GNFAC Avalanche Forecast for Fri Feb 7, 2025
<p><span><span><span><span><span><span>It’s been a wild week of unusual weather - with hurricane force winds, winds blowing from unusual directions, both very warm and very cold temperatures (sometimes right next to each other with crazy strong temperature inversions), and periods of rapid snowfall. This all came after some new weak layers formed and it has left us with quite a variable snowpack.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Now it’s snowing again. This will both add load to the snowpack and make it harder to visually identify what’s been going at the snow surface over the last week (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=pwAambVPOeg"><span><span><span><span><s…’s video</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> from Blackmore yesterday).</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Unusual weather leads to unusual avalanches. This has certainly been the case over the last couple days. </span></span></span></span></span></span></p>
<ul>
<li><span><span><span><span><span><span>On Wednesday, Big Sky Ski Patrol intentionally triggered an avalanche with explosives on a slope loaded by the strong south winds that broke up to 7 feet deep, breaking on the old snow surface from dry weather in late January. They haven’t seen an avalanche like that on that slope in 40-50 years. (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34027"><span><span><span><span><span><…;, </span></span></span></span></span></span><a href="https://www.kbzk.com/news/local-news/avalanche-triggered-during-mitigat… story</span></span></u></span></span></span></span></span></a></li>
<li><span><span><span><span><span><span>Also on Wednesday, skiers triggered many storm slab avalanches in the new snow at low elevations on </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34015"><span><span><span><span><span><…. Ellis</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> and in the </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34013"><span><span><span><span><span><… Range</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>.</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>There have also been plenty more typical avalanches on wind-loaded slopes below ridgelines across the advisory area (examples from near Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/avalanche-north-crown-butte"><spa…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/scotch-bonnet-north-avalanche"><s…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/natural-avalanche-mt-henderson-ne…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/natural-avalanche-miller-ridge-ne…;), </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33978"><span><span><span><span><span><…;, and the </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/wind-slab-crown-hourglass-couloir…;).</span></span></span></span></span></span></li>
</ul>
<p><span><span><span><span><span><span>Very strong winds and winds from unusual directions (out of the east) have loaded slopes that aren’t usually loaded, so be on alert for wind loading everywhere. Additionally, be on alert for slides on lower elevation slopes that usually aren’t much of a concern. In some cases, with the strong inversions mid-week, they may have touchier conditions than higher elevation slopes (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34031"><span><span><span><span><span><…;). </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>With lots going on in the snowpack and it being loaded again, avalanche conditions are dangerous and cautious route-finding is required. Avalanches could break as </span></span></span></span></span></span><span><span><span><strong><span><span>Wind Slabs</span></span></strong></span></span></span><span><span><span><span><span><span> either in the new snow or from snow drifted earlier in the week, </span></span></span></span></span></span><span><span><span><strong><span><span>Storm Slabs</span></span></strong></span></span></span><span><span><span><span><span><span> as snow piles up during intense precipitation today, or</span></span></span></span></span></span><span><span><span><strong><span><span> Persistent Slabs</span></span></strong></span></span></span><span><span><span><span><span><span> on the weak layers that formed during the dry period in late January.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Today, the avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
Most notable test result was ECTP16 down 35 cm on a layer of surface hoar. Photo: E Heiman
Forecast link: GNFAC Avalanche Forecast for Sun Feb 9, 2025
Most notable test result was ECTP16 down 35 cm on a layer of surface hoar. Photo: E Heiman
Poor Test Scores on Mt. Ellis
Dug on a NE aspect at about 7800’ on Mt. Ellis. Noticed pretty significant wind loading/cornice development from yesterday and was easily able to get small cornices to break off. Most notable test result was ECTP16 down 35 cm on a layer of surface hoar. Besides the concerning surface hoar layer the snowpack was generally right side up and seemed pretty solid. Photo of pit profile attached.
Several Older Wind Slab Avalanches on Blackmore
The wind had hammered snow surfaces at all elevations above tree line on Mount Blackmore. There was evidence of several R1-2/ D1-2 wind slab avalanches that likely ran this weekend on the east face of Blackmore.
Three to four inches of new snow from yesterday sat on top of the dust layer that got deposited across most of the forecast area on Monday and Tuesday. Photo: GNFAC
There was evidence of several R1-2/ D1-2 wind slab avalanches that likely ran this weekend on the east face of Blackmore. Photo: GNFAC