Lawinenlagebericht

Snake River Range

Bridger-Teton Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Triggering an avalanche 1-3 feet deep is possible today in steep terrain above 7,500'.  Riders triggered a number of slabs up to a foot thick yesterday, even in wind-sheltered locations. Consider the terrain below you and keep to lower angled slopes to avoid these avalanche concerns.  Avalanches are unlikely at the low elevations except in isolated pockets of very steep terrain.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Wind and storm slabs 1-2 feet thick formed 3 days ago above 7,500’ during a period of intense snowfall and strong winds out of the south and west. These slabs may be hard or soft and could still be triggered in very steep (>35°), wind loaded terrain like this one that was triggered in the Tetons yesterday.  Smaller slabs were triggered easily in more protected terrain yesterday as well. These slabs are sitting on top of a stout crust or near surface facets up to 9,000’.  Overall distribution of the weak layers across the terrain remains somewhat uncertain due to relatively few observations but the fact that some of these avalanches were triggered yesterday, several days after peak wind loading, should raise your hackles.  While these avalanches have been on the smaller side, they could bury you if you slide into a terrain trap.

    Be on the lookout for unstable wind drifted snow while traveling in the mountains and enter any consequential terrain cautiously. Recent avalanches, shooting cracks, and collapses in the snowpack are normally signs of instability but these signs may not be present given the current avalanche problems.  Also, recent reports indicate that wind slabs were triggered after multiple people had ridden a slope. Several inches of low density new snow may obscure surface clues of older slabs and require digging below the surface to verify their existence/reactivity. 

    (2/10/2025) Numerous small avalanches less than 12" deep were triggered on sheltered terrain in the trees.  It is likely that recent high winds drifted snow in areas were surface faceting was present on the older snow.

    Photo: BTAC

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    Weak snow that formed during a dry period in the second half of January has been buried 3-4 feet deep by snowfall from the early February storms. These slabs sit on a variety of interfaces, including crusts on solar aspects and facets on shaded aspects.The likelihood of triggering slabs at this interface has decreased over time and is now on the low end of the scale. However, activating this layer may still be possible in very steep terrain. Large triggers such as a surface avalanche, cornice fall, or multiple riders on a slope will increase the odds of impacting these layers in the middle of the snowpack. While the chances of triggering are low, it remains important to stack the odds in your favor by following safe travel protocol. Travel one at a time across steep terrain, use islands of safety, and communicate with your partners. This layer appears to be on it's way to dormancy.

Avalanche Discussion

From February 3rd-5th, temperatures were notably warm and rain fell up to 9,000’ in the Snakes. These conditions created a widespread surface crust that is present up to 9,000’ on most aspects. Then, a powerful winter storm beginning on February 6th brought about 20 inches of new snow and nearly 2” of water to the Snakes. Winds out of the southwest/west were notably strong during this period with gusts up to 60 mph! As a result, wind slabs have formed on many aspects above 7,500’ and are sitting on a good sliding surface. These slabs were most reactive three days ago, but a report of a human triggered avalanche that occurred Sunday (2/9) and the widespread reactivity that Alex found yesterday (2/10) in the Palisades indicates that this problem is still on the table. I found that the layer of concern would collapse in our pit but not propagate a crack. This uncertainty kept us off from riding out of a drainage that had overhead hazard. 

The January 31st interface consisting of crusts and facets remains on the radar. This layer has been buried by 3-4 feet of snow containing over 5” of Snow Water Equivalent (SWE). Since that layer was buried 7 days ago, temperatures have been warm, rain has fallen up to 9,000 feet, new snow and wind has stressed the snowpack, and temperatures have now cooled back down. In summary, the snowpack has been put to the test by the weather as well as recent smaller avalanches within the newest snow. While observations have been somewhat limited due to poor visibility, the lack of reported activity at these depths, combined with these weather factors paint a picture of improving stability at this interface.

If you see avalanche activity today, please submit an observation HERE. Observations allow everyone to gain a better and more complete understanding of conditions. Thanks!

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