Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

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

You could easily trigger avalanches in stiff, freshly wind-drifted slabs of snow on steep terrain below ridgelines. Watch for cracking in drifted snow as a sign to steer around steep slopes. Avalanches will likely be small, but in the wrong terrain, they could still push you into or through rocks, trees, or cliffs. 

Problemi valanghivi

  • Wind Slabs

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

    Stevens Pass should pick up 4-5 inches of snow, and moderate winds could form shallow drifts at upper elevations. The most likely places for wind slabs are steep lee slopes below ridgelines, and you can use cornice formations and textured surfaces to identify wind-loaded slopes.  If wind slabs form over slick crusts and weak surfaces, avalanches could be easy to trigger.  A great tool for assessing freshly formed wind slabs is to use small test features to assess how the snow reacts. Cracking or small slabs indicate unstable wind slabs. While we expect wind slabs to be small, they could still carry high consequences in steep, rocky, or confined terrain. 

    There isn't quite enough snow for a widespread storm slab problem in sheltered terrain. But with weak snow surfaces, very small, isolated avalanches could also occur on Saturday in sheltered slopes. While they aren't much of a hazard on their own, they could be a good indication of future problems as we, hopefully, get more snow. 

    (12/15/2024)

    A shooting crack in a small wind loaded slope. These small features give great feedback on how larger slopes may react. 

    Photo: Ryan Minton

Avalanche Discussion

Stevens Pass isn't favored in this storm pattern, but it will be a nice refresh for surfaces and just enough to start thinking about avalanches again. The bulk of the precipitation and wind should occur overnight, so Saturday should be a quiet weather day in the mountains with tapering precipitation and decreasing winds. There is even potential for short afternoon sun breaks. 

Observers have reported surface hoar and possibly faceted snow on surfaces as of the 12th. A series of sandwiched crusts exists on most slopes and also holds weak snow. These surfaces and upper snowpack layers will be buried on Friday night and could become problematic for future avalanches with enough new snow and load. After this first storm, it will be useful to use small hand pits to check the new interface. Take note and send us an observation if you see buried surface hoar or if the overlying snow doesn't seem well bonded. 

On Tuesday, an NWAC forecaster reported a couple of very small wet avalanches on Rock Mtn (6,400ft, SE). In Tunnel Creek at 5,500ft, SW, they found 3-4" of recent snow, punctuated by a thin crust. By now, those slopes will likely have another surface crust. At low elevations, you may find thick and breakable crusts on or just under the surface. Over the weekend, forecasters found that travel hazards outweighed avalanche hazards. Open creeks, bare ground, breakable crusts, and frozen chunder in forested areas are all things you might have to contend with to get into the more pleasant conditions above about 5500ft. 

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