Bollettino valanghe

Mount Shasta

Mount Shasta Avalanche Center
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Pericolo valanghe

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

In sintesi

You could trigger a wind slab avalanche above treeline where blowing snow is accumulating on north, northeast, and east aspects. With rain-on-snow up to 8,000 feet, you may find unstable wet snow below and near treeline on all aspects. Keep an eye out for cracking and hollow snow, manage exposure to terrain traps, and give cornices plenty of room.

Problemi valanghivi

  • Wind Slabs

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

    Powerful south to southwest wind and about six to 10 inches of new snow above 8,000 feet will make triggering a wind slab avalanche possible today. The wind will blow moderate amounts of snow onto leeward aspects above treeline over the next 24 hours. At 6,000 feet, speeds will be 10 to 20 MPH, while at 10,000 feet, the wind will howl at 35 to 45 MPH.

    You'll be most likely to find wind slabs on north, northeast, and east aspects. Though, you may find the wind has crossloaded snow into slabs along the sides of gullies on northwest or southeast facing aspects, as well. The leeward sides of trees and the along the sides of gullies are common terrain features that serve as catchment areas that may 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.

    (3/13/2025)

    A wind slab avalanche and cornice near a ridgeline

    Photo: Cory Beattie

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    While last night was cooler than the night prior, temperatures below and near the treeline were above or just barely freezing. The Castle Lake weather station recorded a low of 36° Fahrenheit and the weather station on Gray Butte recorded a low of 31° Fahrenheit.

    As rain and water from melt, works its way through the snowpack, it can exploit any weak layers and trigger an avalanche that starts small and then grows as it entrains more wet snow moving downslope. These avalanches can be small yet mighty, as they could carry you over hazardous terrain such as a section of cliffs or down into trees.

    If you observe roller balls or if you're sinking deep into wet snow when you step off your sled, skis, or board, this is a big indicator that wet loose instability is on the rise. Use care when traveling on steep slopes today, especially near hazardous terrain features.

    Wet-loose avalanches off Yellow Butte within the last 24 hours

    Photo: Eric Falconer

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Today is slightly cooler, but with temperatures still near or above freezing, additional loading from wind, snow, and rain, these cornices are still not to be trusted. Most cornices around the forecast area are on the north and east sides of ridges, but because of differences in terrain and how the wind moves through the mountains, you could find them on any aspect.

    Cornice fall can be tricky to predict as they often fail without notice. This time of year, especially during warming periods, is when they are most likely to fail. The best way to prevent being crushed by one of these burgeoning beasts is to avoid or limit your travels beneath them, staying much further back from the edge of ridges, and keeping bare earth or trees between you and the edge.

    (4/4/2025)

    Cornice fall in the Seven Lakes Basin

    Photo: Samuel Clairmont

Avalanche Discussion

Yesterday's field observations revealed small natural wet loose avalanche activity on a west aspect of Yellow Butte in the Old Ski Bowl.

If you're wondering why we only have a wet loose avalanche problem posted and not wet slab too, the reason being is that we don't have a significant and/or widespread layer of concern that would make a wet slab avalanche more likely. Regardless of if it's a wet loose or a wet slab avalanche problem, we manage them the same because they share the same weaknesses: warm weather and rain-on-snow. Even though the sun isn't out, with sustained warm temperatures and now rain-on-snow up to 8,000 feet, we may continue to observe wet avalanche activity below and near treeline. Watch out for changing conditions and limit your exposure to terrain traps.

The Everitt Memorial Highway and Castle Lake Road are currently closed to automobiles. The Siskiyou County Road Department currently lacks a functioning snow blower and is awaiting new equipment. Snow removal will begin as soon as possible.

Regioni coperte