Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

You can trigger an avalanche at mid and upper elevations where wind transported new snow forms unstable slabs. Monitor the wind loading pattern in the terrain you travel. Identify slopes downwind and look for smooth or pillowy-looking snow. Steer around steep, freshly loaded slopes.

Problemi valanghivi

  • Wind Slabs

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

    Sunday is on tap to be a repeat of the past few days with similar weather and avalanche conditions. Moderate to strong winds and a few inches of new snow won’t do much to increase avalanche danger but it isn’t really dropping either. There is just enough snow and wind to keep fresh slabs in play on specific terrain features, especially steep or unsupported areas just below ridgelines. 

    Take note of the pattern of wind loading by using scoured snow surfaces, cornice-like features, and changes in snow texture to suss out where wind slabs could be hiding. Blowing snow might just show you exactly which slopes are loading up. Evaluate the bond of wind slabs before committing to steep terrain with slope tests and hand shears - or just use a lower angled line to bypass steep wind loaded features.

    (1/7/2023)

    A human triggered wind slab avalanche that was reported today from near Mt. Rainier. 

    Photo: NWAC Public Obs

Avalanche Discussion

Yet another warm weather system exits the Cascades this evening. Observations include a single human triggered avalanche in the Tatoosh. It occurred on a convex, wind loaded slope near treeline. Saturday also brought reports of fresh but shallow wind slabs in the Crystal backcountry. Wind gusts to 60mph around Crystal did a great job of blowing around a few inches of new snow and whatever older snow is still available for transport. 5” of new snow was reported at Paradise.

Intact buried surface hoar was identified in the White Pass backcountry this week. It was about 7" below the surface on a variety of aspects at mid-elevation. The same buried weak layer has been identified around Mt. Hood. It would be prudent to assume it also exists in southern portions of the zone like Mt. Adams and Mount St. Helens. NWAC forecasters in the Crystal Mountain area did not find buried surface hoar during their tour Friday. No avalanches related to this layer were reported.

That said, it does exist in the snowpack in some areas and could begin to produce avalanches with additional loading. This layer might reach a tipping point as recent and future storms incrementally load this layer with a few inches at a time. 

While there has been a steady trickle of observations from the northern portion of West South, uncertainty remains about conditions on the southern volcanoes. The southern half of our zone may have been and continue to be the outlier, picking up more snow and and seeing locally higher avalanche hazard. If you are traveling in one of these areas check out the forecast for Hood, be prepared to make your own observations, and then let us know what you find.

Regioni coperte