Bulletin d’avalanche

Stevens Pass

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

A warming storm will bring the Stevens Pass area a welcome dose of precipitation. It's not much, but it might be just enough to form shallow slabs of wind-drifted snow, and warming temperatures may initiate small wet avalanches. Consider steering around steep slopes where you find textured drifts or wet heavy snow. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    Moderate winds could easily drift snow into shallow wind slabs. Actively blowing snow or a dappled texture to the snow surface are good ways to identify areas of wind drifting. Wind slabs may form over slick or weak surfaces, particularly at upper elevations. We're likely only going to receive 5-7" of snow, so in most terrain, these avalanches wouldn't pose much of a hazard. But in very steep, confined, or cliffy terrain, a small avalanche could cause a dangerous fall. Use extra caution and consider steering around more aggressive terrain features. 

    (1/18/2025)

    An example of shallow wind slabs, like the ones you may find on Thursday. 

    Photo: Joe Dellaporta

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    As temperatures climb on Thursday, we'll likely see a transition to rain at mid elevations. There won't be much fresh snow to slide, but in very steep terrain, we may see small, wet loose avalanches. More likely, we'll just see widespread rollerballs. Still, take the warming into consideration if you're in very steep terrain where wet, heavy snow could push you off your feet, over cliffs, or into trees and rocks. 

    (12/28/2024)

    Steep road banks are a great to observe wet snow instabilities, like these rollerballs and mini wet loose avalanches. 

    Photo: Katie Warren

Avalanche Discussion

Wednesday's snow totals were modest, with the Stevens Pass area picking up 2-4" of snow. Thankfully, it stayed as snow at pass level throughout the day. We'll see a bit more accumulation overnight and into Thursday, but it's still not a powerful storm by most standards. Unfortunately, we won't escape the warmth for another day, and we expect rain into our middle elevation band by the afternoon.

After the long dry spell, snowpack surfaces and structure have deviated significantly by aspect. Most surfaces have some form of melt-freeze crust. On southern slopes, the crust is thick and supportable, while it trends thinner and unsupportable on northern aspects.  Weak faceted snow has also been documented below these crusts on most aspects. At lower elevations and in shady, sheltered terrain, surface hoar and faceted grains may exist on the snow surface in isolated areas. There is uncertainty about whether it will bond well to these old surfaces. At elevations where this storm brings us snow and not rain, you should use quick hand pits and test slopes to assess the new/old snow interface. If the snow slides easily as a cohesive slab, avalanches will likely be easier to trigger as additional snow accumulates. 

Snow depths have decreased significantly due to prolonged warm temperatures and sunshine, particularly on sunny slopes, where patches of bare ground are not uncommon.  You can expect deeper coverage on the north half of the compass. Under the tree canopy, you can expect the most bumpy, variable conditions. Icy chunks and rough surfaces will be more akin to a frozen coral reef. Below 5,000ft, there are plenty of open holes, creeks, and exposed rocks on all aspects. While the warm snow and rain may soften the hard surfaces, don't forget about these shallowly buried obstacles.

Régions couvertes