GNFAC Avalanche Forecast for Sun Mar 16, 2025
<p><span><span><span><span><span><span>Winds have increased to strong from the west and southwest after multiple days of calm conditions. These winds are drifting 10-20” of new snow (1-2" of snow water equivalent) from the last couple days into fresh cohesive slabs up to 2 feet deep. </span></span></span><strong><span><span>Wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are easy to trigger and dangerous avalanche conditions will develop. Heavy snowfall is possible today and strong wind will continue, so the size, likelihood and distribution of avalanches will increase through the day. </span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Loose snow avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>and </span></span></span></span></span></span><span><span><span><strong><span><span>storm slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>are also possible and can easily run long distances on the crust below the new snow (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=6pLrdFVFpdE&list=PLXu5151nmAvToI_ir…;. These are especially dangerous if they drag you into rocks, trees or over a cliff. On Friday in the Centennials near Island Park Mark saw a larger avalanche that broke on or under the crust below the new snow (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=3ziK29iO3zQ&list=PLXu5151nmAvToI_ir…;
<p><span><span><span><span><span><span>An additional problem south of Big Sky to West Yellowstone are deeper </span></span></span></span></span></span><span><span><span><strong><span><span>persistent slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>breaking 2-5 feet deep on the weak snow that was buried in late January. On Friday in Taylor Fork a snowmobiler triggered a 2-3 foot deep hard slab on a short, steep slope with a relatively shallow snowpack (2 to 5’ deep)(</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34610"><span><span><span><strong><span…, photo and obs. from my visit to the avalanche in Taylor Fork yesterday</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). These types of slides have become increasingly less frequent, but we could see more with the added weight of new snow over the next few days.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Today the avalanche danger is CONSIDERABLE. Choose terrain carefully. Avoid steep wind-loaded slopes. Consider avoiding all slopes steeper than 30 degrees as heavy snowfall and strong wind increase the chances of human-triggered and natural avalanches through the day.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Less snow is expected near Bozeman and Big Sky compared to the southern half of our forecast area, and less snow fell over the last couple days (6-16" = 0.7-0.9" snow water equivalent). Strong wind today will create fresh slabs that are easy to trigger, making human-triggered </span></span></span></span></span></span><span><span><span><strong><span><span>wind slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>likely. Yesterday there were a couple fresh natural wind slab avalanches reported in the northern Bridgers (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34607"><span><span><span><strong><span…;). Today, wind-loaded slopes could be widespread and the size of slabs will grow due to continuing steady moderate to strong winds. Be on the lookout for fresh drifts on all aspects and elevations, not just the typical areas like near ridgelines.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>On non-wind-loaded slopes </span></span></span></span></span></span><span><span><span><strong><span><span>loose snow avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>are possible and can run long distances on the crust below the recent snow. These can be easy to identify and manage, but can easily knock you over and be dangerous above cliffs, rocks or trees (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34608"><span><span><span><strong><span…’s observation from Bridger Peak</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>).</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Be cautious and avoid wind-loaded slopes today. Watch for a textured or pillowy snow surface, or cracking out from your feet or skis as signs of wind-loading. Avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on other slopes near Bozeman and Big Sky.</span></span></span></span></span></span></p>
"Today I triggered a D1 dry loose avalanche on a E facing 35 degree slope, 9300 ft on Mt Henderson. The new snow is very low density and is not bonding well to the old interface. I also observed some more dry loose activity/small wind slabs on Sheep Mt, NE facing, 10400 ft."
Forecast link: GNFAC Avalanche Forecast for Sun Mar 16, 2025
On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
Forecast link: GNFAC Avalanche Forecast for Sun Mar 16, 2025
On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
Forecast link: GNFAC Avalanche Forecast for Sun Mar 16, 2025
Island Park soft slabs
We observed two very recent natural storm slab avalanches about a 1.5 feet deep. One of them entrained a significant amount of snow an ran a long ways.
Mar 15 Winds in the Frazier Basin zone were stronger than expected with moderate to strong gusts at the ridge, increasing through the day. We noticed two large windslab pockets that had released since yesterday’s snow. One at the base of Hardscrabble Peak on a N aspect, the other in one of the SE facing gullies that access the Peak 9299/Hollywood Headwall ridge (see photo).