Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Triggering a 1-2 foot thick avalanche in wind-affected terrain remains possible. Avalanches failing on deeper weak layers are less likely but can't be ruled out in rocky, wind-affected terrain. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    What is it? Several weak layers are buried in the snowpack's upper 1-2 feet. On slopes that face away from the sun, you'll find some surface hoar and facets at these interfaces. On slopes that face the sun, you'll discover crusts with some small facets here. Further down in the snowpack, you'll find layers of weak snow near the ground. Triggering an avalanche on any of these layers is most likely in wind-affected terrain steeper than about 35 degrees.

    Where is it?  Expect to find at least one of these weak layers on most slopes in the mid and upper elevations. Most of them are more dangerous in areas with recent wind-affect. The surface hoar is most problematic in somewhat protected, middle-elevation terrain that faces NW-N-NE. Older weak layers (crusts and/or facets, occasionally surface hoar) can be found in rocky, wind-affected, alpine terrain where the snowpack is less than 3 feet thick (see Ethan's video at right/above).

    How can you recognize it? Wind-loaded slopes have harder surfaces and a distinct appearance of pillows or lens-shaped slabs of snow. Cracks shooting out from your machine or skis clearly indicate an unstable slab. Even small slabs that knock you off your feet and send you downslope can carry high consequences in the wrong terrain (photo here).

    How can you manage it? You can reduce your risk by avoiding very steep (greater than about 35 degrees), shady slopes (facing NW-N-NE) with hard or stiff wind-blown snow at the surface—especially those with ugly consequences if caught in an avalanche. Persistent slab avalanches may break wider than expected or higher on the slope above you. 

Avalanche Discussion

After a solid start to the season, snowfall in January largely missed this zone. Because of that, the snowpack has remained thinner here, and the weak layers we buried in November, December, and January are all still "in play." Slides on weak layers closer to the surface are more likely, but large avalanches failing on weak snow deeper in the snowpack can't be ruled out. You're most likely to get into trouble in places with stiff wind slabs and drifts resting on a weak, faceted snowpack in rocky, wind-affected, alpine terrain. Lots of terrain looks like this in the Pioneer, Boulder, and White Cloud Mountains, which make up most of this zone.

1-3 inches of snowfall and moderate winds are expected to arrive just before sunset. If the storm comes in earlier, look for active wind-loading. Pay attention to increasing wind transporting snow and creating fresh slabs over older ones. These slabs are likely small but can add stress to the weak layers mentioned in Avalanche Problem #1. 

Regioni coperte