Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

A rapid warmup is expected to destabilize the snowpack, resulting in dangerous conditions and natural avalanches on Thursday. Some avalanches could run on a crust 2-3ft deep and become large. Get a very early start, finish early, and plan your tour to avoid slopes well before they begin warming up.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Skyrocketing temperatures should destabilize the snowpack on Thursday. Natural avalanches may occur once the daytime begins to warm up. Slides may become large in larger terrain features. Choose terrain with plenty of options that allow you to easily avoid slopes steeper than 35 degrees, if necessary. Also, start and finish your tour early if you do go out.

    Wet avalanches should start on east aspects in the morning and follow the compass clockwise, around to south and then west aspects later in the day. Signs of warming are moist, sticky surfaces and moist snow falling out of the trees. Indicators that wet loose avalanches could occur include rollerballs and other wet avalanches. If you see or hear these, move to more shaded or northerly aspects or slopes less than 35 degrees. Plan your day to stay clear of runout zones and avoid overhead avalanche hazard from slopes once they begin to warm up.

    Wet loose avalanche activity after a sunny day post-storm.

    Photo: Matt Primomo

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    There's lots of wind-affected snow out there at upper elevation and exposed slopes. Slabs may become more cohesive and may fail more easily with warming temperatures and sun on Thursday. With such a rapid warmup and 2-3ft of dry snow over a crust, slabs may take on more of a wet slab characteristic later in the day. These could be in areas that were previously all dry wind slabs.

    It'll be best to avoid steep slopes once the snow begins to become wet and sticky on Thursday, whether they are wind textured or not. Stay out from under cornices and avoid walking on or near them. 

    (4/6/2022) Public Field Report: Austin Pass near Mt Baker Ski Area

Avalanche Discussion

On Wednesday, cold morning temperatures slowly warmed up and some small wet loose activity was noted on steep SE facing terrain near Jim Hill by around noon. Wind slabs appeared to be settling out in some areas, and cold dry powder skiing was found on shaded slopes. Snow surfaces warmed up and became sticky shortly after noon. The avalanche activity observed during the day was less than expected, as cool temps and easterly flow helped keep slides to a minimum. At least one deep avalanche was triggered near Mt Baker Ski Area on Wednesday however, and it ran down to the recent crust 3-5 ft deep. Thursday should be a very warm day, and overnight temperatures are expected to climb a few notches warmer than Wednesday morning. There's uncertainty about the likelihood for deeper slab avalanches, and the size of loose wet avalanches that may occur on Thursday. It is worth noting that it should quickly become a more dangerous day than Wednesday was. 

The recent storm dropped 2-3ft on Stevens Pass. Storm snow has generally been bonding well with the crust from early April in the zone, but some avalanches were triggered and ran on the crust on Tuesday. These were 3ft deep in wind loaded (SE facing) terrain. Josh and Irene traveled in the Stevens Pass side-country on Tuesday, and found fresh cornices and wind features were easy to trigger. The storm snow had gained strength, but strong over weak layering could still be found about 1.5 feet below the surface. If you're in the mountains, submit an observation and let us know what you see.

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