Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Santa will bring a few inches of new snow to all the good little girls and boys at Snoqualmie Pass Christmas day. Windy and cold conditions should continue to load snow along ridgelines and exposed features. When you see blowing snow or notice drifts behind rocks, be leery of nearby steep slopes where the snow piles up deeper.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Windy conditions continue to persist in the Snoqualmie Pass area redistributing the recent snow. On Christmas Day a few inches will only add to the snow available for transport by the wind. Look for simple clues like blowing snow and drifts along the ridges to indicate which aspects may harbor wind slabs. By the end of the day Friday, you could find slabs 6-18” deep. If you suspect a slope is wind-loaded, steer around steep and convex features. Even though these slabs will likely be relatively small, they may run on a firm icy bed surface allowing them to travel quickly. At upper elevations, older deeper wind slabs could still exist. These potential avalanches are a few days old. However, recent (Tuesday-Wednesday) human triggered wind slabs at the Pass indicate that colder temperatures may allow these deeper pockets to remain reactive.

    (12/23/2020) Wind textured snow surfaces and drifts like these serves as great clues that the wind affected the snow pack and may have formed wind slabs on nearby slopes.

Avalanche Discussion

Windy conditions combined with cold temperature inversions just aren’t giving the snowpack what it needs to gain strength around the Pass. As a result, avalanche danger continues to exist on certain wind loaded terrain features. The Christmas storm won’t add sufficient new snow to notably increase the hazard. 

The upper snowpack consists of 6-12” of recent snow over a very firm and icy crust layer (12/21). We anticipate any avalanches to involve only the snow above this prominent snowpack marker. Last weekend a persistent weaklayer (12/13 facets/surface hoar) existed deeper in the snowpack. Recent rains and avalanches thoroughly tested this weakness. While you may still find it in isolated pockets, we don’t anticipate this layer being a concern in the near future. 

In some locations, the wind scoured slopes down to the icy crust creating very slick conditions. On this terrain, a simple slip could easily turn into an uncontrolled fall. Be ready for these icy patches. At lower elevations open creeks, holes in the snowpack, and numerous small trees may bar your way. Give yourself extra time to negotiate these challenging travel hazards. 

Happy Holidays from your friends at NWAC!

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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