Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Windy conditions should start to move the recent snow and form fresh shallow slabs in exposed areas. Watch for blowing snow to figure out local wind patterns and anticipate loaded aspects.

Problemi valanghivi

  • Wind Slabs

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

    There’s not a lot of snow available for transport, but there’s enough. As wind speeds increase, a fresh batch of wind slabs should start to grow. Since the wind will primarily come from the E-SE, they could load some strange aspects and unusual features. 

    As an active loading event, there should be plenty of clues to help you figure out which slopes are loaded. Blowing snow, sharp drifts, scoured slopes, and textured surfaces can help you determined features where these new wind slabs may exist. 

    While these slabs should be small, they will continue to grow throughout the day. With so many obstacles to hit, even a tiny avalanche could carry you for a very rough ride.

    (2/18/2023)

    Example: Signs of wind loading.

    Photo: Dallas Glass

Avalanche Discussion

The harder and longer the wind blows, the bigger and more widespread wind slabs will become. As a result, expect the avalanche hazard to slowly increase throughout the day. This could include isolated avalanches occurring at slightly lower elevations.

Eventually, snow should start to fall. Sadly this isn’t a very big storm, and the Pass should only see an inch or so by the end of Tuesday. It will, however, add to the snow available to blow around in the moderate to strong winds.  On Monday, observations reported surface hoar in sheltered areas. This is in line with adjacent zones where surface hoar, near surface facets, and firm crusts were observed. These weaker grains, shouldn’t play much of a role but could make some wind slabs very easy to trigger. 

On Saturday, a storm brought a few inches of fresh snow. It was only a dusting at Pass level, but higher in the terrain, 4in or more accumulated. This recent snow fell over a new crust (12/30), which observers reported as supportable at middle elevations and becoming breakable lower. The primary layer we’re tracking in the upper snowpack continues to be the 12/22 facet/crust matrix. This potential weaklayer can be found about 8-12in below the surface (see photos). 

Two notable avalanches occurred this week. On New Year’s Day, a skier was caught and carried by a very small isolated wind slab on the N side of Chair Peak (see photo). Also on the N side of Chair Peak, an avalanche professional reported a wet slab avalanche on Saturday, about 100ft wide and 8-12in deep (pic). 

Often, the biggest concern continues to be travel conditions. Variable surfaces and numerous obstacles can make travel much more “adventurous” than normal, especially at lower elevations.

Regioni coperte