Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Upper elevation wind loaded terrain will be where triggering an avalanche is most possible. Look for obvious signs of unstable snow such cracking, stiffened surfaces or large pillows/drifts. These wind slabs will increase in size and reactivity the higher you travel in elevation. Monitor snow surface conditions by the afternoon as the sun increases reactivity of recent snow on southerly slopes, especially near rock and cliff features. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The primary concern will be wind slabs that formed over the last 2-3 days. Winds were actively loading terrain ranging 20-30 mph from primarily the west and southwest. Slabs will be found on leeward and cross loaded terrain in the upper elevations 1-2 feet and possibly 3 feet in isolated areas. Signs of instability could be less obvious than previous days, but still possible to trigger once you commit to a slope. We just received a significant amount of snow that is still settling. Steep and confined features, such as couloirs, as well as terrain off ridgelines should be assessed thoroughly for any reactive slabs.

    Deep wind slab avalanche on leeward terrain off a ridgline. This avalanche failed directly on a large pilllow/drift. 

    (3/7/2024) Photo: Colin Boeh

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Weak snow formed in December is persisting 3-5+ feet deep below hard slabs. These weak layers have been tested over the last week with 70” of snow and 7.5” of SWE since March 1st (Raymer weather station, JHMR). A couple avalanches were reported during this storm cycle that potentially failed on these weak layers (Treasure Mountain). Large loading events and large triggers, such as cornice falls, have been able to produce very large avalanches on these layers. The impact of a rider triggering these layers is unlikely. Still the primary terrain that is most hazardous includes very steep, hanging snowfields above cliffs and rocky or notably shallow slopes. Keep in mind that a large wind slab release or cornice fall will make it possible to trigger one of these very large avalanches.

    (3/6/2024) Crown of a very large (D3) avalanche in the South Fork Teton Canyon. This slide was triggered by a cornice fall on the right side of the photo. The avalanche occurred in steep, rocky NE-facing terrain at 9400' and ran 2400' to the valley floor and broke many mature trees.

    Photo: Cameron Galt

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Clear, sunny skies will decrease stability on southerly aspects by the afternoon. Watch for snow surfaces to become wet and easier to penetrate as a sign of wet loose avalanche potential. These avalanches will be small but could knock you off your feet or machine in steep terrain. The snow around rocks and cliffs will warm up earlier in the day resulting in more activity. Upper elevation wet loose potential will be isolated to slopes direcetly facing the sun around that steep, rocky terrain.  

    Cornice Falls: Give cornices a wide margin of safety and be careful along ridgelines as they can break further back than expected. Limit exposure on terrain under cornices especially after the recent loading event and warming trend now. 

Avalanche Discussion

February and March have made a significant transition to a more typical mid winter snowpack where new snow instability is the primary avalanche problem. Persistent weak layers are getting buried deeper each storm becoming more difficult and unlikely for a rider to trigger with their weight alone. A significant amount of snow has fallen over the last week, with breaks between storms creating short lived weak interfaces. As the recent snow settles, reactivity decreases. We have seen positive trends in this decreased reactivity. But knowing exactly when conditions simmer down can be difficult to predict. Continue to monitor the new snow instability and keep a close eye out for signs of wind slabs. 600 total miles of wind was reported 3/6-3/7, exceeding the thresholds of when we typically see reactive wind slabs develop. Use extra caution in your snow assessment if traveling in the higher elevations or more extreme terrain. 

Snowfall since 2/26: 90” 9.1” SWE (Raymer, JHMR)

Snowfall since 3/1: 70” 7.5” SWE (Raymer, JHMR)

Regions covered