Avalanche forecast

Togwotee Pass

Bridger-Teton Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
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Highlights

While a significant storm event has ended, conditions remain dangerous. Avalanches are most likely on slopes with wind drifting but could occur in wind-sheltered terrain. Triggering a larger avalanche breaking deeper within the snowpack is becoming less likely, but still poses a real threat. Safer conditions—and the best riding—can be found on gentler slopes (<30°) sheltered from the wind.

Avalanche problems

  • Wind Slabs

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

    Over a foot of new snow and moderate winds in the past 48 hours have created unstable conditions. Human-triggered avalanches are likely in steep, wind-loaded terrain at the mid and upper elevations. However, avalanches in sheltered terrain are possible today as well. Slabs will be up to 1 foot deep in sheltered areas and 2 feet deep in wind-loaded terrain. Dialing back slope angles to less than 30°, avoiding steep rollovers/gullies, and making conservative travel plans is a good idea today. The best way to avoid this problem is to avoid steep slopes or consequential terrain where you find indications of recent wind loading. Watch for snow that is denser than snow found on wind-sheltered slopes and tell-tale clues such as surface texture and a pillowed, drifted appearance. 

    A large natural avalanche was reported 48 hours ago on the east face of Two Ocean Mountain.

  • Persistent Slabs

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

    Weaker snow layers are now buried 2-3+ feet deep and should be on your radar. The consequences of triggering a large persistent slab increase as more snow has fallen. Avalanches involving these weak layers are most likely in terrain steeper than 30° on the compass's north half. New snow avalanches have the potential to step down to these layers, producing larger and more dangerous avalanches. While widespread avalanche activity involving weak snow near the ground is not likely today, significant loading has occurred over the past 48 hours. It is undoubtedly testing the strength of the lower snowpack. A conservative travel plan is a good idea today, given the uncertainty associated with the buried weak layers deeper in the snowpack.

     Yesterday, a rider was fully buried in the Palisades but was fortunately rescued, and the group was able to self-extricate. Though this circumstance occurred in a southern zone, it illustrates how unstable snow can be found even in places with a "friendlier" snowpack than Togwotee. People can ride many slopes across a zone or even the same slope before an avalanche is triggered.  Safe travel practices are necessary: good comms, checking out the snow you're riding (particularly north-facing terrain on even small but steep terrain features like those above creekbeds), steering clear of terrain traps, moving one at a time, and not exposing multiple people to steep slopes. 

    An avalanche failing on weak snow in the Togwotee area. Terrain traps like this gully should be avoided today.

Avalanche Discussion

FAQ's regarding the current snowpack

Q: How do avalanches fail on storm layers...and why?A: Multi-day storms like the one we're experiencing produce a variety of different snow crystal types. Some of these types don't get along very well and can behave much like a persistent weak layer. Like surface hoar, they're slippery. When these crystals are buried, they can remain preserved for longer than we expect and cause avalanches to fail within the new snow or at an interface between the new/old snow, particularly if storms start cool and end warm. Fortunately, the snowfall last evening did just that; however, weaker snow remains preserved in the upper portion of the snowpack from snowfall over the past 72 hours. Storm layers can be tricky, more challenging to identify, and capable of surprisingly wide propagation and remote triggering.  Expect to be surprised and build some safety margin to account for this uncertainty. 

Q: How do persistent weak layers like basal facets or buried surface hoar heal?A: One way is through mechanical compaction or compression. When a very thick, dense slab overlies a weak layer, the sheer weight of the slab begins to squash the weak layer. Like a group of introverts at a social gathering, at some point, they have no choice but to begin to connect. We're just starting to see this mechanism in some places where the primary weak layer near the bottom of the snowpack is showing signs of relenting under the weight of a thick slab. This layer remains shallowly buried and more developed in other areas (primarily the north half of the compass, rocky, or alpine terrain). As snow stacks up, these are the spots to keep on your radar. Continually probing the snow and looking beneath the surface to observe the snow you're riding is the only way to assess this problem and track it over time. 

You can submit observations and photos HERE or text 307-264-3050

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