Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

Windy and snowy conditions will renew our concern for Wind Slab avalanches at upper elevations on Saturday. Look for actively blowing snow to help identify wind-loaded aspects; and deeper drifts that look smooth and "pillow-like" to locate features to avoid. As the day progresses, the wind speed may increase as it changes direction, creating slabs on a variety of aspects.

Problemi valanghivi

  • Wind Slabs

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

    Keep an eye out for wind-loaded features near ridgelines, rocky outcrops, confined gullies, or on convex slopes where you’re more likely to trigger an avalanche on Saturday. Shifting wind directions could result in Wind Slabs developing on different aspects than what you may be used to. Look for them on reverse aspects or cross-loaded mid-slope features by using visual clues such as identifying smooth pillow-like piles of snow or areas that look “fat”. Actively blowing snow, fresh cornices, or drifts behind objects can help you identify potential Wind Slab locations. If you suspect a feature to be wind-loaded, best to just steer around it at this time.

    (1/27/2023) Using uptrack tests in simple terrain to test for the reactivity of wind-drifted snow. Photo: Katie Warren

Avalanche Discussion

The East South zone should be favored during much of this next storm wave on Saturday, with areas both near and far from the crest squeezing out a few inches of snowfall. With cold temperatures expected, we could see some high snowfall-to-water ratios resulting in light and fluffy powder. As is often the case, the winds should be significant during this storm, easily strong enough to drift freshly fallen snow into unstable piles at mid and upper elevations. 

On Friday, NWAC forecasters traveled under sunny and clear skies in the Ahtanum Meadows area. The nice weather helped to moisten the snow, but not quite enough to tip the scales and produce wet avalanches. As they traveled higher in the terrain, they did find signs of wind-effected snow, but again, no Wind Slab avalanches. On slopes that see direct sunshine, those moist surfaces should freeze on Friday night, creating a firm crust for the new snow to fall on Saturday. Be sure to take a look at the bonding to this crust before committing to consequential terrain. Even a small avalanche could run far and fast, sweeping you off your feet in those types of conditions.

While weak snow was found above the MLK crust by NWAC forecasters in some locations, test results were not indicative of a widespread problem at this time. All the same, you will want to focus any snowpack tests and observations on the snow above this easily identifiable snowpack marker. 

If you get out into the mountains of the East-South, let us know what you see by submitting a public observation!

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