Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Saturday will be a wild and stormy day. Snow, rain, and strong winds will make it easy to trigger large avalanches, especially at higher elevations close to the Cascade Crest. Avalanche danger will increase rapidly throughout the day. Avoid steep slopes and choose conservative terrain.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–2

    Freezing levels are expected to rise to 5000ft. The warming temperatures and precipitation will create upside-down storm snow with heavy, dense snow on top of lighter, softer snow. This heavier snow will slide easily on the lighter snow beneath, and it will be possible to trigger avalanches that are big enough to bury or kill you. Slabs will form on all aspects and elevations with consistent snow. Consider traveling on low-angle slopes and think through the increased consequences of being caught in an avalanche in areas with low snow coverage. 

    Strong winds will build deeper drifts of snow on lee aspects, avoid traveling near ridgeline or in open terrain that is wind affected. 

    Saturday will be a good day to look for bullseye data to inform you that the snowpack is unstable and avalanches are likely. Look for recent avalanches, blowing snow, or shooting cracks. Any of these signs are an indication that you should stick to low-angle slopes. 

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    With freezing levels increasing and snow turning to rain below 5000ft, expect small wet loose avalanches in areas near and below treeline. A wet snow surface, rollerballs, and rain on dry snow are signs of a wet loose avalanche problem. Also, avoid traveling below steep terrain where avalanches may begin and entrain additional snow while moving downhill. 

    Example: Rollerballs like these are a good indication that wet loose avalanches are likely.

     

    Photo: Andrew Kiefer

Avalanche Discussion

Tomorrow will likely bring a mixed bag of stormy weather, including snow, rain, freezing rain, and strong winds. With this storm impacting our mountains, avalanche danger will increase rapidly. Warming temperatures, especially when snow changes over to rain, will increase the likelihood of triggering storm slabs and wet loose avalanches in the new snow. At upper elevations, strong winds will be blowing snow around and quickly building unstable wind slabs. With winds up to 40-50mph, deep slabs can be created on all aspects and sometimes in places further down from ridges than expected. If you brave the stormy conditions tomorrow, stick to wind-sheltered terrain. 

While some areas of the East South zone still lack enough snow to produce avalanches, other areas have a significant and layered snowpack. We have little information and a lot of uncertainty about snowpack conditions near and above treeline. There is a lot of variability from north to south and east to west throughout the zone, and a more substantial snowpack exists in the northern and western portions. Expect that avalanche danger will vary, with increased danger in places close to the crest with a deeper snowpack. 

While we're excited about issuing daily forecasts for the East South zone this season, we need your help in making this successful. However and whenever you recreate in the mountains this winter, send us your observations.  - The team at NWAC    

 

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