Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

You could still easily trigger large, dangerous avalanches in steep terrain. The most problematic areas are wind-drifted slopes below ridgelines and sheltered north-facing terrain. After a long January drought, the variable and weak snowpack is still adjusting to the recent snow. This uncertainty makes patience and conservative terrain choices on low-angle slopes essential. 

Problemi valanghivi

  • Storm Slabs

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

    You will likely find both storm and wind slabs of variable sensitivity throughout the terrain.  Avoid steep lee slopes below corniced ridgelines, the base of cliffs, and cross-loaded gullies where triggering an avalanche is most likely. Storm slab reactivity may be highly variable since recent snow fell on a myriad of old snow surfaces. Adjacent slopes may have significantly different stability. We believe the most likely place to trigger a storm slab is northerly terrain, particularly in open glades and meadows, where recent snow fell on weak, faceted snow and surface hoar. On other aspects, recent snow fell on slick crusts and stiff wind-affected surfaces.

    With an uneven distribution of old surfaces, quick handpit tests, kick turn tests, and test slopes you would normally use to assess stability might not be reliable. Consider this high level of uncertainty, give yourself greater safety margins, and enjoy the return to winter on low-angle sheltered terrain with limited overhead exposure. 

     Dry loose avalanches may run fast and far in the new snow as well. So know who is below and above you so you don't sluff out your backcountry partners. 

    (2/24/2021) An example of a widely propagating avalanche in new snow from a previous season. Rock Mtn. SE, 5,800ft.  Photo: Josh Hirshberg

Avalanche Discussion

Over the past 48 hours, between 1 and 2 feet of snow accumulated in the Stevens Pass zone, along with strong, gusty winds. We'll see continued winds through Sunday, accompanied by snow showers, and we'll likely pick up a few more inches of low-density snow. 

This recent snow fell on widely varying surfaces, and we are still working to gain information about the reactivity. Stevens Pass Ski Patrol and WSDOT avalanche forecasters reported mostly small storm slab avalanches, with a few larger wind slabs, releasing on the old surface or within the new storm snow. The new snow lacked cohesion due to the cold temperatures, and some backcountry users reported more dry loose avalanches than slabs. Another observer reported propagating extended column test results below the new storm snow. All in all, the results are mixed, and one day's worth of data isn't enough to know if these problems on the January Drought Layer (JDL) will persist. Compiling enough data to gain confidence about this problem will take some time, especially as the new snow settles and gets more cohesive. As we gain more information, we'll likely be able to narrow this possibility down. So, be patient as we gather info and wait for the weak snowpack to adjust to the welcome refresh of snow. 

You can help us build that data set by submitting an observation HERE or via the Avy App. 

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