Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

You can trigger small slab avalanches where the wind forms fresh drifts of snow just below ridges. If you find moist or sticky snow at low elevations, you may be able to trigger small wet avalanches. Choose lower-angle terrain where you identify wind-drifted snow.

Problemi valanghivi

  • Loose Wet

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

    If you see rollerballs or moist, sticky snow that slides easily, stick to slopes under 35 degrees. Wet avalanches will be small an predictable, but they could be forcefull enough to push you into hazardous features like rocks or trees. The incoming precipitation will be moist snow or rain below 4,500ft, and will fall on up to 5" of dry snow sitting on a crust.

    (3/21/2023)

     An example of a wet avalanche from a previous season. Skyline area, S, 4600ft

    Photo: Matt Primomo

  • Wind Slabs

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

    If you find drifts up to 6" deep or cracks that shoot through the snow, steer around drifted areas. If you're uncertain, stick to slopes less than 35 degrees or choose wind-sheltered terrain. Blowing and drifting snow should show you which steep slopes are loading up with snow. Track the snow depth over a stout crust to find deeper drifts. Pay attention to differences in snow stiffness as you gain elevation and change aspects to help pinpoint where fresh wind slabs are building. 

    Up to 4" of snow will fall with southwest winds increasing by Sunday afternoon. Before snow begins, the snow depth over the early February crust ranged from 4” at the lowest elevations to 10” or more up high.

    (11/21/2023)

    Snow drifting onto leeward slopes is the observation that should definitely make you say, "That is a place where there could be a fresh wind slab."

    Photo: Matt Primomo

Avalanche Discussion

Heavy rain two weeks ago wetted out the upper and middle snowpack well into upper-elevation terrain. Low elevations lost significant snow height. Now that the water has drained and the wet snow is hardening up, a stout crust buried in early February is a new baseline from which to measure snow depth.

Recent snowfall has generally come down with much less wind than usual.  Periods of clear sky and cool temperatures have enabled some faceting. In some places, faceted layers - and possibly some surface hoar - have in turn been capped by more snow. The current upper snowpack structure isn't alarming, but it is worth monotoring. The dry snow on the early February crust could be a weak layer of the future.

If you make it out, please share what you found with an observation.

Regioni coperte