Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

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

Steer around steep terrain features you suspect hold slabs of recently wind-drifted snow.  There isn't much sun in the forecast, but near and above-freezing temperatures mean you can still encounter wet snow avalanches. Limit travel on or directly under steep slopes where the snow is wet and unsupportable.

Problemi valanghivi

  • Loose Wet

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

    Small wet avalanches will become easier to trigger in the afternoon as temperatures and snow levels rise. You can trigger avalanches on slopes where you find moist snow,  rollerballs, and natural wet avalanches. While wet slides are easy to predict, they can be forceful and push you into rocks and trees. Steer around steep convexities and move to lower-angle terrain to avoid triggering these slides.

    (1/29/2024)

    Lookout for small wet avalanches at low and mid-elevation terrain, especially as temperatures warm in the afternoon or during sun breaks. 

    Photo: Dallas Glass

  • Wind Slabs

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

    Stevens Pass isn't getting the bigger snowfall amounts seen in other forecast zones, but there is enough snow trickling in each day for alpine winds to keep drifting snow and forming small slabs. You are most likely to trigger a slab avalanche on the leeward sides of ridges at upper elevations, though you may find wind-drifted snow and wind slabs at mid-elevations as well. Blowing and drifting snow, shooting cracks, scoured snow surfaces, and stiffer feeling snow are all key observations to help you identify and avoid wind slabs.  

     

    Small wind loaded features at ridgeline can serve as test slopes to gauge the reactivity of fresh wind slabs.

Avalanche Discussion

Thursday should be a bit of a repeat with a few inches of new snow, cloudy skies most of the day, near-freezing temperatures, and alpine winds strong enough to move around some snow and form small slabs. On Wednesday, the Brooks precipitation gauge picked up 0.3" of water which equaled out to  3" of new snow at about 5000'. Winds were generally light and mid-elevations.

Stevens Pass Patrol reported 3-6" of snow on Tuesday, and they triggered both small wet avalanches and small pockets of wind-drifted slabs. On Sunday, observers reported shallow, wet loose avalanches up to size D1.5. Stevens Pass picked up 4-6" of snow, which was warm and moist on all aspects at middle and lower elevations.

Following an extended period of very warm temperatures in mid-March, the upper snowpack has gained strength and is still in the process of freezing. You can still find crowns, piles of debris, and frozen rollerballs on many steep slopes as a result of the March warm-up. On the 22nd, an NWAC forecaster on Skyline Ridge reported a supportable crust in open terrain. The crust was softer and more variable at the lowest elevations and in the trees. As the subsurface crust grows stronger, we have less concern about older, weak layers deep in the snowpack. At this point, an avalanche failing on or just above the early February crust would be very unlikely.

Regioni coperte