Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A week-long winter storm left us with lots of new snow and several potentially weak layers in the upper snowpack. As a result, you can still trigger avalanches, particularly at mid and upper elevations on steep, rocky, or wind-loaded slopes. Steer around open areas greater than 35 degrees and give the snowpack time to adjust.

Avalanche problems

  • Storm Slabs

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

    Several potential weak layers exist in the recent storm snow due to nearly a week’s worth of heavy precipitation, strong winds, and fluctuating snowlevels. This significant winter storm just ended and the snowpack needs time to adjust. While you may trigger a slab avalanche on any open slope greater than 35 degrees, pay particular attention to rocky slopes, convex rollovers, and areas the wind drifted the snow deeper. Small slope tests and simple handpits might not give you reliable information in these currently deep conditions. Instead, use patients and allow the snowpack time to gain strength. 

    Very windy waether along the Cascade Crest (Crystal, Chinook Pass, White Pass) formed stiff wind slabs at mid and upper elections. Watch for firm snow on some unusual aspects which can lure you far onto a slope before the avalanche releases. Give these hard wind slabs a wide berth.

    (2/17/2021) This natural avalanche likely occurred on Tuesday 2/16 during strong winds. Crystal backcountry. Bear Gap. SE 5900, SS-N-D2/R2-N 40cm deep and 150' wide. Photo: Tod Bloxham

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    The recent stormy weather only increased our uncertainty surrounding the potential of deep weak layers to produce avalanches. Observations on this layer have grown increasingly difficult as it continues to get buried deeper. Let the uncertainty and consequences of such a tricky avalanche problem shape your terrain choices. Consider staying out of the startzones for large avalanche paths and limiting the time you spend on the slopes below. Any slide on one of these persistent weak layers would produce a very large, destructive, and deadly avalanche.

    (2/3/2021) This natural avalanche likely occurred overnight on 02/02 in non-skier compacted terrain within Crystal Mt Ski Area. It failed on 1-2mm facets just above the 1/13 crust. 6300' NNE aspect. 85-95cm deep. Photo: Cyrstal Mt Ski Patrol

Avalanche Discussion

The next storm system should bring snow to the West South zone Thursday. The limited daytime snow accumulations should not significantly impact the avalanche danger. As easterly winds increase during the day, you could find thin slabs forming on the lee sides of exposed features. 

This recent storm cycle was a doozy. Paradise received more than 6” of water and saw its snowpack grow by more than 3.5ft since 2/11! While Crystal, Chinook Pass, and White Pass received less snow, they each recorded 4-5’ feet during this cycle. All this new snow sits above the 2/11 interface. Weak faceted grains were observed at this layer and produced several surprising avalanches in the White Pass and Crystal areas early in the storm cycle. Now, this layer lies 3-4’ below the surface in most areas. Deeper still sits the mid-January facet/crust layer (6-8’). This persistent weak layer produced numerous large and surprising slides over the past two weeks. While we don’t have any recent avalanche observations on this layer, that may only be because of the stormy weather. Observing and tracking this layer has become incredibly challenging. 

With all the recent snow you may find that tree wells and deep snow immersion pose one of your greatest risks. Please follow the link for more information. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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