Bollettino valanghe

Mount Shasta

Mount Shasta Avalanche Center
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Pericolo valanghe

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

In sintesi

Heightened avalanche conditions exist on upper mountain terrain, where continued warming will destabilize the snowpack. Wet loose avalanches and cornice collapse will be possible on W-S-E aspects at all elevations. Reduce exposure to these problems by getting off solar slopes before significant warming occurs. Watch out for pinwheels, small wet avalanches, and knee-deep boot penetration as signs of significant warming.

Problemi valanghivi

  • Cornices

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

    Throughout the course of the winter, large cornices have developed across the forecast area. As temperatures continue to climb, with poor refreezes overnight, these cornices will begin to weaken. If they fail, these cornices also have the potential to trigger a subsequent wet loose avalanche below. Some of these cornices are the size of small cars, certainly capable of hurting or killing someone if they fail. Best bet is to stay off of them over the next 24 hours. Give these cornices a wide berth, as they notoriously pull back further than expected.

    (3/25/2023)

    An older photo of large cornices at Cliff Lake. March 2023.

    Photo: Samuel Clairmont

  • Loose Wet

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

    Calm winds, sunny skies, and warm temperatures will continue today. Last night provided a very poor refreeze of the upper mountain, with some areas not freezing at all. This is the first time above treeline terrain has not had an effective refreeze overnight through this cycle. Upper mountain terrain will start the day off warm, quickly destabilizing as the warm temperatures penetrate deeper into the snowpack. Wet loose avalanches are possible on W-S-E aspects at all elevations, with particular emphasis on terrain near and above treeline. These slides have potential to become large, capable of burying you, or carrying you over consequential terrain. Look for early signs of rising instability such as roller balls, pinwheels, sticky snow, failing test slopes, and deep boot penetration.

    (12/30/2023)

    D1 wet loose avalanche. An obvious sign of rising instability.

    Photo: Samuel Clairmont

Avalanche Discussion

Today will be a continuation of the warming trend, pushing the temperatures a tad higher. The significant change to note is last night's upper elevation temperatures. Gray Butte, is recording 36 degrees F as of 5am, meaning terrain at 8,000 feet (and above) did not effectively freeze last night. Once the sun hits the slopes this morning, surface snow will begin to soften and saturate. If you're planning to get out today, plan to get off solar aspects before the slopes warm to an unstable level, which won't take long. If you time it right, there is some good early season corn skiing to be had. Shaded aspects are seeing significantly less warming, and could remain quite firm at high elevations. 

Yesterday's observations are from the Gray Butte area. Forecasters found southerly slopes saturating quickly, with the top 4–6 inches of snow becoming soft and sticky. On the summit, the wind compressed surface snow stayed quite firm and unaffected by the sun. Northerly aspects stayed firm and wind affected. No avalanche activity was observed.

Climbers: In addition to cornice collapse and wet loose avalanches, watch out for significant rock/ice fall from the upper mountain. Most cliff bands (i.e. Shastarama, Red Banks, Casaval Ridge, Trinity Chutes) are covered in thick rime ice that has begun to shed with the warming conditions. This will happen quickly today. If you're going to be around those areas, wear a helmet, keep your eye out for smaller chunks before it gets worse, and don't spend time hanging out below them.

The road to Castle Lake is closed. Siskiyou County is working to get it open as soon as possible.

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