Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Forecast updated at 6:15 AM January 12th: A widespread and very dangerous avalanche cycle is expected at all elevations with the most dangerous conditions expected as snow transitions to rain during the morning hours. More than 20" of very heavy snowfall fell at Snoqualmie Pass and snow will transition to rain at all elevations during daytime hours. Conditions will be dynamic and unmanageable Tuesday, and travel in avalanche terrain is not recommended. 

 

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–3

    Rain will rapidly destabilize the snowpack Tuesday. Wet avalanches will likely run naturally. With 20" or more of recent snow on the ground at all elevations, very dangerous wet avalanches will occur when the 1.9" of precipitation transitions to rain.  Depending on how much snow accumulates before the eventual transition to rain, these avalanches could be very large. Some of these wet avalanches may be glide avalanches, triggering the entire snowpack above a smooth rock slab. Avoid all locations where avalanches may start, stop, or run on Tuesday.

    A very large avalanche in Heather and Clark canyon at Mt Hood shows the power of wet snow.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–3

    Heavy dense snow will load lower density layers from earlier in the storm cycle, creating widespread slabs 2 ft deep that you can easily trigger within the recent storm snow. Given the heavy, dense snow these slabs will have plenty of force to harm or kill you. Depending upon how much snow accumulates before a transition to rain, a storm slab could become very large. Firmer over weaker snow will confirm the very dangerous conditions. A rapidly ascending rain from late morning onwards may confine storm slabs to the highest elevations above treeline, transitioning the avalanche problems from dry to wet. Keep things simple and avoid all avalanche terrain.

    Example: storm slab avalanche.

Avalanche Discussion

The Snoqualmie Pass area picked up more than 20" of snow with snow levels between 2500 and 3000 ft on Monday and Monday night. We're expecting up to 6" of snow Monday morning before a the snow line retreats to higher elevations. This transition will be very dangerous with widespread large or very large avalanche activity that should keep you out of avalanche terrain.

Below the new snow, NWAC professionals in the Stampede Pass area and several avalanche classes in the Alpental Valley over the weekend found a well-settled snowpack that keeps us focused on the snow falling within this storm cycle, although an isolated (and very large) avalanche failing down to the January 1st crust is not out of the question.

Tuesday represents a drastic uptick in avalanche danger. Shallow wind slabs have been the story for the last several days. We received a few reports of small skier triggered wind slabs over the weekend.

If you travel in non-avalanche terrain, keep in mind that despite the generally deep and strong snowpack around Snoqualmie Pass, open creeks will open further to become a more significant hazard. Seek out safe crossings and give yourself extra time to navigate this non-avalanche hazard. 

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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