Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

7:19a Update: CONSIDERABLE below treeline for warming temperatures and increased snow totals. Avalanche danger will increase as snowfall continues throughout the day. You could encounter a variety of new storm snow avalanche problems, ranging from dry loose to storm slab to wind slab, and avalanches could fail on a number of recent storm interfaces within the top couple feet. Today's a day to steer around steep terrain, especially when storm snow depths increase into the afternoon hours. 

Avalanche problems

  • Storm Slabs

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

    A range of avalanche problems, all common with new storm snow, could develop into dangerous avalanche concerns on Tuesday.  We're not quite certain how this storm is going to play out, but we expect at least a foot of low density powder by the end of the day. Sunday night we received a foot+ of low density snow, and on Monday we heard about wind slab avalanches in wind-affected areas, storm slabs failing on the new snow/old snow interface, and plenty of dry loose avalanches running with or without a human trigger.  Most of the avalanches were small. Some steeps just had low density powder, or "goose feathers" as one person called it, and the snowpack was relatively right side up with no slab development in some areas.

    Expect conditions to remain similar on Tuesday, but avalanches could grow in size and become more reactive as snow amounts increase. Wind slabs could develop more than they did on Monday, especially at higher elevations. Avalanches could fail within the new snow layer, they could fail on Monday's interface, or they could fail beneath Sunday's snow. This means an avalanche could easily be two feet or more in depth. There's a lot of uncertainty here, so be sure to stay on the conservative side during your travels. If you encounter any slablike qualities in the snow, steer around steep slopes. Slabs could be so soft that they may not be discernable from other snow in the vicinity. Don't ignore obvious clues like recent avalanches, whumphs, or long, shooting cracks.  If you have any doubts, steer clear of slopes steeper than 35 degrees.

    If you do get out on steep terrain, expect to trigger a dry loose avalanche at a minimum, so be prepared to manage sluffs on a slope and not get caught in one, as getting caught even in a small sluff could take you for a dangerous ride. 

    (3/22/2021) Storm slab avalanches like this old one near Tye Peak could occur on Tuesday. They could be more reactive in areas with additional wind loading.  Photo: Irene Henninger

Avalanche Discussion

Well over 2 feet of newly fallen low density snow will exist by the end of the day Tuesday. Tree well, or SIS concerns are elevated in these circumstances, so travel with a buddy and be very careful around trees and other subtle openings in the snow that could swallow you. 

A layer of surface hoar was buried Saturday night (12/18) as I found on my outing Sunday (HERE), and another observer reported on Monday (HERE). Snow layers on both sides of the buried weak layer were soft in most cases, so we are uncertain how reactive avalanches could be on this layer. Keep in mind that as more snow falls avalanches might fail easier than expected on this buried weak layer.

If you get out on Tuesday let us know what you encounter by submitting an observation HERE.

 

 

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