Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Periods of intense snowfall and wind will continue the threat of triggering slab avalanches, especially at upper elevations. You're most likely to find trouble where the wind has formed fresh drifts or stiffened the snow in the upper 6-12 inches of the snowpack. Multiple reports of avalanches less than 12 inches deep triggered in steep wind-loaded terrain over the last several days mean that older slabs may also remain sensitive. While less likely, new snow atop these older slabs could break up to two feet deep. New snow may also sluff easily, and cautious route-finding and conservative decision-making are essential, particularly in upper-elevation terrain.

Avalanche problems

  • Wind Slabs

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

    Recent winds have raked this forecast area, building wind slabs in exposed terrain (see photo). These slabs will be thicker and more abundant as you climb in elevation. Windier locations like low saddles and mouths of main drainages are also likely to have denser, newly formed slabs sitting atop older wind slabs that still might remain sensitive to your weight. Loose snow movement is also likely in steep terrain, and the weight of this snow movement may also pose a threat for triggering a larger slab avalanche in adjoining terrain features (i.e. sidewalls of steep, tight terrain). 

    Sensitive slabs have been reported on steep E to NE aspects from 9,500’ to 11,400’. These reported avalanches have been less than 12 inches deep in isolated terrain features (Cave Couloir, Taylor, West Hourglass Couloir), and pose a larger threat in consequential terrain (Wister). Warming temperatures and changes in snowfall may make these slabs even more reactive. Also bear in mind that new snowfall can mask previously wind-loaded terrain and make unstable features harder to identify.

    (1/8/2023)

    Cave Couloir wind slab: 10,250' E apect

Avalanche Discussion

Each new storm buries a new interface to think about. Depending on the character of the older snow, the bond at this interface can vary significantly in strength. Generally speaking, as the complexity of the snowpack increases, it becomes more and more difficult to confidently assess the stability of a given slope.  Fortunately, the Teton trickle has provided very few days of clearing throughout the start of this new year. That being said, there are still interfaces subtly being buried, and additional snow on weak layers harbored on some aspects in the middle to upper elevations. Though they haven't made any appearances in a while, I still seek them out in the terrain I enter and assess things with a guilty-until-proven-innocent mindset. 

You can try to limit some of the uncertainty present when dealing with complex avalanche problems by keeping track of these layers in the areas that you frequent. The challenge this poses is no small task. In the Greys Zone over the past week, I've found snowpack depths ranging from 12 inches to over 3 feet deep; one sub-zone had widespread melt-freeze crust from a recent clearing above 9,000 feet, even on northerly and shaded aspects, while another held soft, dry snow still even in the lower elevations. I've found buried surface hoar, thick layers of facets in the middle and base of the pack, and also thick crusts at the base of the pack with very little facet development-literally every condition in the book. Microclimate zones exist within each larger range (whether it's the west vs east of the Tetons, the differences along the Continental Divide at Togwotee, or the Salt Range vs Wyoming Range of the Greys), and each is worth getting to know closely if you are frequenting it.  With any snowpack, it's very important to recognize when you are dealing with a problem that is more complex than we as humans can typically fully understand. We can still make our best assessment with all the tools available to us, and our best bet is to always step back if surprised by something. Pad your uncertainty by building healthy margins for error into your travel practices, and tread lightly with rapidly changing snow conditions today.

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