Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

A welcome return to snow will also bring an increasing chance of avalanches. Winds may drift snow into stiffer slabs where you could trigger a small avalanche. Below corniced ridges and the base of cliffs are likely spots for these slabs to form. Steer around steep slopes if you see deeper drifts, textured surfaces, or blowing snow.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Visual clues such as actively drifting snow, textured surfaces, corniced ridges, and drift formations around rocks or trees can all point you to likely spots to trigger a wind slab. Lee slopes below ridgelines and the base of cliffs are common locations for wind slabs to form. You can use small test slopes to identify instability. Shooting cracks or mini avalanches on test slopes are bullseye signs of instability. Where you find these deeper drifts of snow on steep slopes, simply steer around them on lower angle terrain. 

    Winds won't be terribly impressive with this storm, but it will be enough to drift snow around. There isn't enough snow in the forecast for these wind slabs to be very big, but travel cautiously in extreme terrain where small avalanches can have significant consequences. In addition, these slabs may form over weak snow surfaces and slick crusts and be easy to trigger.

    (3/18/2022)

    You could trigger small wind slabs like this example on Monday. Notice the corniced ridges pointing to the wind loaded slopes.

     

    Photo: Andrew Kiefer

Avalanche Discussion

This incoming storm will favor the East South, and we may get up to 5-7 inches of snow by the end of the day on Monday. It isn't much, but it's a welcome change to the current conditions. Travel conditions may improve slightly, and there might be enough new snow to keep your snowmobile cool, but it probably isn't enough to leave the traction devices for slick surfaces at home quite yet. Open creeks, avalanche debris, and low snow cover will all still add complexity to your travel plans.

We are still assessing all the impacts of the storm and the natural avalanche cycle. But we expect a significantly stronger snowpack exists throughout the zone now that temperatures have cooled. And we expect the new Early February Crust will act as our new "ground" going forward. On Friday, in nearby East Central, I found widespread surface hoar and an inch of weak, faceted snow above 5700ft on the Early February Crust. These weak surfaces make for good sliding surfaces, and wind slabs or very small storm slabs may be touchy. Use test slopes and quick hand pits to observe how the new snow reacts. If it slides easily, avalanches are more likely. 

The snowpack has endured a beating over the past week with several inches of rain and warm temperatures. Reports of new large and very large avalanches from Ahtanum Meadows, Crystal Mountain, and East Central flowed in almost daily from January 21st through February 1st, when temperatures finally dropped below freezing. We are still looking for old crowns and avalanche debris to understand the full extent of this warm, wet storm and prolonged avalanche cycle. If you find evidence of an avalanche that we haven't logged in our avalanche observations, take a photo and let us know by submitting a public observation! Even if you don't see any avalanches, we'd love to hear about what you did find out in the mountains, and it helps shape a more accurate avalanche forecast. 

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