Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Tue
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

New snow accompanied by warming temperatures will build unstable slabs on Sunday night and Monday. You may easily trigger large avalanches in the new snow. Avoid steep terrain in areas near and above treeline.

Problèmes avalancheux

  • Storm Slabs

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

    Moderate precipitation will impact the southern Washington Cascades overnight on Sunday and throughout the day on Monday. This storm may bring up to 1ft of snow with increasing temperatures. The warming trend may very well build an upside snowpack with heavier, denser snow on top of softer, lighter snow. The heavier snow will likely slide easily on the lighter snow beneath. Avoid steep terrain in areas near and above treeline. Below treeline, make observations as you travel, look for recent avalanches, shooting cracks and collapses, and use small test slopes to see how well the storm snow bonds to the underlying surface. Choose conservative terrain to avoid the high consequences of being caught in small avalanches where you could be carried over and into many obstacles.

    Areas in the southern portion of the zone are forecasted to get the most snow, with snow totals tapering off towards the north. This pattern will likely create elevated danger in the south and lower danger in the north. 

    Test slopes can give you a lot of good information about how new snow is reacting during a storm. This test slope shows that storm slabs are sensitive and propagating easily.

    Photo: Charlotte Guard

Avalanche Discussion

The southern Cascades experienced a brief lull in the storm yesterday, with cooler temperatures, light winds, and 3-4 inches of snow accumulation. Another round of snow is forecasted to impact the southern Cascades on Sunday night and Monday. Warming temperatures will likely create unstable new storm snow. There is a potential for snow to change over to rain in the evening hours on Monday. If this occurs, wet loose avalanches will quickly become a concern. 

Rain from December 18th may have created a melt-freeze crust on the existing snow surface below 4000ft in many locations. At higher elevations, heavy, moist snow is overlaying colder snow from the previous week. Smaller avalanches in the new snow may step down to these interfaces from Saturday’s storm.

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, throughout the zone. 

Régions couvertes