Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Very large and deadly wet avalanches could run to valley bottoms. Avoid all steep slopes and stay well out from under any areas where slides could come from above. Up to 3" of rain will fall on previously dry snow to all elevations.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–3

    Expect a range of dangerous wet avalanches. Very large slides could start at upper elevations and run to valley bottoms. Avalanches starting at lower elevations could still be big enough to bury or kill you. Stay well away from and out from under slopes that are 35 degrees and steeper.  Don't linger or stop in runout zones of big avalanche paths. Avalanche activity may peak overnight but could extend through Wednesday morning. 

    On Tuesday, WSDOT forecasters reported a very large (D3) avalanche that ran to the valley floor near Highway 2 on a south aspect of Rock Mtn. We could see more of these by Wednesday as rain falls to the highest elevations. Other very large, deep avalanches have recently occurred in the neighboring Snoqualmie and East Central zone. We have limited information and access to the Stevens Pass area.

    (1/18/2021) An example of a very large (D3) wet avalanche debris pile in the Wellington slide path from January 2021. Photo: Will Govus

Avalanche Discussion

Rain began in the early hours of the 11th and could total up to 3" by Wednesday. This is falling on a mostly dry snowpack that's still settling and adjusting after another massive storm. Forecasters at Stevens Pass Mountain Resort measured 82" of snow accumulation in 72 hours between January 5 and 7th. Check out this observation from the 8th. We have lots of uncertainty in the current conditions.

There is minimal access to most of the zone, weather stations have been down, and information is limited. Infrastructure and highway crews are still recovering from the historic storm last week. Last Friday, WSDOT crews reported triggering D3.5 avalanches on the pass with control work, which left debris 60ft high over the road. On Thursday, they reported multiple natural avalanches D2.5-D3 in size that hit the closed highway west of the pass. Once the storm ended, WSDOT reported over 208 debris piles up to 15 feet deep on Highway 2 in Tumwater Canyon alone. Several slides ran into the river and ten of them were very large. Prior to the storm on the 6-8th, observers noted a couple of buried layers of large, faceted stellars and surface hoar. These layers are probably 4-5ft below the surface now and could be weak layers for slab avalanches.

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