing and riding comes with some challenges and risks. The snow coverage is still quite shallow, so striking rocks and logs are tough to avoid and they can end your season pretty quickly. My strategies include getting on the fattest skis I can find, riding like a gaper in the backseat, and using releasable bindings in case my tips dive under a log or rock. I've seen a few too many broken tib-fibs from early season riding. And of course, we all want to go to where the snowpack is deepest, which can open the doors to another scary threat: avalanches. This time of year, the slopes holding deep and continuous coverage often carry the greatest risk of triggering an avalanche. It is almost impossible to go through fall without a shallow, crusty, and faceting foundation forming on the ground. Then once we start building a deeper snowpack, it creates a persistent slab avalanche problem above these layers. <br /> <br /><br /><a href="https://1.bp.blogspot.com/-PBDbHKbqjJ4/WD40s1CkQTI/AAAAAAAAB-Q/B2s2xqar_cgdy5o7FmsfFw8oOXfLaOmTwCLcB/s1600/DSCN0992-001.JPG"><img border="0" src="https://1.bp.blogspot.com/-PBDbHKbqjJ4/WD40s1CkQTI/AAAAAAAAB-Q/B2s2xqar_cgdy5o7FmsfFw8oOXfLaOmTwCLcB/s400/DSCN0992-001.JPG" /></a> <br />Skier triggered slides in Red Lady Bowl <br /><br />I like analogies, so let's compare our current year's snowpack to your most recent Thanksgiving celebration. You probably avoided food all day, maybe even went for a turkey trot to work up an appetite in preparation for the big feast. A significant drought, indeed. That left you weak and frail, just like the lingering snowpack layers that survived our fall drought. Then once dinner time (i.e. winter time) rolled around, you started off at a decent pace. Snacked on some hor devoirs, some salad, maybe some of your Uncle's famous deviled eggs or your Grandma's bean dip. Our first few storms behaved in similar fashion, fairly small and steady loads, with a handful of isolated avalanches. Nothing too scary yet. Then it is dinner time: you go for the mash potatoes, stuffing, turkey, green bean casserole, and of course drown it all under gravy. Extra rolls? Why not? Whammo. That's a heavy load, just like our last storm, which dumped almost 2 feet in places. Both scenarios are dangerous. You could collapse on the couch just as easily as you could collapse those fragile weak layers near the ground. During and after the storm, we saw both natural and skier triggered avalanches, some quite large and surprisingly wide. As of Tuesday night, I'm expecting we'll see evidence of a lot more avalanche activity as we get better visibility over the next few days. So tread carefully out there, and check the avalanche report before you go out. So what's next for our snowpack? Does it reach for another plateful of mashed potatoes before slamming down some pumpkin pie and faceplanting onto the floor? Or does it slowly nibble at the leftover turkey and try to stay awake for family charades? Only the weather can dictate that one. But you can be the captain of your risks by making rational decisions and practicing your rescue skills. Is it a coincidence that this Friday night is our Annual Avalanche Awareness Night, with the theme "Human Factors and Decision Making"? Or that Saturday is our annual Beacon Brushup, a free and valuable opportunity to dial in your rescue skills for the winter? I think not. See you there! <br /><br /><a href="https://4.bp.blogspot.com/-zcBojWWDxlc/WD4145eHZFI/AAAAAAAAB-c/sA4Cut_5mykwJAmk2RtdeEe3Tu4ehbBMACLcB/s1600/2016AwarenessBBU_2016_web.jpg"><img border="0" src="https://4.bp.blogspot.com/-zcBojWWDxlc/WD4145eHZFI/AAAAAAAAB-c/sA4Cut_5mykwJAmk2RtdeEe3Tu4ehbBMACLcB/s400/2016AwarenessBBU_2016_web.jpg" /></a><br /><br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com2tag:blogger.com,1999:blog-8883469142001287456.post-51534916390528773492016-11-24T10:24:00.001-08:002016-11-24T10:24:55.917-08:00Human Factors and Decision Making<br />
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<b>Human Factors and Decision Making</b></h2>
By Zach Guy, CBAC Director<br />
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This year's theme to <a href="http://cbavalanchecenter.org/cbac-avalanche-awareness-night/">CBAC's Avalanche Awareness Night</a> on December 2nd, 2016 is "Human Factors and Decision Making". Almost all avalanche accidents are triggered by the victim or a member of their group. We are the ones who expose ourselves to avalanche risks, and often it is our own decision making that puts us into trouble.<br />
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Although humans have been pondering our methods of thinking and rationalizing for centuries, Ian McCammon has been instrumental in research in the avalanche industry. I was fortunate enough to have Ian as a course instructor and mentor for my AVPRO class about 7 years ago, and caught up with him to ask a few questions about human factors and decision making.<br />
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<tr><td class="tr-caption" style="text-align: center;">Ian McCammon. Photo courtesy of POWDER magazine.</td></tr>
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<span style="background-color: #9fc5e8;">Zach Guy</span>: Ian, you have a PhD in mechanical engineering, and a Master's in Material Science. In the avalanche world, you are well known for your research on human decision making. What inspired your shift in focus from physics towards psychology?<br />
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<span style="background-color: #b6d7a8;">Ian McCammon</span>: My own journey started years ago when a friend of mine died in an avalanche. Using tools from my engineering background, I searched for statistical trends in hundreds of past accidents and found that the circumstances of my friend’s death followed a pattern that repeated itself again and again: risk perception for certain groups was distorted under certain conditions.<br />
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<span style="background-color: #9fc5e8;">Zach</span>: In 2002, you published a <a href="http://www.snowpit.com/articles/traps%20reprint.pdf" target="_blank">paper on heuristic traps</a> and how these human factors affect our decision making and influence avalanche accidents. The acronym "FACETS" (Familiarity, Acceptance, Consistency, Experts, Tracks/Scarcity, and Social Facilitation) has been adopted by essentially every avalanche course around the country to introduce these human factors. My talk at Avalanche Awareness Night will dive into some of these factors and a close call that I had back in 2009. In your research or simply from personal experience since then, are there any other human factors that you think backcountry travelers should be aware of?<br />
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<span style="background-color: #b6d7a8;">Ian</span>: Fatigue is an important physiologic factor that influences our decision making. When you are tired, dehydrated, hungry, cold or just sucking air from a long ascent, it’s hard to judge hazards objectively. And just like the FACETS cognitive traps, fatigue is dangerous because people consistently underestimate how profoundly it can impair their judgement.<br />
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<span style="background-color: #9fc5e8;">Zach:</span> You developed some systematic tools to help backcountry travelers overcome our human biases, such as <a href="http://www.avalanche.org/moonstone/DecisionMaking/ObviousClues.McCammon.TAR25.2.pdf" target="_blank">ALPTRUTH</a> and <a href="http://www.snowpit.com/articles/lemons%20reprint%20copy.pdf" target="_blank">Lemons</a>. Do you have any other personal tips or strategies that you use in your ski tours for overcoming the inherent biases in the way our brains process information and make decisions?<br />
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<span style="background-color: #b6d7a8;">Ian</span>: ALPTRUTh was designed to do two things. First, it stops you at the cusp of a decision - it breaks the momentum that sometimes carries people into trouble. Second, it helps you see how your group’s decision will be viewed should an accident take place - a process called a pre-mortem. There are other ways to do this, and my hope is that new and better tools will emerge from research into this important area.<br />
Another strategy in addition to APLTRUTh is to choose your partners wisely. Choose people with the wisdom to stop the group's momentum at the right times and reconsider evidence and the opinions of the group. If they can do that, it’s going to be less frustrating and more effective to manage risk as a group.<br />
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<span style="background-color: #9fc5e8;">Zach</span>: Social media has exploded since your original research 15 years ago. We have a presenter who will be touching on this subject at Avalanche Awareness Night. With Facebook, Instagram, Youtube, etc., the entire internet is watching what we do in the backcountry. What is your take on the impact of social media on our decision making, and do you suggest or have any strategies for handling its potential influences?<br />
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<span style="background-color: #b6d7a8;">Ian</span>: This is a fascinating and worthy topic for research. I am glad you have a presenter exploring this subject. Some folks are choosing to literally create their social identities in near-real time as their decisions and outcomes are posted and amplified across an audience of friends and potential critics. An important question for each of us is how much are we willing to allow that unseen audience to shape our critical decisions.<br />
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<span style="background-color: #9fc5e8;">Zach:</span> Any parting words for our Colorado audience that recreates in the deadliest snowpack in the country?<br />
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<span style="background-color: #b6d7a8;">Ian</span>: To paraphrase Baltasar Gracian: Know your major weakness. If you do not understand it, it will rule you like a tyrant.<br />
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<span style="background-color: #9fc5e8;">Zach</span>: Thank you Ian for sharing your wisdom, and for your contributions to the avalanche industry.<br />
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Join us at CBAC's Avalanche Awareness Night for more great presentations on human factors and decision making. <br />
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<br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com1tag:blogger.com,1999:blog-8883469142001287456.post-22686598600310201712015-12-15T20:08:00.002-08:002015-12-16T06:58:58.480-08:00Backcountry Etiquette <div class="separator" style="clear: both; text-align: center;">
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By Zach Guy - CBAC Director</div>
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Backcountry recreation is a rapidly growing industry in the West, and equally rampant in our little valley. As the mountain regions around the U.S. becoming increasingly busy during the winter, there have also been an increase in close calls and conflicts between user groups pertaining to avalanche safety.</div>
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Several years ago, on an easily accessible peak near Teton Pass, a backcountry skier triggered a huge slab avalanche, upwards of 8 feet deep. The slide ran thousands of feet, plowing along a drainage that is a popular access and egress point for relatively safe tree skiing. Debris piles were monstrous, and the resulting public outcry was equally monstrous. You can read more about the Taylor Mountain slide <a href="http://www.tetonat.com/2012/01/24/taylor-mountain-avalanche/" target="_blank">here</a>. Similar issues have arisen in the Wasatch, some of the passes around Colorado, and more. As the backcountry becomes more crowded, our need for responsible etiquette increases. In most cases, it is to protect our fellow backcountry enthusiasts. But in some cases, we are jeopardizing the safety of the general public who is unknowingly walking or driving their car beneath the avalanche path that you are skiing or riding. </div>
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<tr><td class="tr-caption" style="text-align: center;">The slide on Taylor Mountain near Teton Pass. The skier was conducting an intentional ski cut, but the slide went much larger than expected. Photo courtesy of TetonAT.com</td></tr>
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<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white; color: #222222; font-family: "arial" , sans-serif; font-size: 12.8px;">Debris piles were 10-12 feet deep in the Coal Creek drainage, a launching and exit point for many backcountry skiers looking to get into relatively safe terrain. Photo courtesy of TetonAT.com.</span></td></tr>
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<span style="font-size: 12.8px;">At the CBAC, we have been hearing feedback that our community needs a reminder about backcountry etiquette. Even our small town has issues with over-crowding in the backcountry. Observers have noted multiple instances where groups of skiers descended upon another group climbing the same avalanche path. I've always been impressed with the attitude and etiquette of backcountry users in this community. We share observations of snowpack and avalanches, we look out for each other's interests while on slope, and we don't seem to hold the territorial or secretive attitudes that many ski towns around the U.S. have. That's one reason why I've chosen to live here. Lets not lose that consideration for our community in the backcountry as more people migrate to this great backcountry destination.</span><br />
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So what does backcountry etiquette mean? Simply put, be aware of your actions and their consequences in the backcountry, because they don't solely affect you. If you trigger an avalanche, will it affect someone down slope of you? Communicate with people you encounter on your tours; discuss your routes and how you can avoid crossing above or below each other. A few days ago, I found myself on top of the Anthracites on a powder day with over a dozen powder-starved locals eager to drop in. All of the groups did a great job of communicating and divying up the terrain so that we didn't all get bunched up on one avalanche path. If you see a group climbing up your intended descent route, wait for them or choose another route. Its simply not worth putting them in the line of fire. Cornice drops and ski cuts can be a great slope test, but are you absolutely sure that no one will be affected below you? Think about the size and possible extent of an avalanche that you could trigger. Under some conditions, a slide on Red Lady Bowl or above Peanut Lake Road or on Snodgrass could run across roadways of innocent commuters. And just as importantly, if you get injured or killed in a slide, the impacts reach far beyond just you. You have family members, friends, and community members that will be deeply impacted.</div>
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<tr><td class="tr-caption" style="text-align: center;">This is a natural avalanche that crossed Peanut Lake Road and the nordic track 2 winters ago.</td></tr>
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Winter is just underway here in the Crested Butte area as our shallow and weak snowpack is starting to get buried. We will undoubtedly see dangerous avalanche conditions developing once we see some big storms. Lets kick winter off right. Consider your safety and the safety of others by bringing an improved sense of backcountry etiquette to the Elk Mountains.</div>
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<br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com1tag:blogger.com,1999:blog-8883469142001287456.post-19626027746355197532015-02-13T15:52:00.001-08:002015-02-13T15:52:48.916-08:00Absurduary: A look at our warm and dry start to 2015.<div class="MsoNormal">
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<b><span style="font-family: Arial, sans-serif; line-height: 115%;">February 12,
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<span style="font-family: Arial, sans-serif;"><span style="line-height: 18.3999996185303px;">In the past few weeks, I’ve seen streams emerge from high elevation basins, sunny slopes melt back to complete dirt, and a migration of locals towards the desert for mountain biking or sun bathing. I’ve only lived in Crested Butte for four years, but this pattern seems so absurd for a high Rockies mountain town at 9,000 feet in elevation, that I dug into some historical weather to see how unusual this weather has been.</span></span></div>
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<span style="font-family: Arial, sans-serif;"><span style="line-height: 18.3999996185303px;">Since the New Year, we’ve been plagued by both snowfall drought and unseasonably warm temperatures. The temperatures have been the greatest anomaly this winter. billy barr in nearby Gothic has an exceptional record of temperatures and snowfall dating back to 1974 (www.gothicwx.org). As of Friday, February 12th, 17 out of our 43 days this year have seen record-breaking high temperatures. There have only been two days in February that didn’t break a temperature record, and we are currently going on 8 days in a row of record high temps. I expect the next two days will break records too. On February 6th, the temperature hit 52 degrees F, which was a full month earlier than we’ve ever seen temps reach into the 50’s. I think my brother in Florida is having a colder winter right now.</span></span></div>
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<tr><td class="tr-caption" style="text-align: center;">Looking towards Red Lady Bowl and some dirt slopes down lower. Last year on this date, I dug a pit on a similar slope as that dirt slope in the foreground and found a 2 meter deep snowpack.</td></tr>
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<span style="font-family: Arial, sans-serif;"><span style="line-height: 18.3999996185303px;">Snowfall droughts this time of year aren't quite as unusual as the temperatures we've seen. I looked at both Gothic snowfall and records from the town of Crested Butte, which date back to 1962. (http://www.crestedbutte-co.gov) In Crested Butte, where the average snowfall in January is 41.6”, we got 10.6” of snow last month. There have only been four other January’s that saw less snowfall in the past 52 years. February is off to a rough start as well, with only a few inches. If it makes you feel any better, the winter of ’76-’77 only saw a total of 3” of snow from December through February in Crested Butte. Too bad they didn't have fat bikes back then. Gothic has fared marginally better on snowfall. They saw 27” in January, which is 41% of average and the 8th lowest January on record. Gothic picked up 6” in February, which is on pace to come up at 21% of the 70” average for February. Thanks to a healthy November and December, Schofield Pass SNOTEL is sitting at 67% of mean (3rd lowest snowpack in its 30 year record), and the Mt. Crested Butte SNOTEL is at 80% of its mean.</span></span></div>
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<span style="font-family: Arial, sans-serif;"><span style="line-height: 18.3999996185303px;">As someone who loves the winter, I can’t help but feel gloomy over the past couple months. However, models keep hinting at a pattern change coming later this month or in March, for the warm and dry high pressure ridge to shift west and put us back into the storm track. We’ll see... And also worth noting, the horrible snow year of ’76 to ’77, which was the lowest on record at 61” in Crested Butte, was followed the next winter by the highest snowfall on record, at 381”. I’ll stick around next winter to see what happens!</span></span></div>
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<tr><td class="tr-caption" style="text-align: center;">Looking towards Mt. Crested Butte. Looks more like late April than early February.</td></tr>
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com1tag:blogger.com,1999:blog-8883469142001287456.post-79115312551469689042014-12-28T19:17:00.000-08:002014-12-28T19:29:19.945-08:00What are facets?<div style="-webkit-text-stroke-width: 0px; background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;">
By Zach Guy</div>
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CBAC Forecaster </div>
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If you've been reading our avalanche advisories lately, you've probably noticed we've been talking a lot about<span class="Apple-converted-space"> </span><span class="il">facets</span>. Last weekend, major winter storm slammed into our mountains, and we saw widespread avalanche activity, with<span class="Apple-converted-space"> </span><span class="il">facets</span><span class="Apple-converted-space"> </span>being one of the major culprits. So what is the deal with this snow grain type, how does it form, and why is it so problematic?</div>
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<span class="il">Facets</span><span class="Apple-converted-space"> </span>are a sugary-like snow grain. They glisten in the sun, bounce in your glove, and commonly make a noticeably soft or hollow layer in the snowpack. If you look at them under a magnifying glass, they have many flat edges, hence the name<span class="Apple-converted-space"> </span><span class="il">facets</span>. </div>
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<tr><td class="tr-caption" style="text-align: center;">Courtesy Photo</td></tr>
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There are several different ways that can cause snow grains to<span class="Apple-converted-space"> </span><span class="il">facet</span>, but they all share the same underlying physical process. <span class="Apple-converted-space"> </span><span class="il">Facets</span>form when water vapor moves quickly through the snowpack. Each particle gets handed off between grains, via sublimation and deposition, causing the grains to reconfigure into a more angular form. Strong temperature differences within the snowpack cause this water vapor relay. We can see<span class="Apple-converted-space"> </span><span class="il">facets</span><span class="Apple-converted-space"> </span>form early season when the ground is quite warm, there is a shallow snowpack, and the air gets cold, especially at night. This drives the water vapor upward through the snowpack causing it to<span class="Apple-converted-space"> </span><span class="il">facet</span>, or rot out. We also see a similar process occurring on top of the snowpack, called "near surface faceting." When we get warm days and cold, clear nights, the snow surface undergoes wild temperature swings, causing the same rapid water vapor movement. This process is expedited if the surface is composed of soft, low density snow, rather than stiff, hard, compacted snow. All of these ingredients have come together this winter. We have seen basal<span class="Apple-converted-space"> </span><span class="il">facets</span><span class="Apple-converted-space"> </span>form during the early season when our snowpack was shallow. Then, on December 1st, we got about 4" of new, low density snow, which was followed by two weeks of warm days and cold, clear nights. That surface snow metamorphosed into fragile, sugary grains, and we didn't get strong winds that can sometimes destroy that layer as it is forming. On December 13th, that near surface<span class="Apple-converted-space"> </span><span class="il">facet</span><span class="Apple-converted-space"> </span>layer was buried, and it is now under the weight of all the new snow that has fallen in the past 2 weeks.</div>
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<span class="il">Facets</span><span class="Apple-converted-space"> </span>form a type of layer in the snow coined as a "persistent weak layer." So once a layer of<span class="Apple-converted-space"> </span><span class="il">facets</span><span class="Apple-converted-space"> </span>gets buried by a slab of new or windblown snow, it makes for a weakness in the snowpack on which avalanches can fail. Worst of all, the weakness is long-lasting, so we can see avalanches fail on<span class="Apple-converted-space"> </span><span class="il">facet</span><span class="Apple-converted-space"> </span>layers weeks or months after they are buried. This means that we can see very large slabs of snow develop over the course of the winter before a<span class="Apple-converted-space"> </span><span class="il">facet</span><span class="Apple-converted-space"> </span>layer might finally give out, causing a huge avalanche. <span class="Apple-converted-space"> </span><span class="il">Facets</span><span class="Apple-converted-space"> </span>have a few other nasty tricks up their sleeves. If the layer is fairly continuous, it is so fragile that it can drive a failure very long distances across avalanche terrain. I've seen avalanches fail almost a mile wide on<span class="Apple-converted-space"> </span><span class="il">facet</span><span class="Apple-converted-space"> </span>layers!! If you can get the layer to collapse on flat terrain, it can propagate up a slope and cause an avalanche to release above you. So not only do these layers plague us for long periods of time, but they also behave in an unusual manner. Keep this in mind in upcoming weeks and months, now that we have several<span class="Apple-converted-space"> </span><span class="il">facet</span><span class="Apple-converted-space"> </span>layers buried in our snowpack. For more information or to get daily avalanche advisories, visit<span class="Apple-converted-space"> </span><a href="http://www.cbavalanchecenter.org/" style="color: #1155cc;" target="_blank">www.cbavalanchecenter.org</a>.<br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-iidZNYLXM30/VKDKEO8hqNI/AAAAAAAAAiw/R9XNU-19_1w/s1600/PPSledStop_121914%2B-%2BCopy.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-iidZNYLXM30/VKDKEO8hqNI/AAAAAAAAAiw/R9XNU-19_1w/s1600/PPSledStop_121914%2B-%2BCopy.jpg" height="225" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is a photo of a shallow slab that propagated impressive distances on the December 13th facet layer, near Purple Palace. Photo credit: Aaron Huckstep</td></tr>
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-10050597926913420912014-12-28T18:56:00.002-08:002014-12-28T18:57:50.794-08:00Ian's Weather Resources Current Data<br /><br />Surface:<br /><br /> http://weather.rap.ucar.edu/surface/<br /> https://avalanche.state.co.us/obs_stns/stns.php<br /> http://mesowest.utah.edu/cgi-bin/droman/mesomap.cgi?state=CO&rawsflag=3<br /> Schofield SNOTEL: http://www.wcc.nrcs.usda.gov/nwcc/site?sitenum=737<br /><br />Upper-air soundings:<br /><br /> http://weather.rap.ucar.edu/upper/<br /><br />Radar & Satellite:<br /><br /> http://www.weathertap.com ($84/yr, great mobile website as well)<br /><br />Discussions<br /><br /> NWS: http://www.nws.noaa.gov/view/prodsByState.php?state=CO&prodtype=discussion<br /> OpenSnow: http://opensnow.com/dailysnow/colorado<br /> CAIC: http://avalanche.state.co.us/forecasts/weather/zone-forecast/<br /> http://wasatchweatherweenies.blogspot.com<br /><br />Forecast Models: Twisterdata.com<br /><br />Top Center<br /><br />NAM = 84hr 12km resolution<br /><br />GFS = 384hr 27km resolution<br /><br />RAP = 18hr 13km resolution<br /><br />Left Side<br /><br />700mb = orographic wind direction<br /><br />500mb = vorticity<br /><br />300mb = jet stream<br /><br />Upper Right<br /><br />Clickable map = one forecast image<br /><br />Animated loop = all forecast images<br /><br />Compare models = toggle between each model<br /><br />dProg/dt = see the trend in the forecasts<br />Forecast Models: CAIC<br /><br /> High-resolution version of the NAM model<br /> Graphics: http://avalanche.state.co.us/forecasts/weather/model-forecasts/<br /> Points: http://avalanche.state.co.us/forecasts/weather/point-forecasts/<br /><br />Forecast Models: Weatherbell.com<br /><br /> Access to European model graphics and many other models. Fantastic data. $185/year<br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-87082020804498181302014-11-27T08:07:00.004-08:002014-11-29T08:57:06.611-08:00New Website: Avalanche Problems<span style="display: inline ! important; float: none; font-family: ProximaNovaRegular,sans-serif; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 18px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span style="font-family: Georgia,"Times New Roman",serif;"><span style="font-family: Arial,Helvetica,sans-serif;"><span style="font-size: small;">Zach Guy</span></span></span></span><br />
<span style="display: inline ! important; float: none; font-family: ProximaNovaRegular,sans-serif; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 18px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span style="font-family: Georgia,"Times New Roman",serif;"><span style="font-family: Arial,Helvetica,sans-serif;"><span style="font-size: small;">Forecaster, CBAC </span></span> </span></span><br />
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<span style="font-family: Arial,Helvetica,sans-serif;">By now, you've probably noticed the CBAC has had a bit of a make-over. We have spent over a year designing, researching, redesigning, and coding our new website, which we launched this week. We were operating on an old dinosaur of a web platform and it was time for a new site that matched the current state of the e-world. This new site has improved graphics, higher resolution imagery, more user friendly from our end and yours, an improved observations platform, a format that is more consistent with avalanche centers nation-wide, and some additional forecasting tools which you can use to make safer decisions in the backcountry. Bear with us as we work through the kinks and strive to improve the functionality of the site. </span><br />
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<span style="font-family: Arial,Helvetica,sans-serif;">Now let's jump into a key element of our daily forecasts: the avalanche problem. The reason we put a lot of focus on avalanche problems is because the flavor of the avalanches we expect to encounter can be more influential in our terrain and risk management than a given danger rating. For example, not all Moderat danger ratings are created equal. I move through terrain and make snowpack assessments very differently for a Moderate danger when the only concern is wind slabs, versus a moderate danger involving deep persistent slabs. The Utah Avalanche Center just published a new tutorial on avalanche problems; its worth a look. <a href="http://utahavalanchecenter.org/avalanche-problems-tutorial" target="_blank"> http://utahavalanchecenter.org/avalanche-problems-tutorial</a>. The CAIC also defines each problem <a href="http://avalanche.state.co.us/forecasts/help/avalanche-problems/" target="_blank">here</a></span><br />
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<span style="font-family: Arial,Helvetica,sans-serif;">This idea of avalanche problems is nothing new to our CBAC users, but we're presenting it in a slightly different way. The four key elements to the avalanche problem is the avalanche character, its distribution, its likelihood, and its size. Here's an example of how we present the problem. You can always click on the little blue "information" icons for more help or info.</span><br />
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<span style="font-family: Arial,Helvetica,sans-serif;">The trickiest part of this is the distribution rose: where the problem is located across our terrain. Imagine a conical shaped peak, and you are hovering above it in your private helicopter. The inner-most rung is the highest elevation: above treeline, and the outer-most rung is the base of the cone below treeline. Each triangular octet represents a compass direction, so imagine this conical peak is oriented the same way it would look on a map. <b>Now here's the important part.</b> We shade the areas where the problem is <b><i>most likely</i></b>. The problem distribution is never as black and white as it appears on this rose. This gives you general guidance on where you are most likely to encounter the problem at the regional level, but it is still up to you to make assessments on individual slopes. Here's an example: We get a mild snow event with strong westerly winds. Our advisory will probably shade the distribution of fresh wind slabs on leeward aspects (NE, E, SE) near and above treeline because windslabs will be fairly widespread on those slopes. Given such an event, I can almost always find wind slabs on windward aspects (due West) too, if I seek out cross-loaded features or gullies. There might be a few slopes below treeline that develop wind slabs as well. So just because the wind slabs are prevalent on higher elevation, leeward aspects, it doesn't mean you shut off your snow senses if you're traveling elsewhere. We will try to describe these nuances and subtleties in our text, so its in your best interest to read the whole advisory and not just look at the pretty pictures. </span><br />
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<span style="font-family: Arial,Helvetica,sans-serif;"><span style="font-size: small;">The likelihood is fairly self explanatory. This is the chance of triggering a slide if you are recreating in steep, avalanche terrain in the parts of the rose that we have shaded, where the problem is most prevalent. Lastly, we describe the expected size. Small avalanches are D1's: relatively harmless to people<span style="display: inline ! important; float: none; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 18px; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"> unless they push you into a terrain trap.</span> <span style="display: inline ! important; float: none; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 18px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Large avalanches are D2's: they could bury, injure or kill a person. Very large avalanches are D3's: </span></span></span><span style="display: inline ! important; float: none; font-family: ProximaNovaRegular,sans-serif; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 18px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span style="font-family: Georgia,"Times New Roman",serif;"><span style="font-family: Arial,Helvetica,sans-serif;"><span style="font-size: small;">these could bury cars, destroy a house, or break trees. Historic avalanches are nearing the maximum size a slope can produce. These don't happen every year. </span></span></span></span><br />
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<span style="display: inline ! important; float: none; font-family: ProximaNovaRegular,sans-serif; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 18px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span style="font-family: Georgia,"Times New Roman",serif;"><span style="font-family: Arial,Helvetica,sans-serif;"><span style="font-size: small;">We'd like to acknowledge Brandon Clifford, our website designer, and the CAIC for contributing resources and forecasting elements. </span></span></span></span><span style="font-family: Arial, Helvetica, sans-serif;">We hope you find our new website useful in planning and making safe decisions in the backcountry.</span>CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com2tag:blogger.com,1999:blog-8883469142001287456.post-2872301750324003582014-09-18T19:42:00.001-07:002014-09-24T17:27:29.353-07:00Get ready for winter!!<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-iBa9D_KQmzM/VBt8Hc2FRjI/AAAAAAAAAeQ/4lWfSsgOk3w/s1600/ski.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-iBa9D_KQmzM/VBt8Hc2FRjI/AAAAAAAAAeQ/4lWfSsgOk3w/s1600/ski.JPG" height="239" width="320" /></a></div>
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The gold leaves and some snow in next week's forecast are both good reminders that winter is just around the corner! Before the flakes start piling up, fall is a great time to freshen up on your avalanche education, or set aside some money and time to take an avalanche course. I've put together a list of a few educational opportunities below.<br />
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<span style="font-size: x-large;">Avalanche Training/Lectures</span></h2>
<b>WMRT Avalanche Seminar. 7 pm, November 20th, 2014. Western State Colorado University </b><br />
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<b>CBAC Avalanche Awareness Night. December 6th, 2014. CB Center for the Arts</b><br />
A night of avalanche talks, beer drinking, silent auction, raffle, and winter stoke, all to support your local avalanche center<br />
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<b>CBAC Beacon Brushup. December 7th, 2014. CB Town Park.</b><br />
Learn how to conduct an avalanche search or tune-up your beacon skills<b>.</b><br />
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<b><span style="font-weight: normal;"><b>AIARE Avalanche Courses</b> </span></b><br />
<span style="font-weight: normal;">Level 1, Level 2, and refresher courses offered locally through <a href="http://crestedbutteguides.com/2013-2014-avalanche-courses/" target="_blank">Crested Butte Mountain Guides</a> or check <a href="http://aiare.info/course_list.php" target="_blank">AIARE's schedule</a> for courses around the country. </span><b><span style="font-weight: normal;"> </span></b><br />
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<b><span style="font-weight: normal;"><b><a href="https://www.eventbrite.com/e/13th-annual-colorado-snow-and-avalanche-workshop-tickets-12913012167" target="_blank">Colorado Snow and Avalanche Workshop</a>. October 17th, 2014. Breckenridge, CO</b></span></b><br />
<span style="font-weight: normal;">A one-day seminar aimed at avalanche professionals, but with plenty of material for motivated recreationists.</span><b><span style="font-weight: normal;"> </span></b><br />
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<span style="font-size: x-large;">Weather Forecasting Courses</span></h2>
Sick of your local weather experts blowing the forecast?<b> </b><br />
<b><a href="https://www.eventbrite.com/e/mountain-weather-workshop-tickets-12708883613" target="_blank">Mountain Weather Workshop</a>. October 31st - November 2nd, 2014. Silverton, CO</b><br />
<b><a href="http://www.mountainweather.com/?page=weather_courses_and_training" target="_blank">Winter Weather Forecasting</a>. October 10th-12th, 2014. Jackson, WY</b><br />
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<span style="font-size: x-large;">Recommended Readings</span></h2>
I put together a list of some of the classic avalanche literature out there. I've ordered this list from easiest to digest to most technical reading. Grab a book for the next rainy or snowy day!<br />
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<b>Snow Sense: A Guide to Evaluating Snow Avalanche Hazard - 5th Edition. By Doug Fesler and Jill Fredston. </b><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-0HjFQoWgeW8/VBuDxyywz-I/AAAAAAAAAes/9JrMsuHLmyA/s1600/snowsense.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://2.bp.blogspot.com/-0HjFQoWgeW8/VBuDxyywz-I/AAAAAAAAAes/9JrMsuHLmyA/s1600/snowsense.jpg" height="320" width="221" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A great book for starters or if you need a refresher</td></tr>
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<b> Staying Alive in Avalanche Terrain - 2nd Edition. By Bruce Tremper</b><br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-JlI7pS7TTIY/VBuFKIgdriI/AAAAAAAAAe4/2DZLPkZWREU/s1600/staying%2Balive.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-JlI7pS7TTIY/VBuFKIgdriI/AAAAAAAAAe4/2DZLPkZWREU/s1600/staying%2Balive.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">My favorite. Bruce does a great job of describing challenging concepts using analogies and examples</td><td class="tr-caption" style="text-align: center;"><br /></td></tr>
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<b>The Avalanche Handbook - 3rd Edition. By David McClung and Pete Schaerer</b><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-Nwrx7SEABYk/VBuG26vP3EI/AAAAAAAAAfE/ihNwyvaLn7Q/s1600/avy%2Bhandbook.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-Nwrx7SEABYk/VBuG26vP3EI/AAAAAAAAAfE/ihNwyvaLn7Q/s1600/avy%2Bhandbook.jpg" height="320" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">If you want to dive into the science behind basic concepts, this is a good one.</td></tr>
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<b>Snow, Weather, and Avalanches: Observation Guidelines - 2nd Edition.</b> <br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Ue7vak0zdx0/VBuH45UEGiI/AAAAAAAAAfQ/k4mQS04HlVQ/s1600/swag.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-Ue7vak0zdx0/VBuH45UEGiI/AAAAAAAAAfQ/k4mQS04HlVQ/s1600/swag.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Learn how to make observations at a professional standard</td></tr>
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<b>International Snow Science Workshop Proceedings</b>. Free online <a href="http://arc.lib.montana.edu/snow-science/" target="_blank">here</a>.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-U-WmG2JYhBw/VBuJBNBs9cI/AAAAAAAAAfc/XYSC5AQBGmM/s1600/issw.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-U-WmG2JYhBw/VBuJBNBs9cI/AAAAAAAAAfc/XYSC5AQBGmM/s1600/issw.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Science nerds rejoice! All of the proceedings from this bi-annual conference are now online. Heavy on science.</td><td class="tr-caption" style="text-align: center;"><br /></td><td class="tr-caption" style="text-align: center;"><br /></td><td class="tr-caption" style="text-align: center;"><br /></td></tr>
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Have a great fall!<br />
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Zach Guy<br />
Forecaster, CBACCB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-86628636799008478002014-03-31T16:48:00.004-07:002014-03-31T18:32:46.434-07:00Oh no! Dust on snowYesterday, we got a brief and silty taste of the Dirty Thirties when a major dust storm blew over Crested Butte. Scarp Ridge recorded wind speeds of 110 mph (the highest of the season), and these winds brought with them a sizeable chunk of Moab.<br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-JV5QeFYAUns/UznvqQGAZJI/AAAAAAAAAcs/kTPsOiUZ-lw/s1600/1451425_10201969836183173_1829631873_n.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-JV5QeFYAUns/UznvqQGAZJI/AAAAAAAAAcs/kTPsOiUZ-lw/s1600/1451425_10201969836183173_1829631873_n.jpg" height="387" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dust-ageddon in Crested Butte on March 30, 2014. Photo credit: Matt Hogan</td></tr>
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How will this dust on snow event affect snow stability and avalanches? Lets start with a key concept: albedo. Albedo is how reflective a surface is. White colors have a high albedo -- they reflect a high amount of radiation energy rather than absorb it. That is why you reach for a light colored T-shirt if you're going outside on a hot sunny day instead of a black T-shirt. Fresh snow has a very high albedo and it reflects most incoming solar energy. (So thats why my mom always made me double up on sunscreen when I went skiing!) On the other hand, the dark-colored dust more readily absorbs solar energy and heat, and also retains that heat longer. <br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-WebK53luwI4/Uznx1Qb2NII/AAAAAAAAAc4/KVTEx-nTKSg/s1600/Fullscreen+capture+3312014+34909+PM.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-WebK53luwI4/Uznx1Qb2NII/AAAAAAAAAc4/KVTEx-nTKSg/s1600/Fullscreen+capture+3312014+34909+PM.jpg" height="340" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pristine snow reflects radiation more effectively than dusty snow. Courtesy of Jeff Deems.</td></tr>
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Dusty snow can absorb two or three times the solar energy of a clean snowpack. Whenever dust is near the surface of the snow (even when its buried up to a foot deep), it amplifies the rate of surface warming, increasing the amount of snowmelt and weakening the snow around it. This leads to more frequent <a href="http://avalanche.state.co.us/forecasts/help/avalanche-problems/loose-wet/" target="_blank">loose wet avalanches</a>. Intense melt rates send freewater deeper into the snowpack, which can also compromise the strength of deeply buried weak layers, causing an increased likelihood of <a href="http://avalanche.state.co.us/forecasts/help/avalanche-problems/wet-slab/" target="_blank">wet slab avalanches</a>. Both of these problems, with or without dust, can be avoided by monitoring how well the snowpack refreezes at night and getting off of slopes before they thaw too much. Dust on the snow simply shortens that window of stable snow and may prevent good overnight refreezes in some situations.<br />
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-w5FvXPXSLyw/Uzn6lHGot0I/AAAAAAAAAdc/Xl94wyglg2A/s1600/DSCF4338.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-w5FvXPXSLyw/Uzn6lHGot0I/AAAAAAAAAdc/Xl94wyglg2A/s1600/DSCF4338.JPG" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Snirt. Snow+Dirt. Photo taken March 31, 2014 near Crested Butte.</td></tr>
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The second avalanche concern is that dust can do weird things when its buried by a slab of snow, and it can behave like a persistent weak layer. Because they absorb and retain heat longer, dust layers can cause wet grains above or below them to remain unfrozen and unstable longer. Dust can also cause tremendous temperature gradients in the surrounding layers, which causes the bordering snow around it to decay and facet. This is not always the case, but it is worth checking on how reactive dust layers are after they get buried by spring storms. It will be the easiest layer you will ever identify in a snowpit! <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-kG3_zSgA0fM/Uzn52RJ0eZI/AAAAAAAAAdU/GKzFRyCE3S8/s1600/DSCF3238.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://2.bp.blogspot.com/-kG3_zSgA0fM/Uzn52RJ0eZI/AAAAAAAAAdU/GKzFRyCE3S8/s1600/DSCF3238.JPG" height="640" width="636" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The crown of a large slab avalanche that was remotely triggered from hundreds of yards away last spring. It failed on a dust layer.</td></tr>
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Sadly, dust on snow has negative impacts on the timing of spring runoff and water resources in the West. <a href="http://www.snowstudies.org/" target="_blank">The Center for Snow and Avalanche Studies</a> in Silverton, CO tracks and studies the effects of dust-on-snow events, and is a great resource for more information on this topic. On the bright side of things, your favorite mountain bike trails will melt out sooner now, and business is booming if you own a car-wash business. <br />
<br />
Zach Guy<br />
CBAC Forecaster<br />
<br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-63342279405498178892014-03-19T20:20:00.001-07:002014-03-19T20:20:34.105-07:00A Canary in the Elk Mountains?<div class="separator" style="clear: both; text-align: center;">
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<br />
<div class="MsoNormal">
Canaries were once used in coal mining as an early warning
system for toxic gases leaking into the mine.<span style="mso-spacerun: yes;">
</span>Signs of distress, or worse, a dead bird, would caution the miners that
it was time to retreat from the mine.</div>
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<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-SFgAucq0Ssk/UyUo2AgC_xI/AAAAAAAAAbU/llQDWYRcBno/s1600/canary.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-SFgAucq0Ssk/UyUo2AgC_xI/AAAAAAAAAbU/llQDWYRcBno/s1600/canary.jpg" height="298" width="400" /></a></div>
<div class="MsoNormal">
Last
week, a warm airmass brought our first real taste of spring to the Elk
Mountains. <span style="mso-spacerun: yes;"> </span>Nothing out of the ordinary
as far as Crested Butte weather goes, but enough that pale white skin made
its spring debut on Elk Street before hastily retreating to aloe vera
treatments. <span style="mso-spacerun: yes;"> </span>On Sunday and Monday (March 9 and 10),
temperatures rose to just above freezing at 12,000 feet under an intense March
sun.<span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span>Days later, following a few inches of snow and
cooler temperatures, we observed the results of some very unnerving deep slab
avalanches.<span style="mso-spacerun: yes;"> </span>Sometime after Monday evening,
a huge slab tore off of the south face of Mt. Owen.<span style="mso-spacerun: yes;"> </span>This appeared to be triggered by a cornice
falling onto a shallow part of the slope, but it propagated to parts of the
slab that were 12 feet deep. <span style="mso-spacerun: yes;"> </span> </div>
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<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-8c3nSwqx_y8/UyUpJ1HD2mI/AAAAAAAAAbc/4bym6Kp4-fg/s1600/DSCF4124-001.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-8c3nSwqx_y8/UyUpJ1HD2mI/AAAAAAAAAbc/4bym6Kp4-fg/s1600/DSCF4124-001.JPG" height="419" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Deep slab on Mt. Owen, first spotted 3/12/14<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="http://2.bp.blogspot.com/-HmmqM7pNDlA/UyYok4BX11I/AAAAAAAAAb8/xWUYvQZYZkw/s1600/DSCF4186.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-HmmqM7pNDlA/UyYok4BX11I/AAAAAAAAAb8/xWUYvQZYZkw/s1600/DSCF4186.jpg" height="480" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;">Looking down the crown</td></tr>
</tbody></table>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<br />
On
Wednesday night, another monster ripped off of a southwest facing ridge near
Avery Peak.<span style="mso-spacerun: yes;"> </span>This one raised the hairs on
the back of my neck.<span style="mso-spacerun: yes;"> </span>Two deep slabs back to back,
under relatively mild and stagnant weather.<span style="mso-spacerun: yes;"> </span>The Avery slide did not appear to be
cornice-fall triggered, and has raised a lot of questions and spurred a lot of
speculation on the failure mechanics among local and statewide avalanche professionals.<span style="mso-spacerun: yes;"> </span>Although meltwater on high elevation terrain
has been pretty minimal to this point, it seems plausible that a hot spot on
the slope, such as a sunbaked rock or simply an oven-like part of the slope, could have channeled heat and meltwater
into a shallow part of the snowpack.<span style="mso-spacerun: yes;">
</span>Once meltwater percolates to a buried weak layer, it can compromise the
layer’s strength causing a wide and destructive failure.<span style="mso-spacerun: yes;"> The timing of these events can be unpredictable. Maybe warming had subtle effects on the slab properties that added up just enough on this slope. We're still not sure.</span></div>
<div class="MsoNormal">
<span style="mso-spacerun: yes;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-PJxAUKC_Dss/UyUppNDUfmI/AAAAAAAAAbk/NaGCLqvBv-w/s1600/P3131369.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-PJxAUKC_Dss/UyUppNDUfmI/AAAAAAAAAbk/NaGCLqvBv-w/s1600/P3131369.jpeg" height="478" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">And another. This one near Avery Peak.</td></tr>
</tbody></table>
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<div class="MsoNormal">
<br /></div>
<span style="mso-tab-count: 1;"> </span>With
just a tease of spring under our belt and much more warm and sunny weather inevitably to
come, this begs the question:<span style="mso-spacerun: yes;"> </span>Are we
seeing the tip of the iceberg right now?<span style="mso-spacerun: yes;">
</span>Did the canary just faceplant into the bottom of the cage?<span style="mso-spacerun: yes;"> Warming and m</span>eltwater will continue progressing into the
snowpack, first on southerly slopes, and eventually around the compass to
north.<span style="mso-spacerun: yes;"> </span>We know weak layers are at the
bottom of the snowpack lurking and they are proving to be reactive.<span style="mso-spacerun: yes;"> </span>Cornice
falls will become more frequent as these overhanging blocks of snow continue to thaw and sag from their own
massive amounts of weight.<span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span>We are not out of the woods yet when it comes
to deep slab problems.<span style="mso-spacerun: yes;"> </span>These last two
slides should serve as a healthy reminder to use an extra dose of caution this spring in your backcountry travels. Be diligent in your terrain selection and in the attention you give to
weather, snowpack, and avalanche patterns in the upcoming months.<br />
<br />
Zach Guy <br />
CBAC Forecaster CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com2tag:blogger.com,1999:blog-8883469142001287456.post-74232712379059858692014-02-21T12:42:00.004-08:002014-02-21T13:09:29.627-08:00Recapping a historic avalanche cycle<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="MsoNormal">
Zach Guy<br />
CBAC Forecaster<br />
<br />
The first two weeks of February were exciting (but
sleepless) times to be an avalanche forecaster.
An unusually large storm was accompanied by unusual avalanches. Around the central and northern mountains of Colorado,
avalanches destroyed or buried buildings, closed roads, and extended trim lines
of previous historic paths. Sadly, four
fatalities occurred as well. </div>
<div class="MsoNormal">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-pMYsKBm807w/UwelgS19XkI/AAAAAAAAAVo/4AbfVXoGfy4/s1600/obs_23266_7039.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-pMYsKBm807w/UwelgS19XkI/AAAAAAAAAVo/4AbfVXoGfy4/s1600/obs_23266_7039.jpg" height="480" width="640" /></a></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<br />
<div class="MsoNormal">
I put together a simplified summary of the storm and a timeline of natural avalanche activity, highlighting some of the largest
and/or most unusual avalanches that occurred around our Crested Butte
backcountry and surrounding roads. I’m certain this is only a
small percentage of the natural avalanches; our zone is too vast to get the
full picture from our lookout points and observations. I ordered and dated these avalanches
according to the first date that they were observed or reported to us, but the exact failure dates are
open for speculation.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The storm began January 30<sup>th</sup>, with a quick and
massive hit of roughly 4.0” of SWE in the favored zones and 2.0” of SWE near
town in just 60 hours. Natural
avalanches were widespread, but confined to the new snow, and most common at
low elevations where the surface snow was weakest.
We were a bit surprised not to see any deeper slides in the alpine when
the clouds cleared for a day on February 2<sup>nd</sup>. Maybe our snowpack was tougher than we thought??</div>
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-E6TynOIMWZM/UwekMGAaSyI/AAAAAAAAAVU/LqXqk5XfWAY/s1600/20140202_Anthracites.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-E6TynOIMWZM/UwekMGAaSyI/AAAAAAAAAVU/LqXqk5XfWAY/s1600/20140202_Anthracites.JPG" height="305" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Anthracite Range. Observed February 2nd. </td></tr>
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Snowfall picked up again on February 3<sup>rd</sup>: fluffy
snow, modest accumulations, with moderate winds, and a lull in avalanche
activity. On the night of February 7<sup>th</sup>,
the Pacific river of moisture found a direct path to Crested Butte. Wind assisted snow transport had been steady and relentless
for several days, and Gothic was the first to shed in a big way. The NE face ran full track, crossed the East River, and ran uphill burying (and perhaps destroying?) a newly installed outhouse structure in the Judd Falls parking area. Oh crap! Several observers called this one a D4, about as big as they get in Colorado. </div>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-MKjfqtnBfqU/Uwem57ZT3JI/AAAAAAAAAV0/LeOuyMO96MM/s1600/20140208_Gothic.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-MKjfqtnBfqU/Uwem57ZT3JI/AAAAAAAAAV0/LeOuyMO96MM/s1600/20140208_Gothic.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Gothic Mountain runout. The pipe is to the top of the outhouse structure that was buried 10-20 feet deep. Observed February 8th. </td></tr>
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The river of moisture was relentless until February 10<sup>th</sup>,
and the favored mountains picked up another whopping 3.5” of SWE while Mt. CB got 2.5”
over the 4-day period. Schofield Pass hit 9.5" of SWE over the storm period. Winds continued at moderate speeds, with the usual stronger gusts. We had no
visibility and limited avalanche observations during this time. Then the clouds lifted on February 10th and 11th, and revealed a warzone. Almost everything steep near town had slid, from small road cuts, to river banks, to more sizeable paths. Almost all of Snodgrass had slid, breaking trees and covering Gothic Road in feet upon feet of debris. Debris ran across Peanut Lake Road and onto the nordic tracks. Unusual crowns were all over the mountains closer to CB South. Deep slabs pulled out of the Ruby Range. Slides that hadn't run in 20 years crossed Cement Creek Road. At least 5 paths crossed Taylor Canyon Road, and several structures near Almont and in Taylor Canyon were impacted. At least 4 paths crossed Spring Creek Road (not sure on the timing of these last few slides...could have been a few days later).</div>
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Ur5YUNqPyaM/UweqdPfcmvI/AAAAAAAAAXE/-449_D2QtzI/s1600/obs_23012_6801-r.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-Ur5YUNqPyaM/UweqdPfcmvI/AAAAAAAAAXE/-449_D2QtzI/s1600/obs_23012_6801-r.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This slide crossed Peanut Lake Road around 8:30 a.m. February 10th. </td></tr>
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<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-ThU21wYmhTs/UwerDD_Bj6I/AAAAAAAAAXU/dyUutLcg9jE/s1600/image4.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://2.bp.blogspot.com/-ThU21wYmhTs/UwerDD_Bj6I/AAAAAAAAAXU/dyUutLcg9jE/s1600/image4.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An estimated 2/3 of Snodgrass Mountain slid to near the ground. Observed February 10th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-nax2YQh5jy8/UwesLscqzlI/AAAAAAAAAX8/XQs0zbHs9O4/s1600/obs_22970_6767-r.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-nax2YQh5jy8/UwesLscqzlI/AAAAAAAAAX8/XQs0zbHs9O4/s1600/obs_22970_6767-r.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Unusual crowns on Double Top Mountain. Observed February 10th</td></tr>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-Ebc9-p1ylUM/Uwex044i8nI/AAAAAAAAAZk/XIZjdm7Leao/s1600/obs_22970_6776-r.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-Ebc9-p1ylUM/Uwex044i8nI/AAAAAAAAAZk/XIZjdm7Leao/s1600/obs_22970_6776-r.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Large slides above town from Gibson Ridge. Observed February 10th.</td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Crown lines running across the entire width of Cement Mountain. Observed February 10th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-oJAFLhbpEAQ/UwesRo7EfNI/AAAAAAAAAY4/GEFxl5eOfJw/s1600/obs_23012_6802.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-oJAFLhbpEAQ/UwesRo7EfNI/AAAAAAAAAY4/GEFxl5eOfJw/s1600/obs_23012_6802.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Slides near Meridian Lake. Observed February 11th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-HdCE7sj58e4/Uwepn8-EY-I/AAAAAAAAAWs/J6LAFJQWduw/s1600/3432575720image.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://2.bp.blogspot.com/-HdCE7sj58e4/Uwepn8-EY-I/AAAAAAAAAWs/J6LAFJQWduw/s1600/3432575720image.JPG" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Peeler Basin. Estimated half mile wide. Observed Februay 11th. </td></tr>
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-W7dZ3eX1zfA/Uwepnw-xhkI/AAAAAAAAAWw/VMrB4xGFAHg/s1600/3432575722image.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-W7dZ3eX1zfA/Uwepnw-xhkI/AAAAAAAAAWw/VMrB4xGFAHg/s1600/3432575722image.JPG" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Deep slab on Purple Mountain, estimated up to 20+ ft deep. Observed February 11th. </td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Deep slab on Afley. Observed February 11th.</td></tr>
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Small doses of snow fell and wind speeds increased on February 12th through the 15th. Temperatures started to climb, eventually hitting the high 40's in Crested Butte. We even saw short bouts of rain at all elevations. The natural cycle was far from over. Another natural came down to Cement Creek Road. A few more huge ones ripped off of the peaks. </div>
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-98PQ6-W2fjc/Uwezt7Mu7lI/AAAAAAAAAaM/mZR9e4vscUo/s1600/20140217_White.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-98PQ6-W2fjc/Uwezt7Mu7lI/AAAAAAAAAaM/mZR9e4vscUo/s1600/20140217_White.JPG" height="335" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Near White Mountain; this path ran similar to the notorious skier triggered slide from 2008. Observed February 14th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-p61qaZfNj48/Uwe3ooA_5oI/AAAAAAAAAao/GGYfXcZLqxg/s1600/photo.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-p61qaZfNj48/Uwe3ooA_5oI/AAAAAAAAAao/GGYfXcZLqxg/s1600/photo.jpeg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Several historic slides crossed Spring Creek Road. Observed February 14th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-305L0ePwWss/Uwexi8TJA2I/AAAAAAAAAZM/QKofHVkNzHU/s1600/2014-02-16+12.15.31.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-305L0ePwWss/Uwexi8TJA2I/AAAAAAAAAZM/QKofHVkNzHU/s1600/2014-02-16+12.15.31.jpg" height="400" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Slides across Cement Creek. Observed February 14th and 15th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-z4avo3K6-40/Uwe1LJmeCvI/AAAAAAAAAaY/RqZRZxaH2tE/s1600/obs_23134_6929-r.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-z4avo3K6-40/Uwe1LJmeCvI/AAAAAAAAAaY/RqZRZxaH2tE/s1600/obs_23134_6929-r.jpg" height="298" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Slides impacted structures in Taylor Canyon and near Almont. Observed February 15th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-_WTbpXT3weo/UwexrzLPjCI/AAAAAAAAAZU/lcmFDMB1LYA/s1600/Feb+14+avalanche+cycle-1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-_WTbpXT3weo/UwexrzLPjCI/AAAAAAAAAZU/lcmFDMB1LYA/s1600/Feb+14+avalanche+cycle-1.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Slab failing near the ground on Whetstone. Observed February 16th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-s9u7TYwYHMo/Uwexvsp5CBI/AAAAAAAAAZc/S5UEF-rlTyQ/s1600/Feb+14+avalanche+cycle-2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-s9u7TYwYHMo/Uwexvsp5CBI/AAAAAAAAAZc/S5UEF-rlTyQ/s1600/Feb+14+avalanche+cycle-2.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Another D4 off of Peeler Mountain. Observed February 17th.</td></tr>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-0mW0wktYcSA/Uwex5zcg01I/AAAAAAAAAZs/5Qig094F8o0/s1600/obs_23266_7041-r.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-0mW0wktYcSA/Uwex5zcg01I/AAAAAAAAAZs/5Qig094F8o0/s1600/obs_23266_7041-r.jpg" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Near WSC Peak. Observed February 17th</td></tr>
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This memorable cycle was spooky, challenging, exciting, and stressful all at once. I wish I had a helicopter to fly around the range now to get a full view of the impacts of this cycle. </div>
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Thank you to everyone for submitting observations the past few weeks. A special thanks to Ben Pritchett, Ian Havlick, Pete Sowar, Briant Wiles, Andrew Breibart, Jayson Simons-Jones, and Gary Dotzler for their photos. </div>
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-1983084010640204812014-02-13T13:07:00.002-08:002014-02-13T15:06:55.902-08:00Digging out the details of this storm. How big was it?<div class="separator" style="clear: both; text-align: left;">
Zach Guy</div>
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CBAC Forecaster</div>
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<tr><td class="tr-caption" style="text-align: center;">Natural deep slab off of Afley Peak</td></tr>
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<span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">Since January 29</span><span style="font-family: Calibri; font-size: 9px; vertical-align: super;">th</span><span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">, the mountains around Crested Butte have been walloped by heavy snowfall. On February 10</span><span style="font-family: Calibri; font-size: 9px; vertical-align: super;">th</span><span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">, the storm finally cleared. My back is nearly broken from endless shoveling, my roof has avalanched at least twice, and I’ve heard lots of folks saying this is the biggest storm they’ve ever seen. How historic was this storm?</span></div>
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<span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">The Schofield Pass SNOTEL site is a remote weather station north of Gothic Townsite that measures snow depth and snow water equivalent at hourly intervals. Snow water equivalent (SWE) is the amount of water that would melt out of the snow falling from the sky. An inch of rain measures as an inch of SWE, and a foot of snow typically produces about an inch of SWE. Between January 29</span><span style="font-family: Calibri; font-size: 9px; vertical-align: super;">th</span><span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;"> and February 10</span><span style="font-family: Calibri; font-size: 9px; vertical-align: super;">th</span><span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">, Schofield Pass received 9.5” of SWE. That's easily 10 feet of snow! Since Schofield’s weather station was installed in 1985, four major storms stand out, with a return interval of roughly 6 years: February 1986 (13.5” SWE), February 1995 (9.7” SWE), January 2005 (8.0” SWE), and December 2010 (9.4” SWE). All of these storms came in unusually warm, with abundant moisture streaming from the Pacific. Three out of four of these storms resulted in Extreme avalanche danger, with widespread and long-running avalanches into valley bottoms. </span></div>
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<a href="http://4.bp.blogspot.com/-NpAslM1NTPc/Uv0zE49ZwiI/AAAAAAAAAUc/-Cr86SLWwNQ/s1600/Schofield+Snotel+Storm+Comarison+Chart.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-NpAslM1NTPc/Uv0zE49ZwiI/AAAAAAAAAUc/-Cr86SLWwNQ/s1600/Schofield+Snotel+Storm+Comarison+Chart.jpg" height="296" width="400" /></a></div>
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<span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">This storm, with 9.5” SWE, is comparable in precipitation levels to these previous historic storms, but it fell over nearly twice the time span. At the avalanche center, we compared our current storm to previous storm patterns to help decide whether to upgrade the danger to extreme. Extreme danger means very large and destructive avalanches are widespread; the type of danger where we might expect Red Lady Bowl to come across Kebler Pass Road. It’s a very challenging forecast when the mountains are socked in clouds and we have very few observations to work off of. During this storm, we rated the avalanche danger as high during 5 days of the storm. After the clouds cleared, we observed widespread avalanches and a dozen or more very destructive avalanches. One ran off of Gothic Mountain, crossed the East River, and buried a structure 20 feet deep! Did we hit extreme danger? I'm not sure..we were dang close. There are two reasons we didn't bump the danger to extreme on February 10th: The storm reached its maximum precipitation rate early in the storm rather than late, and it happened over a span of 13 days, while the other historic storms came in over 6 or 7 day periods. All in all, it was a memorable storm and ranks as one of the larger storms we’ve seen in the past 30 years. Whether it was at the ski resort, in the backcountry, or driving your car to work, I hope you found some of that fluffy white stuff flying in your face!</span></div>
<span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;">Thanks to Art Mears and Ben Pritchett for their contributions to this article.</span><br />
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<tr><td class="tr-caption" style="text-align: center;">Large natural avalanches off of Snodgrass Mountain snapped trees and crossed Gothic Road</td></tr>
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<span style="font-family: Calibri; font-size: 15px; vertical-align: baseline;"><br /></span>CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-52243989110381013532013-12-18T11:47:00.001-08:002013-12-18T14:32:09.829-08:00What is surface hoar?<div class="MsoNormal">
You may have heard us warning backcountry skiers and riders
about buried surface hoar in our avalanche advisories this month. So what is this lurking predator and how do
we know where to find it? </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-5rGI2esgyTo/UrH7ghDPp4I/AAAAAAAAAR4/nJvBOIe_jiw/s1600/p1010098.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="213" src="http://3.bp.blogspot.com/-5rGI2esgyTo/UrH7ghDPp4I/AAAAAAAAAR4/nJvBOIe_jiw/s320/p1010098.jpg" width="320" /></a></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Surface
hoar, sometimes called “hoar frost”, is that beautiful, glimmering, feathery
crystal you’ve probably admired while strolling around town. When it gets buried on a steep slope, it can
be an incredibly fragile and dangerous weak layer that can persist for weeks or
months. Surface hoar is the winter
version of dew. In order for it to form,
we need 3 ingredients: clear nighttime
skies without canopy cover, calm winds, and some relative humidity in the air. Of course, these feathery crystals aren’t a
problem unless they are preserved below a slab of snow. In Crested Butte, we frequently see strong
winds prior to the arrival of the next storm, which helps destroy those fragile
layers. Sun-baked slopes can also cook
the layer into submission. The take-home
point here is that there are a lot of factors at play that can make for
variable and spotty distribution of buried surface hoar; some slopes may have
it while others don’t.</div>
<br />
<div class="MsoNormal">
We had
a significant surface hoar event around Thanksgiving that was buried on some
slopes after our early December storms. We’ve
been finding it preserved on shaded and wind protected or leeward slopes,
especially at lower elevations. It has
been the culprit for a handful of avalanches these past few weeks. This layer has been fairly easy to identify
in a snow pit: it looks like a thin grey stripe in the snow (this is not always
the case). <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-d8xduzOnSow/UrIiD1Ucd7I/AAAAAAAAASc/ABEZBFH50Cg/s1600/IMG_4136.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://3.bp.blogspot.com/-d8xduzOnSow/UrIiD1Ucd7I/AAAAAAAAASc/ABEZBFH50Cg/s400/IMG_4136.jpg" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The obvious grey stripe in the middle of the pit is a layer of buried surface hoar found on Schuykill Ridge this week.</td></tr>
</tbody></table>
We are just exiting another
high pressure weather pattern that is favorable for surface hoar growth. When you’re out touring in avalanche terrain,
look for surface hoar and what slopes it is forming on to give you a better
idea of places to avoid if it gets buried and becomes problematic. And don’t forget check our website for the
most up-to-date avalanche conditions before you head out. <a href="http://www.cbavalanchecenter.org/">www.cbavalanchecenter.org</a><br />
<br />
-Zach Guy</div>
CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-88452134333850180852013-12-09T19:03:00.002-08:002013-12-17T19:32:57.624-08:00Grizzly Gulch Near MissSuper well documented near miss today in the backcountry near Alta, UT. Check it out and learn from other's mistakes..<br />
<br />
<a href="http://utahavalanchecenter.org/avalanches/18960">http://utahavalanchecenter.org/avalanches/18960</a><br />
<br />
<br />
Skier's account from her own blog below:<br />
<br />
<a href="http://amieski.com/2013/12/12/blind-spot/">http://amieski.com/2013/12/12/blind-spot/</a><br />
<br />
Photographer's own account<br />
<br />
<a href="http://blackdiamondequipment.com/en/experience-story?format=landing&cid=adam_clark_grizzly_gulch">http://blackdiamondequipment.com/en/experience-story?format=landing&cid=adam_clark_grizzly_gulch</a><br />
<br />
-IanCB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-22162404773893639062013-12-08T08:27:00.002-08:002013-12-08T14:45:43.920-08:00No Niño?? For the past several years, much of the early season buzz about whether we were going to have a killer winter or a dud revolved (over. and over. and over...) about the pros and cons of an El Niño or La Niña atmospheric and oceanic signal. <br />
<br />
Here is a post from one of my former meteorology professors at the University of Utah and total powder junkie himself, Jim Steenburgh.<span style="background-color: white; color: blue; font-family: Arial, Tahoma, Helvetica, FreeSans, sans-serif; font-size: 12px; line-height: 16px; text-decoration: none;"> </span>He runs a great weather blog that discusses meteorology mostly around Utah, but a ton of his material is applicable to our locale as well. Bookmark it and check it out! Infer what you can about how the lack of ENSO will affect our weather patterns...the overarching theme being....your guess is as good as mine. A good perspective if nothing else. <br />
<br />
<a href="http://wasatchweatherweenies.blogspot.com/2013/08/outlook-for-20132014-ski-season.html">http://wasatchweatherweenies.blogspot.com/2013/08/outlook-for-20132014-ski-season.html</a><br />
<br />
My take is that the Arctic Oscillation is just as big of a contributing factor that is often over looked. "The positive phase of the Arctic Oscillation brings ocean storms farther north, making the weather wetter in Alaska, Scotland, and Scandinavia and drier in the western United States and the Mediterranean. In the negative phase of the Arctic Oscillation the patterns are reversed. A strongly negative phase of the Arctic Oscillation brings warm weather to high latitudes, and cold, stormy weather to the more temperate regions where people live. Over most of the past century, the Arctic Oscillation alternated between its positive and negative phase. For a period during the 1970s to mid-1990s, the Arctic Oscillation tended to stay in its positive phase. However, since then it has again alternated between positive and negative, with a record negative phase in the winter of 2009-2010"(National Snow and Ice Data Center).<br />
<span style="background-color: white; line-height: 24px;"><span style="font-family: Times, Times New Roman, serif;"><br /></span></span>
<br />
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<a href="http://4.bp.blogspot.com/-NFG0veWLmW8/UqScJOegqcI/AAAAAAAAARY/UZg8kWE3aEE/s1600/arctic_oscillation-sm.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-NFG0veWLmW8/UqScJOegqcI/AAAAAAAAARY/UZg8kWE3aEE/s1600/arctic_oscillation-sm.jpg" /></a></div>
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<br /></div>
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What tilt are we in now you may ask??</div>
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<br /></div>
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<a href="http://3.bp.blogspot.com/-7aOy47hBDww/UqSdUGrIaaI/AAAAAAAAARk/lE3nsc8JTmE/s1600/ao.mrf.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-7aOy47hBDww/UqSdUGrIaaI/AAAAAAAAARk/lE3nsc8JTmE/s1600/ao.mrf.gif" /></a></div>
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<br /></div>
<div class="separator" style="clear: both; text-align: left;">
These are very interesting (and confusing) but if you look at each graph, you have a neutral AO signal at zero, with the blue bars going up meaning positive, going down, negative. Makes you think a little what phase we have been in for extreme weather, like our early season snows, the Front Range floods in September, etc.</div>
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<br /></div>
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More info here:</div>
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<br /></div>
<div class="separator" style="clear: both; text-align: left;">
<a href="http://www.nc-climate.ncsu.edu/climate/patterns/NAO.html">http://www.nc-climate.ncsu.edu/climate/patterns/NAO.html</a></div>
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<br /></div>
<div class="separator" style="clear: both; text-align: left;">
<a href="http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml">http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml</a></div>
<div class="separator" style="clear: both; text-align: left;">
<br /></div>
<br />
I will probably steer some of my posts of this forecaster's blog to Jim's blog occasionally. Enjoy this snowy Sunday...so far I like No Niño...<br />
<br />
-Ian HavlickCB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-65165433348075710092013-12-07T06:51:00.001-08:002013-12-07T06:52:17.816-08:00TED Talk on Avalanche Hazard and RiskGrant Statham gave a great TED talk recently on risk in
avalanche terrain that has been circulating around the avalanche community lately. Grant has spent a lifetime climbing, skiing and
guiding in extreme terrain around the world and he has spent the past 10
years or so working as a risk management specialist for Parks Canada. Grant does a great job of explaining risk and hazard and how it relates to travel in avalanche terrain in this TED talk. <br />
<br />
See
Grant's 12 minute talk by clicking <a href="http://tedxtalks.ted.com/video/Risk-The-Anatomy-of-Chance-and;search%3Agrant%20statham">HERE</a> or on Grant's photo below.<br />
<br />
<a href="http://tedxtalks.ted.com/video/Risk-The-Anatomy-of-Chance-and;search%3Agrant%20statham"><img alt="" src="http://utahavalanchecenter.org/sites/default/files/images/staff/Bruce/Grant%20Statham%20TED%20talk.jpg" style="height: 285px; width: 400px;" /></a><br />
<em>Grant Statham from Parks Canada</em><br />
<br />
The components of avalanche risk from Bruce Tremper's (Utah Avalanche Center Director) new book Avalanche Essentials, which illustrate the points Grant makes in his talk.<br />
<img alt="" src="http://utahavalanchecenter.org/sites/default/files/images/staff/Bruce/Slide01.jpg" style="height: 300px; width: 400px;" /><br />
<br />
-Ian Havlick<br />
CBAC Forecaster<br />
<br />
<br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-75494653002585930492013-04-11T20:02:00.004-07:002013-04-11T20:03:17.401-07:00Spring Skiing and Wet Slabs<style>
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Spring is a great time to get into the backcountry and enjoy
the expansive mountain ranges surrounding town.<span style="mso-spacerun: yes;"> </span>You can safely pass through steep, avalanche terrain on most
days, but there are still a few hazards that need to be on your radar, one of
which is wet slabs.<span style="mso-spacerun: yes;"> </span></div>
<div class="MsoNormal">
Presently, our high peaks either have a dry, winter snowpack
(on north aspects), or are in some transitional stage as you move towards
southerly aspects. <span style="mso-spacerun: yes;"> </span>Many of
these slopes have weak layers at the bottom of the snowpack that formed early this
winter.<span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span>As the days get warmer and the sun angle gets higher,
meltwater at the surface begins to percolate through the dry snow. We call this
the “wetting front.”<span style="mso-spacerun: yes;"> </span>As water
moves through the snow, it changes the snow’s properties, causing it to
weaken.<span style="mso-spacerun: yes;"> </span>When it refreezes at night,
frozen ice bonds form which make for a very strong and very stable
snowpack.<span style="mso-spacerun: yes;"> </span>When the wetting front
advances to a weak layer, that layer can lose all of its strength and fail,
resulting in a huge, wet slab avalanche. These are one of the most destructive
types of avalanches we see. </div>
<div class="MsoNormal">
Every winter we have weak layers near the ground, and every
spring meltwater percolates through them.<span style="mso-spacerun: yes;">
</span>Yet in most years, we only see a handful of wet slabs.<span style="mso-spacerun: yes;"> </span>These are very hard to predict on a
slope by slope basis, but you can eliminate your risk with a few spring skiing/riding
practices.<span style="mso-spacerun: yes;"> </span></div>
<div class="MsoNormal">
(1) Wet slabs are most common after several consecutive
nights without a good refreeze.<span style="mso-spacerun: yes;">
</span>Avoid avalanche terrain if it didn’t refreeze well overnight.<span style="mso-spacerun: yes;"> </span>Clear, cold nights make for a good
refreeze; cloudy, warm nights leave a poor refreeze.<span style="mso-spacerun: yes;"> </span>Look at mountain temperature sensors (found at http://www.cbavalanchecenter.org/page.cfm?pageid=12570)
and note the cloud cover before you leave home.<span style="mso-spacerun: yes;"> </span>When you’re on slope, you can dig or probe to feel how thick
that frozen block of snow is. On your hike up, if you are breaking through to
your waist in wet grains, that’s a bad sign.<span style="mso-spacerun: yes;"> </span></div>
<div class="MsoNormal">
(2) Wet slabs are most common during rapid or unusual
warm-ups.<span style="mso-spacerun: yes;"> </span>Plan to get off of
slopes early in the day, when it is an inch of nice corn skiing rather than 8”
of sloppy slush skiing.<span style="mso-spacerun: yes;"> </span>This often
means starting your hike before sunrise.<span style="mso-spacerun: yes;">
</span>If you got a late start, go towards slopes that get sun later in the
day, such as west or north aspects, rather than east or south aspects.<span style="mso-spacerun: yes;"> </span>With your descent, anticipate that
slopes lower in elevation or more easterly in aspect warmed up quicker; you
might have to ski some frozen crust up high to play it safe down low.<span style="mso-spacerun: yes;"> </span>Don’t go skiing if it is raining
(duh).<span style="mso-spacerun: yes;"> </span>If weather forecasters are
talking about record high temperatures, go biking or drink beer on your
deck.<span style="mso-spacerun: yes;"> </span></div>
<div class="MsoNormal">
Thanks from the CBAC for another great season! We couldn’t
do it without your support and observations.<span style="mso-spacerun: yes;"> </span>Have a fun and safe spring ski season.<span style="mso-spacerun: yes;"> </span></div>
<br />
-Zach Guy<br />
*)<br />
(*<br />
*)<br />
(* CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-3270340314737109102013-02-13T06:23:00.000-08:002013-02-14T16:00:42.273-08:00When do Persistent Slabs go away?<div style="text-align: left;">
Steve Banks</div>
<div style="text-align: left;">
Executive Director</div>
<div style="text-align: left;">
CBAC<br />
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<br /></div>
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<br /></div>
<div class="MsoNormal">
You may have noticed that the Crested Butte Avalanche
Center’s daily bulletin has been talking about the persistent slab problem for
most of the winter now. We have also had some other avalanche problems such as
storm slabs, wind slabs and even wet loose avalanche problems. These problems
seem to come and go, while persistent slabs stay in the bulletin day after day.
So when will the persistent slabs go away?</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Persistent slabs is the name we give to the avalanche
problem when we have a weak layer that is made up of faceted snow grains, depth
hoar or surface hoar with a thick denser layer above. These types of weak snow
grains tend to change very slowly and often linger throughout the entire winter
season. Really it is a persistent weak layer that is the problem, but since it
is the <i>slab</i> that could potentially
kill you, we call it a persistent slab avalanche problem. These particular weak
layers need a lot of time to morph into a better type of snow grain, and often
we get into full on spring corn cycles before these layers begin to look any better.
</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So it would seem that if persistent slabs are really a
problem, we must be triggering a lot of avalanches, right? Well, not really.
These weak layers can have a certain amount of strength to them. The trick is
to be able to recognize where and when they are strong enough to support the
overlying snow as well as the additional weight of a backcountry rider. This is
why we perform snowpack test like compression test and extended column tests.
We are trying to determine how strong the weak layers may or may not be. Given
the idea that stronger layers over weaker layers in the snowpack create
avalanches, merely looking at the structure of the snowpack would indicate
dangerous conditions. However snowpack tests are beginning to show harder
results leading us to believe that the snowpack is gaining strength. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Now comes the tricky part. If the weak layers creating the
persistent slab avalanche problem are becoming stronger, how do we know where
and when they are strong enough to trust? It is always difficult to assess
where an avalanche will occur, but it is especially difficult during times of
relatively benign weather. This is when forecasters will be talking about low
likely hood and high consequences avalanches. While it is difficult to initiate
the slide, the resulting failure could entrain a lot of snow and have a life
threatening outcome. So where would you be more likely to trigger an avalanche?
The best way to know the answer is to dig in to the snow to check out the
layering and perform some tests to see just how strong the slab is and just how
weak the weak layers are. In
general we have a weaker snowpack closer to the town of CB where the snowpack
is shallower. Stronger snowpacks can be found deeper in the mountains where the
snowpack is deeper. When in doubt, err on the side of caution, and always
remember to check the current avalanche bulletin at <a href="http://www.cbavalanchecenter.org/">www.cbavalanchecenter.org</a>. </div>
CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-75887807513812443102013-02-05T16:00:00.000-08:002013-02-14T16:09:02.384-08:00Interpreting Snowpack Layers and Hardness<!--[if gte mso 9]><xml>
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<div class="MsoNormal" style="line-height: 150%;">
<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">When the word avalanche is mentioned,
images of curtains of snow cascading down the mountain come to mind. Specific
conditions create avalanches. One of the basic elements, of course, is snow.
The snowpack (the seasons snow on the ground) is a complex, but a key to
understanding it is identifying layers and differences between them. Layers
within the snowpack are a record of the winter’s weather. Like tree rings or
strata of rock, layers can be traced to dates and conditions that formed them.</span></div>
<div class="MsoNormal" style="line-height: 150%;">
<br /></div>
<div class="MsoNormal" style="line-height: 150%;">
<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";"><span style="mso-spacerun: yes;"> </span>One of the most important characteristics of a
layer is its hardness. Harder snow is stronger and cohesive, while softer snow
is weaker. For a slab avalanche we need a strong layer over a weak layer. We
actually use a “Hand Hardness” scale by pushing our hand into each layer to
determine the hardness. “Fist” hard snow is the softest, then “four finger”,
then “one finger” snow being harder, and so on. No, there’s no “middle finger”
on this scale. The greater the hardness difference of neighboring layers, the
more likely we are to see avalanches at that interface.</span></div>
<div class="MsoNormal" style="line-height: 150%;">
<br /></div>
<div class="MsoNormal" style="line-height: 150%;">
<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">The recent snowpack history from the
Crested Butte backcountry is a great example of layer hardness relating to
human triggered avalanches. Consider these three scenarios:</span></div>
<div class="MsoNormal" style="line-height: 150%;">
<br /></div>
<div class="MsoNormal" style="line-height: 150%;">
<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">1) The last week in January brought up
to 50” of snow over seven days. While this storm caused some natural
avalanches, riders initially weren’t triggering many slab avalanches. Most of
the snow came in light and soft. Digging in sheltered and shaded areas during
the middle of the storm, you’d find very soft (fist hard) new snow on top of
some slightly harder old snow.</span></div>
<div class="MsoNormal" style="line-height: 150%;">
<br /></div>
<div class="MsoNormal" style="line-height: 150%;">
<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">2) The storm ended on Thursday January
31<sup>st</sup>. By then the wind had formed stiff slabs at all elevations but
especially near and above treeline. Digging on some leeward slopes near
treeline you could find one finger hard wind-loaded snow sitting over four
finger hard facets. Many reports of natural and skier triggered slides came in
from wind-loaded areas.</span></div>
<div class="MsoNormal" style="line-height: 150%;">
<br /></div>
<div class="MsoNormal" style="line-height: 150%;">
<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">3) By Monday, February 4th, the storm had ended four
days prior. Mild daytime temperatures had created settlement in the height of
the storm snow and an increase in its hardness. I was skiing on sheltered
easterly aspects below treeline.<span style="mso-spacerun: yes;"> </span>These
slopes had seen very little wind in the past week. Throughout the day, we felt
many rumbling collapses and we remotely triggered two sizable avalanches. On
these sheltered slopes we found storm snow that had stiffened to a hardness of
four finger sitting over fist hard facets.</span></div>
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<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">This storm and avalanche cycle in the late January to early February shows how layer hardness often relates to skier triggering. The most consistent skier-triggering
occurred where we found the most change in hardness in adjacent strong over weak layer. If this
talk of layers seems daunting, remember that you don’t have to figure it out on
your own. The daily avalanche forecast is best place for current conditions.
You can check out the "Observations" page to read what other backcountry travelers are seeing. You could even look at the "Snow Profiles" page for technical graphs of recent snow pits. From there you can investigate the snow as much or as little as you want. But
most of all have fun in the mountains, make sound decisions, and stay safe
doing it. Check out the daily forecast at www.cbavalanchecenter.org</span></div>
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<span style="font-family: Arial; mso-bidi-font-family: "Times New Roman";">CBAC Forecaster Josh Hirshberg </span></div>
CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-61182786198137748562013-02-04T17:28:00.004-08:002013-02-04T17:29:51.225-08:00Some Crusty Thoughts<br />
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South facing slopes were the go-to for
many folks in town to find stable skiing and riding during our
December storm cycle. The snow fell on dirt on many low elevation
sunny slopes, rather than the problematic facets that were lurking on
shaded slopes. Someone asked me recently, “When do south aspects
become dangerous?” It depends, of course, but a lot of it has to
do with crusts. With all the sun we’ve been getting in January,
we’ve seen melt-freeze crusts form on most of our southerly slopes.
So what does this mean for future stability and what happens when
snow piles on above crusts?<br />
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There are a lot of variables at play,
so I’ll illustrate with a few examples. The best case scenario is
that we have a thick, stout crust that is still warm as a new storm
arrives, and the new snow falls warm and wet. Instabilities at this
crust/new snow interface will be short-lived because a good bond will
form. This pattern is more often played out in the springtime, which
is why we can sometimes find stable powder skiing after a spring
storm drops snow on widespread crusty surfaces.
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The worst case scenario is if we have
facets form and stay preserved above a crust prior to a big snowfall.
This can happen in a number of ways. Mid-winter, we will
occasionally see crusts form on days when it is still pretty cold,
but there is strong enough solar radiation to warm and melt the snow
just below the surface. The actual surface of the snow stays cool
because it radiates heat, so what we have is a thin crust forming
below cold faceting snow at the surface. Suddenly we have a bed
surface with a weak layer waiting for a slab to ruin someone’s day.
A similar scenario is if we have a crust that has been forming for
days or weeks, and then we get a dusting of snow on top followed by
clear and cold weather. This gives us another scary bed surface with
facets developing above it. Often these facets above crusts are
difficult to spot with the naked eye after they are buried by a slab,
but a stability test will usually give them away.</div>
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Now here’s the really tricky part.
When a crust gets buried, it can have unusual behavior. Crusts act
as vapor barriers to the normal, everyday movement of water vapor
through the snowpack (Picture TSA security clogging the flow of
people at an airport). This can lead to faceting above or below the
crust, even if the bonds were originally strong. This type of
problem is most common in cold, shallow snowpacks such as what we
have in Crested Butte right now. We have already observed pronounced
facets developing under our current crusts on south aspects. With a
big enough load, that crust won’t be able to support the weight
above it and the whole thing will come crashing down, failing on
those facets below the crust.
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So if I’ve lost you with all this
technical jibber jabber, here’s the bottom line. Crusts have the
potential to be a dangerous interface as more snow piles above them.
Treat a buried crust as guilty until proven innocent. Watch for
signs of instability and dig down to check how the snow is bonding to
that crust before committing to steep terrain. And remember that
south facing slopes that you were skiing or riding safely back in
December may no longer be stable if we get another big storm cycle.
For daily avalanche advisories and observations, visit
cbavalanchecenter.org</div>
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CBAC Forecaster Zach Guy</div>
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<br />CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0tag:blogger.com,1999:blog-8883469142001287456.post-54231301793821582372013-01-15T11:02:00.001-08:002013-02-04T06:41:55.701-08:00Tech Tip: Did Your Compression Test Just POP or DROP?<br />
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Recent research in the snow and avalanche world is showing
that how a compression test fails is just as or more important than the number
of taps it takes for it to fail. Researchers have come up with a classification
system to qualify and describe fractures in snowpack tests. This system is known
as Fracture Character. Fracture Character does not necessarily replace Shear
Quality—or the “Q scale.” It compliments it, and can even provide a bit more
information about the relationship of the weak layer and the overlying slab. It
breaks fracture type into 2 main categories—sudden fractures and non sudden fractures. This post will solely deal with sudden fractures.</div>
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Sudden fractures are what avalanche practitioners call
“pops” and “drops” in snowpack tests. If the fracture is a pop, a thin crack
will cross the column of snow with one loading step (or tap) and the block will
slide off the weak layer easily. It could be your 5<sup>th</sup> tap or your 20<sup>th</sup>—the
key is that one tap initiates a crack that crosses the entire snowpack column. This
may not be as obvious as the old analogy of “it shot out like a cash register
drawer.” On lower angle slopes you may have to grab the block and give it a slight
tug. If it slides off without much effort you are still dealing with a pop. If
it is a drop there will be an observable (and sometimes audible) collapse on
the weak layer that occurs with one loading step, or tap. If you flip over the
block it may not necessarily be smooth. Drops in depth hoar will commonly look
rough when you examine the fracture.<br />
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Why is this important? Researchers have correlated sudden
fractures with skier triggering avalanches. Recent studies have shown that “Fracture Character is a valuable addition to the compression test score since most
failure layers of slab avalanches produce sudden fractures in compression tests”
(van <span style="font-family: font212;">Herwijnen and Jamieson 2004a). </span>Paying attention to whether your
compression test “pops” or “drops” can give you a better indication of whether
or not a specific slope has the potential to avalanche. This is also great
information to include when you send in your observations to the CBAC. </div>
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Remember that
performing snowpack tests is just one part assessing the snowpack. No one test can tell you if a slope is
stable. If you want more information on this topic check out <span style="font-family: font212;">Alec van Herwijnen and Bruce Jamieson’s 2004 paper titled Fracture Character in
Compression Tests. The chart below compares Fracture Character with shear quality and provides definitions for Fracture Character. </span></div>
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<span style="font-family: font212;">John MacKinnon</span></div>
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<span style="font-family: font212;">Works Cited</span></div>
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<span style="font-family: font212;"></span><span style="font-family: font212;"><span style="font-size: x-small;">Birkland, Karl "Comments on Using Shear Quality and Fracture Character<br />to Improve Stability Test Interpretation." <i>TAR Vol. 23. No. 2: 2004. </i></span></span><span style="font-size: x-small;"><br /></span></div>
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<span style="font-size: x-small;">van <span style="font-family: font212;">Herwijnen and Jamieson 2003. An update on fracture character in stability tests. <i>Avalanche<br />News</i> 66. Canadian Avalanche Association, Revelstoke, BC, 26-28.</span></span></div>
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<span style="font-size: x-small;">van <span style="font-family: font212;">Herwijnen and Jamieson 2004. Fracture Character in Compression Tests. <i>ISSW</i> 2004.</span><span style="font-family: font212;"> </span></span></div>
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<span style="font-size: x-small;">van <span style="font-family: font212;">Herwijnen and Jamieson 2004a. Fracture Character in Compression Tests." <i>ISSW</i> 2004.</span></span><br />
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CB Avalanche Centerhttp://www.blogger.com/profile/03786649465653688607noreply@blogger.com0