24-25
GNFAC Avalanche Forecast for Thu Feb 20, 2025
<p><span><span><span><strong><span><span>Persistent slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> - </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34267"><span><span><span><span><span><… and I remotely triggered</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> (from a distance) one of these slides on Lionhead yesterday 1-3 ft deep and 200 ft wide that broke on a weak layer of facets that formed on the snow surface in late January. This layer is easy to see in a </span></span></span></span></span></span><a href="https://www.mtavalanche.com/sites/default/files/snow_obs/2025-02/img_b2… wall</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. Another </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34264"><span><span><span><span><span><… avalanche was triggered remotely yesterday</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> east of Island Park in the Black Canyon area which is outside our forecast zone. It sounds similar to the one Dave and I triggered.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>The challenge</span></span></strong></span></span></span><span><span><span><span><span><span> is that these avalanches will happen well below treeline where the snow is relatively thinner and weaker. These areas can seem safer than higher elevations, BUT THEY ARE NOT. </span></span></span></span></span></span><span><span><span><strong><span><span>The other challenge</span></span></strong></span></span></span><span><span><span><span><span><span> is that this weak layer is not necessarily everywhere as Ian didn’t find it yesterday </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34260"><span><span><span><span><span><… in Bacon Rind</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. In popular riding areas, some slopes don’t have this weak layer because they were covered in wall-to-wall tracks in late January when that layer formed.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> - Wind slabs should be less sensitive today, but I bet you could still trigger some soft pillows of wind-deposited snow at upper elevations below cornices and ridgelines.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Conditions are dangerous and tricky today. Avalanches will be easy to trigger, and the avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>With so much new snow</span></span></strong></span></span></span><span><span><span><span><span><span> (2-4 FEET of snow in the last week), even light winds have plenty of snow to transport.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Wind slabs</span></span></strong></span></span></span><span><span><span><span><span><span> - Winds bumped up a bit midday yesterday at upper elevations and likely transported more snow, and local ski patrols have triggered fresh wind slabs nearly every day for about the last week. Skiers in the northern Bridgers spotted </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34271"><span><span><span><span><span><… least half a dozen slides</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> in Frazier Basin and active wind loading. They bailed on their original objectives and enjoyed great snow on slopes untouched by recent winds. Also yesterday, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34262"><span><span><span><span><span><… triggered a cornice</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> collapse on Saddle Peak which then caused a dry loose avalanche (sluff) to rumble over cliffs and create a large powder cloud. </span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Storm slabs and dry loose sluffs</span></span></strong></span></span></span><span><span><span><span><span><span> - The likelihood of triggering a soft slab or dry loose avalanche on non-wind loaded slopes is quickly going down, but the large sluff on Saddle Peak illustrates the potential.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Wet snow</span></span></strong></span></span></span><span><span><span><span><span><span> - Loose wet avalanches will be likely the first time all this powder is hit with warm temperatures and direct sunshine (</span></span></span></span></span></span><a href="https://youtu.be/E1nrxHzVsts?feature=shared"><span><span><span><span><s… describes it well in this video</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). Low elevations should see temps above freezing today, but clouds are supposed to limit the sunshine, so these wet slides may not be an issue until Friday.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Triggering a wind slab remains likely on wind loaded slopes where the avalanche danger is CONSIDERABLE. Non wind loaded slopes have a MODERATE danger with a decreasing potential for dry avalanches, but sometime maybe this afternoon or tomorrow an increasing potential for wet avalanches at low elevations.</span></span></span></span></span></span></p>
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Remotely triggered slide in Black Canyon
Forecast link: GNFAC Avalanche Forecast for Thu Feb 20, 2025
At Lionhead a weak layer generally 2-3 feet deep is obvious in this snowpit wall.
Forecast link: GNFAC Avalanche Forecast for Thu Feb 20, 2025
Weather and Avalanche Log for Thu Feb 20, 2025
Winds were a bit stronger yesterday midday
Remotely triggered the avalanche from 150 feet away. It broke 200' wide and 1-3 feet deep. It ran an estimated 200' vertical feet
Remotely triggered the avalanche from 150 feet away. It broke 200' wide and 1-3 feet deep. It ran an estimated 200' vertical feet
Forecast link: GNFAC Avalanche Forecast for Thu Feb 20, 2025
Avalanche on Saddle Peak, Bridgers
Note from BB ski patrol - skiers triggered a medium sized cornice fall that triggered a dry loose (sluff) avalanche that created large powder cloud.
Skiers triggered a medium sized cornice fall that triggered a dry loose (sluff) avalanche that created large powder cloud.
Forecast link: GNFAC Avalanche Forecast for Thu Feb 20, 2025
Frazier Basin Avalanches
Toured out to Frazier Basin and turned around seeing widespread avalanches and active wind loading. Despite our pits on the Throne the day before showing no weak layers, the amount of wind loading and potential for slabs over density changes gave us pause. Good skiing and sledding down low.