Bulletin d’avalanche

West 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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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

If you venture into the mountains on Saturday, expect to be battling a potent winter storm and dangerous avalanche conditions. Red flag signs of instability such as recent avalanches, whumpfing collapses, or shooting cracks should steer you away from slopes over 35 degrees. Choose conservative terrain and realize that early season conditions still exist.

Problèmes avalancheux

  • Storm Slabs

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

    Look for Storm Slabs to develop on Saturday at all elevation bands as the West South is targeted by a potent winter storm. These slabs will be thicker and more reactive as you ascend in elevation or in wind-loaded terrain, particularly on the volcanoes where more impressive water numbers are expected. Multiple storm layers and density changes are expected to exist above the Late November Crust, so use test slopes and hand pits as you travel to look for layers of concern. If you find heavy snow over light snow, see recent avalanches, or notice shooting cracks or blocks of snow failing in your tests, avoid slopes over 35 degrees.

    (12/10/2021)

    The Late November Crust should be a prominent snowpack marker for you to reference when you are looking for potential layers of concern. 

    Photo: Dallas Glass

Avalanche Discussion

Snow depths have slowly increased since 12/8 around the West South, and Saturday should be the biggest dump of snow the zone has seen this season. The depth of the snowpack could double in some locations by the end of the day on Saturday, greatly expanding the amount of terrain where avalanches can occur. At Paradise, a whopping 3” of precipitation is forecast to fall by Saturday evening, which could produce more dangerous avalanche conditions than areas closer to the crest (where we are expecting ~1.75” of water). Regardless of location or elevation, new snow will thicken the depth atop a firm base we are calling the Late November Crust. Any layers of concern will exist above this easily identifiable layer going forward.

Keep in mind that despite the new snow, early season conditions still exist. Open creeks, rocks, stumps, and other natural hazards that may have been visible on Friday could be just buried under the surface on Saturday. Take it slow and ease into winter, we are just getting started.

"Uphill travel reminder: Check in with your local ski area this weekend regarding terrain access and parking updates. Closed ski areas often share a similar snowpack and avalanche hazard as the surrounding backcountry. You may also encounter other hazards like active avalanche mitigation, unmarked obstacles, snowmobiles, groomers, and other heavy equipment as ski areas prepare to open. Be prepared to make your own assessments and handle emergency situations.”

Régions couvertes