Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

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

630 AM Update - Above Treeline has been lowered to Moderate with less snow/wind than expected overnight.  Additional snow and wind over the next few days will incrementally load weak snow layers found in the upper snowpack.  Put a wide buffer between you and steep open slopes at mid and upper elevations, especially those that have been recently wind-loaded.  Red flags like whumpfing, collapsing or recent avalanches at any elevation should route you back to simpler terrain.    

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Another round of light snow, moderate ridgeline winds with a slow warming trend is headed our way tonight through Thursday.  Between a lack of direct observations above treeline and a potentially trickly snowpack, conservative terrain selection is warranted once again.  

    Thicker drifts and slabs are likely to be found on leeward slopes below ridgelines and exposed features in the alpine. Use extra caution anywhere you find wind-stiffened snow including on lower angle approaches because these slabs may be resting on weak, faceted grains and could break well above you. 

    (2/1/2022)

    Shooting crack on a wind-loaded feature at 5,800ft in the upper Salmon la Sac drainage.

    Photo: Ryan Minton

  • Persistent Slabs

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

    While collapses in the snowpack have been reported every day this work week by local professionals, no avalanches on these older snow layers have been observed, yet (see discussion below). Incremental loading events through the end of the week may tip those scales from one day to the next. 

    Persistent slab avalanches can break in surprising ways and be triggered on lower angle approaches. Travel cautiously while we gain more information on the distribution and likelihood of this tricky avalanche problem.  If you experience whumping or collapsing, assume you can trigger a persistent slab avalanche on nearby slopes.  Retreat to slopes 30 degrees or less and put a large buffer between you and larger avalanche paths.  

     

    (2/1/2022)

    A similar snowpack structure and avalanche concerns exists in the Stevens Pass zone: Very long shooting crack in a wind drifted slope on a north aspect at 4,000ft near Henry Creek. The slab failed in weak, faceted grains above a stout crust. The crack ran about 100ft long.

    Photo: Matt Primomo

Avalanche Discussion

630 AM Update - Above Treeline has been lowered to Moderate with less snow/wind than expected overnight. 

Starting at ~5500' and higher in the Washington Pass area you can dig down and find weak snow buried over the late January crust roughly 1-1.5 ft below the snow surface.  Areas further east in the zone will have less recent snow sitting over the late January crust. Below treeline, specifically in the 5,300-5600' range in the Washington Pass area,  large surface hoar was widely observed and subsequently buried by 6-12" of recent snow.  Only small loose dry avalanches have been noted in very steep terrain so far this week.  

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