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

Human triggered wind slab avalanches were reported yesterday in wind loaded upper elevation terrain that will remain reactive today. Look for obvious signs of instability on wind drifted slopes from strong NE winds such as cracking, stiffened snow surfaces, and large pillows/drifts. Watch for decreased stability on W-S-E aspects facing the sun in the lower and middle elevations by the afternoon.

Avalanche problems

  • Wind Slabs

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

    Recent snow combined with moderate to strong NE wind formed slabs up to 1-3 feet deep in upper elevations. A skier was caught and carried by a 3 foot wind slab yesterday on No Name Traverse. These slabs sit on a fairly widespread crust formed prior to the recent snow on W-S-E aspects up to 10,000’. Signs of instability on wind drifted snow were very apparent yesterday. Multiple small, shallow wind slabs were triggered as well. NE wind is atypical for this area, so look for wind loaded slopes in unusual areas. Obvious signs of instability may not be apparent as yesterday. Look for unstable snow on wind loaded slopes off ridgelines, convex rollovers, below cliffs, and between confined rock features such as couloirs. 

    Cornice Falls: Warm temperatures today will increase the sensitivity of cornices. Give cornices a wide margin of safety and be careful along ridgelines as they can break further back than expected. Limit exposure under cornices, particularly in the afternoon, as natural cornice falls are possible. Cornice falls are the most likely way to trigger a very large deep persistent slab avalanche.

    (3/14/2024)

    Cracking, an obvious sign of instability on wind loaded terrain.  This unstable snow was found on leeward terrain (SW aspect) off a ridgeline at 9,000'. 

    Photo: Alex Drinkard

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–1.5

    Warm temperatures combined with strong solar influence will decrease stability on W-S-E aspects in the middle and lower elevations. Triggering a wet loose avalanche will be most likely on steep slopes facing the sun in the afternoon. 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. Look for obvious signs of snow becoming wet such as roller balls and pinwheels.

  • Deep Persistent Slabs

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

    Weak snow formed in December is persisting 3-5+ feet deep below hard slabs.The early March storm cycle produced very large avalanches on these weak layers, with the last reported avalanche on 3/5. These occurred on heavily wind loaded terrain and below cornices. The impact of a rider triggering these layers is unlikely. Still the primary terrain that is most hazardous includes very steep, unsupported slopes above cliffs and rocky or notably shallow slopes. Thin spots in the snowpack are more likely to act as trigger points in these locations. Keep in mind that a cornice fall or surface snow avalanche will make it possible to trigger one of these very large avalanches. 

    (3/5/2024)

    Very large persistent slab avalanche that failed during the early March storm cycle. This terrain characterizes where this problem is most relevant. Very steep, unsupported slopes above cliffs. Also note the large cornices and potential trigger. 

Avalanche Discussion

Yesterday the recent snow got worked over by the strong NE winds and solar influence on southerly aspects. Strong NE winds were reported at JHMR Summit (10,450’) above 30 mph over a 12 hour period from the night of the 13th to morning of the 14th. As mentioned above, signs of instability and human triggered avalanches were reported yesterday. These wind slabs will remain reactive today. Seek more sheltered terrain if you encounter wind loaded slopes. Increased temperature and strong solar influence could increase reactivity of these slabs by the afternoon. Spring like conditions will develop today creating wet loose avalanches on southerly aspects. Although unlikely, wet loose avalanches could be possible in very isolated areas of the upper elevations around rock features. A solid freeze last night and NE wind 10-15 mph in the upper elevations will help keep snow surfaces cool in upper elevations 

Over the next several days we will enter a drier warming trend. With the arrival of spring, folks will be getting out the door earlier in the morning for alpine starts when forecasts are not published yet. In these cases, remember to do your research on changing weather conditions before entering the mountains. Slight changes in wind direction and speed will significantly help inform your travel plans and objectives. Check recent observations to stay updated on current conditions. Remember to assess new snow instability yourself and continue to submit observations to improve information sharing for the community. Thank you and enjoy the sunshine today.

A large to very large avalanche was reported on Fossil Mountain yesterday. Specific details of the avalanche are unknown due to it's remote location. This avalanche potentially failed on persistent weak layers. There's a lot of uncertainty in how this current warming trend will influence the Deep Persistent Slab problem. Use extra caution as temperatures continue to increase this weekend into early next week in terrain highlighted above where this problem is most hazardous. 

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