Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
View on map

Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Multiple avalanches have been triggered over the last three days on weak layers buried 1-3 feet deep across all elevations and most aspects. These weak layers have increased in reactivity due to warming temperatures and wind loading, which will remain reactive today. In addition, new snow accumulation today with increased strong wind will stress buried weak layers and form fresh wind slabs. Use careful assessment of terrain and dig down to test weak layers before riding consequential terrain. 

The next storm system moves into the area today and tonight. Forecasted snowfall totals up to 10” by this evening with strong SW/W wind will increase avalanche danger througout the day. 

Avalanche problems

  • Wind Slabs

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

    Fresh wind slabs near ridgelines and exposed terrain have been formed recently less than 12 inches deep. S and W winds have deposited snow onto leeward terrain in middle and upper elevations. Wind speed will increase from moderate to strong with the approaching storm system. Monitor new snowfall accumulation during the day as new wind slabs form by the afternoon. Areas with wind slabs could also increase the chance of triggering a persistent slab. Look for obvious signs of instability such as cracking, stiffened surfaces, and drifts.

    (2/23/2023) Wind loaded terrain. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Weak layers buried on Feb 18th have increased in reactivity over the last several days with wind loading in the upper elevations and warm temperatures with solar influence in the low/middle elevations. Multiple D1.5-2 avalanches have been triggered on this new/old snow interface  such as No Name Canyon, Nugget, Avalanche Bowl. Soft and hard slabs range from 1-2 feet across all elevations, with depths up to 3 feet in the upper elevations in wind loaded terrain. Avalanches have been triggered on most aspects with the highest concentration from South to East. This new/old snow interface consists of facets and crusts. Additional snowfall today will add stress to buried weak layers, especially where fresh wind slabs form. Use careful judgment as these weak layers remain reactive today.

    Deeper weak layers still remain a concern, primarily the Jan 26th layer buried 2-4 feet deep. These layers have increased in reactivity in lower and middle elevations (Snow King, Taco Bell Couloir) where slabs have formed above weak snow.

    Pay attention to signs of instability such as audible collapsing of the snowpack and monitor the effects of new snow and wind. Your best line of defense against a persistent slab problem is to dig a snowpit in a representative location and perform some stability tests such as an Extended Column Test.

    (2/25/2023) 

    Persistent slab on Avalanche Bowl that failed on Feb 18th new/old interface. 

Avalanche Discussion

The last several days have seen numerous human triggered avalanches across all elevations and most aspects. This may come as a surprise since we haven’t seen any new snow accumulation. But, those other red flags play a significant factor with warming temperatures and increased wind recently. Remember that any changing conditions requires you to dial back terrain choices. This last storm cycle changed the structure of our snowpack, forming cohesive slabs with propensity to propagate above buried weak layers near the base of the snowpack in the low and middle elevations. Thus, avalanches have been triggered in areas we previously haven’t seen all winter. Previously unsuspected terrain may catch you off guard. Don’t let this happen. 

Today the next storm cycle will approach our Forecast Area. Avalanche danger will increase throughout the day. The amount of avalanche activity combined with more snow and wind should raise the hair on the back of your neck. Use careful decision making and monitor the new storm as avalanche danger increases. 

Regions covered