Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Sat
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Continued snowfall will maintain dangerous avalanche conditions Friday. Give the snowpack time to adjust to the added load of new snow and steer around open slopes greater than 35 degrees. Expect larger and more dangerous avalanches at upper elevations and in areas of wind drifted snow.

Problèmes avalancheux

  • Storm Slabs

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

    New snow Friday (2-5in Crystal, 6-10in Paradise) will bring storm totals over the past week up to 2-3ft. Expect a warming trend with snow levels rising from 3000ft to 4000ft by the afternoon. Natural and human-triggered avalanches within recent storm snow could grow large. Avalanches may be easiest to trigger during periods of heavy snow or warming temperatures. You will likely encounter thicker and more reactive slabs in wind affected terrain at higher elevations (Observation). Simple uptrack tests and hand pits may easily highlight storm snow layers of concern. Continue to make assessments throughout the day. Conditions can change rapidly during storms like this.

    We’ve been talking all week about buried surface hoar and facets in the West-South zone. So far, we have not received reports of any avalanches on this layer. However, NWAC forecasters continue to find these weak grains in the snowpack. You’re most likely to find buried surface hoar or facets near treeline about 4” (10cm) above the very prominent 12/09 crust. If you see shooting cracks or feel collapses, seek out low angled terrain well away from steep slopes.

    (12/16/2020) Skin track test showing cracking in the surface snow. This can indicate storm slabs are present.

Avalanche Discussion

This long-running active weather pattern favored the volcanoes where you will find the most snow and the most dangerous avalanche conditions. Other areas throughout the zone may experience locally lower avalanche hazard. Expect any avalanche activity to involve recent snow above the 12/09 crust layer. Use this layer as a marker in the snowpack and carefully assess the recent storm snow above. 

At the lowest elevations, a mix of rain and snow could produce small loose wet avalanches by the afternoon. The snowpack on these lower slopes has been through a lot over the past few weeks with warm temperatures and several rounds of rain. This should limit any avalanche activity. Early season conditions continue to weigh on our minds. At lower elevations and on exposed ridges, expect thin coverage and shallowly buried obstacles. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Régions couvertes