Bollettino valanghe

Mount Shasta

Mount Shasta Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Continued southerly wind and snowfall will increase the likelihood of avalanches on all aspects and elevations. You could trigger an avalanche large enough to bury you on steep slopes in areas protected from or exposed to the wind. Increase your margin of safety by choosing low angle terrain and watching for signs of unstable snow like cracking and collapsing.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Powerful south to southwest wind, continued snowfall, and one to two feet of new snow will make triggering a wind slab avalanche likely today. The wind will blow large amounts of snow onto leeward aspects near and above treeline over the next 24 hours. At 6,000 feet, speeds will be moderate blowing 10 to 20 MPH, while at 10,000 feet, the wind will blow 20 to 30 MPH.

    You'll be most likely to find these wind slabs near and above treeline on north, northeast, and east aspects. Though, you may find the wind has crossloaded snow into slabs along the sides of gullies on west, northwest, or southeast facing aspects, as well. The leeward sides of trees and other terrain features are common catchment areas that can harbor deep accumulations of wind transported snow.

    An avalanche today could be several feet deep and may not be survivable. Use caution if traveling on any of the shaded aspects of the compass rose steeper than 30°. Look for drifting, shooting cracks, and collapsing. Listen for hollow, drum-like surfaces and feel for density changes from soft to firm or shallow to deep.

    Wind slab below a ridge on the west side of the forecast area.

    Photo: Nick Meyers

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    With heavy snowfall below and near treeline, the potential for finding a storm slab is on the rise. Storm slabs form in areas protected from the wind and will be softer than the wind slabs you're likely to find on leeward aspects near and above treeline. This problem is of greatest concern during, and immediately following, substantial winter storms. They can often catch folks off guard because it's a problem most commonly found in and near trees where a false sense of security can develop; if the trees are wide enough for you to ride through, then they're wide enough for snow to slide through. 

    As the snowpack adjusts to one to two feet of new snow, be on the lookout for shooting cracks and collapsing, dig down and investigate the stability of recently accumulated snow before committing to steep terrain.

    In steep terrain where the snow has yet to settle into a slab, you may trigger a dry loose avalanche. These avalanches are typically small but fast moving and could carry you into a terrain trap. Keep an eye over your shoulder for sluff build-up and move out of its way before it gathers enough steam to sweep you off your feet.

    Small dry loose avalanche initiated by skis

    Photo: Eric Falconer

Avalanche Discussion

Recent observations:

Gray Butte. We observed about 15 centimeters of new snow resting on a thin, and brittle melt-freeze crust from 3/29. This layer fractured with moderate loading steps but did not propagate during extended column tests. South to southwest wind was blowing large amounts of snow onto northerly aspects. 

Old Ski Bowl. Before the current storm system, we found generally stable avalanche conditions. Frozen snow surfaces extended up to 8,000 feet in the morning, and by the afternoon, snow softened, improving riding conditions below treeline. Above treeline we found minimal wind effect and a right-side-up snowpack.

Regioni coperte