19-20
Collapse near Ross Peak
After getting unstable snowpack test results, skiers on 3/27/2020 got a collapse on facets over a crust buried about a foot deep, near Ross Peak in the Bridger Range.
GNFAC Avalanche Forecast for Sat Mar 28, 2020
<p>Avalanches can break today on weak layers buried 1-2 ft deep underneath this week’s snow. These weak layers have been found across southwest Montana and we’ve seen quite few avalanches breaking on them (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log">Weather and Avalanche Log</a>). On Thursday, skiers in Hyalite triggered a slab that broke 2 ft deep on a north facing slope in the Twin Falls basin (<a href="https://www.mtavalanche.com/images/20/skier-triggered-slide-hyalite">ph…;).</p>
<p>Doug and Dave took down the Taylor Fork and Lionhead weather stations yesterday. In both areas they got unstable snowpack test results on the weak layers in the upper snowpack (<strong><a href="https://www.youtube.com/watch?v=ZkyjbN1sWl0&list=PLXu5151nmAvSbcbVf…;). In the Taylor Fork the weak layer was sitting above a crust, while there was no crust at Lionhead. In some area the weak layer is near surface facets and in others it is surface hoar. The grain type of the weak layer doesn’t really matter. The important thing is that if the weak layers are there, they’ll be just beneath the new snow. Use an Extended Column Test to look for and test the weak layer before getting onto a steep slope. Yesterday, multiple groups got unstable test result across the area and backed off steeper lines. Follow their example. The more deeply these weak layers are buried, the more problematic they will be, which means that wind-loaded slopes remain more worrisome than other slopes (<a href="https://www.mtavalanche.com/images/20/cornice-growth-bridger-ridge"><st…;).</p>
<p>Clouds and temperatures in the 20s F should keep the wet snow at bay today.</p>
<p>The <a href="https://covid19.mt.gov/Portals/223/Documents/Stay%20at%20Home%20Directi… at home order</a> that goes into affect today across Montana specifically discourages “outdoor recreation activities that pose enhanced risks of injury or could otherwise stress the ability of local first responders to address the COVID-19 emergency (e.g., backcountry skiing in a manner inconsistent with avalanche recommendations or in closed terrain)”. Get out and enjoy the fresh air, but please dial back your objectives, slow down, and work to minimize the risk of injury or need for rescue.</p>
<p>Throughout our advisory area, the avalanche danger is rated MODERATE.</p>
<p>We plan to end daily avalanche forecasts on Sunday, April 5<sup>th</sup> and continue with general bulletins every Monday and Friday through April. We have taken down most weather stations and will no longer receive observations from guides and ski patrol. We need help gathering field data. Please send us your observations no matter how brief. You can fill out an observation form, email us (mtavalanche@gmail.com), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
The avalanche education season is winding down, but you can still find a few courses offered by other providers on our website on the Events and Education Calendar.
Skier triggered slide in Twin Falls Basin
From obs: Small D2 avalanche triggered while assessing the slope on a due-north facing aspect on a roughly 35-40 deg. slope at ~9000 ft. near Arden Lake in the Twin Falls drainage off the Main Fork of Hyalite. .... Had about a 2 ft deep, 30 ft-long crown. The bed surface was not clearly a sun-crust and was of low quality and remained relatively soft to ski on after the slide. There were crystals above that may be classified as facets, maybe 1mm dia. It seemed to have gone on a compacted layer that the 18" of fresh had weighted."
Natural avalanche in Cooke
From email on 3/27/2020 : "natural slab avalanche I observed today near Cooke City. An easterly aspect around 9,400'. I'd estimate the crown to be 2-3' deep and about 100' wide. Looks like it was triggered by a cornice fall (2-3 days ago?)."
Photo: B. Fredlund
Forecast link: GNFAC Avalanche Forecast for Sat Mar 28, 2020
Main Fork of Hyalite 3/27.
From obs: "This slide popped on a N aspect at 9000', ranging from 18-30 inches deep... it slid on a crust." Photo: N. Iltis
Forecast link: GNFAC Avalanche Forecast for Sat Mar 28, 2020GNFAC Avalanche Forecast for Sun Mar 29, 2020
Today on the east side of Lionhead Ridge we found a layer of weak, near-surface facets buried under a foot and a half of new snow. This is definitely something to watch out for especially on wind-loaded slopes. Photos: GNFAC
Forecast link: GNFAC Avalanche Forecast for Sat Mar 28, 2020