Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

By tonight, dangerous avalanche conditions will exist at upper elevations. New snow and wind will form soft slabs up to 18 inches deep above 9000 feet with natural avalanches likely. You will likely trigger avalanches on steep wind drifted slopes where unstable snow will be sensitive to the weight of a rider. On steep slopes protected from the wind, avalanches will be possible where new snow is sitting on older weak surfaces. Drifting snow and shooting cracks are indicators of unstable snow. Make conservative decisions around steep slopes once storm totals start adding up.

Avalanche problems

  • Wind Slabs

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

    Snow began to fall early this morning in the mountains. Up to 12 inches of snow is forecast to fall throughout the day at upper elevations with strong westerly winds and gusts up to 45 mph. If we receive forecasted amounts of snow, wind slabs will grow and could reach depths to 2 feet by tonight above 9000 feet. These soft slabs will be sitting on a variety of surfaces, including crusts on southerly slopes, faceted weak now on shady protected slopes, and windboard up high. Buried faceted snow will increase triggering sensitivity and likelihood in new snow . Watch for slab formation below ridgelines, around cliffs, and in steep gullies. If you find obvious clues like recent avalanches, actively blowing snow, and thick pillows, move to lower angle slopes.

  • Storm Slabs

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

    This problem will not show up until later this afternoon, particularly at lower and middle elevations. Once we have received around 6 inches or more, avalanches on steep slopes protected from the wind will be possible. Some uncertainty lies in the buried interface. In areas with buried faceted snow, storm slabs could behave unexpectedly, breaking farther and wider than expected. Triggering these avalanches could happen from the side or below steep slopes. Use caution around terrain traps and if you see shooting cracks, move to lower angle terrain.

Avalanche Discussion

Keep it simple today. We have high forecasted amounts of snow, strong westerly wind, and potentially weak interfaces. It's a tasty recipe for avalanches. There are 2 variables on my wind today:

  1. Storm Accumulation Totals. Keep track of how much snow is falling throughout the day. If storm totals come in at the high range by his evening, we could easily get over a foot of snow. Winds look to taper some but wind slabs will be sensitive and potentially grow to depths of 2 feet. Lower and middle elevation snow totals will play a big role in whether or not the storm slab problem will rear it’s head. If we get more than 6 inches, start thinking about avalanches on steep, wind protected slopes.
  2. Interface Bonding. Warm temperatures this morning should help new snow bond with surfaces. That said, several different surfaces have been left over from the month of high pressure. I’m most concerned with shady slopes where near surface facets are getting buried. Until we get a handle on the sensitivity and likelihood of triggering on different aspects and elevations, use caution around steep slopes today once snow accumulation starts adding up.

Shifting out of a low avalanche hazard mindset from the last month into assessment mode might take some effort. Dig around and see how new snow is bonding and monitor snow totals. Continue to travel one at a time, keep an eye on your partners and enjoy the powder this afternoon.

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