Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

7:30 AM update: Considerable avalanche danger is reaching down into the BTL as both water numbers and temperature have gone up slightly from the previous night's forecast. Avalanche danger will increase throughout the day as snow continues to pile up. This colder storm could dump larger amounts of low density snow than we're used to seeing with a storm this size, and your new snow avalanche problems could range from dry loose to storm slab, or wind slab at higher elevations. As the storm continues to rage on, your best bet is to steer clear of steep slopes and stick to lower angle terrain, especially as more snow accumulates.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    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 well over a foot of low density powder by the end of the day. Sunday night we received about 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 in neighboring zones.  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. 

    (1/4/2022)

    This old photo shows a storm slab avalanche breaking on a steep rollover, similar to what you might encounter on Tuesday. 

    Photo: Dallas Glass

Avalanche Discussion

You will find well over 2 feet of newly fallen low density snow 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 in the neighboring Stevens Pass zone Sunday (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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