Bollettino valanghe

Mount Shasta

Mount Shasta Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
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

Today's repeat in weather will cause a rise in wet-loose snow instability near and above treeline. Heightened avalanche danger exists on steep, solar-lit slopes near rock outcroppings and cornices. Recent avalanches, pinwheels, and boot cuff snow penetration are evidence of unstable surfaces. Avoid being on steep solar aspects during peak warming and seek shadier terrain to reduce your risk.

Problemi valanghivi

  • Loose Wet

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

    It's been three full days of strong sunshine, above-freezing temperatures, and poor overnight refreezes. These combined factors have gradually caused snow surfaces to weaken and become more susceptible to avalanche. Today's continuation of warm weather will push solar-lit slopes to their threshold. Wet loose avalanches are possible on W-S-E aspects at all elevations, with particular emphasis on terrain near and above treeline. Steep east and south aspects will be the first and quickest to soften and lose surface cohesion. Areas near rock outcroppings should be considered with extra caution, as they expedite the heating of surrounding snow surfaces.    A single point release of snow has the potential to grow rapidly, travel long distances, and entrain larger amounts of snow. Wet loose avalanches hold a great deal of mass and weight, and can easily sweep an unsuspecting rider off their feet and into unforgiving terrain. Be cognizant of the terrain you are traveling through in relation to the time of day and surface conditions. A boot penetration that exceeds the boot cuff means there is enough unstable surface snow to cause an avalanche. The best way to manage wet loose avalanches is to travel when the snow surface is colder and stronger. Rollerballs and pinwheels are obvious precursors to wet loose avalanches.

    A wet loose avalanche that started at a single point and rapidly grew in size. Photo from last year at Castle Lake

    Photo: Eric Falconer

  • Cornices

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

    Cornices have taken up residency on many of the existing ridgelines near and above treeline throughout the advisory area. Many of these cornices are the size of small cars and have the potential to significantly injure or kill someone if they collapse. The best advice is to avoid being on, under, or near them, especially in the heat of the day and if the connecting terrain is experiencing warming. Overhung cornices notoriously break further back than expected and can catch people by surprise. The impact of a cornice collapse can also trigger an avalanche on the underlying slope.    

    Drooping overhung cornices experiencing warming

    Photo: Eric Falconer

Avalanche Discussion

No signs of wet loose avalanche activity have been observed — yet. Yesterday held a mix bag of conditions. Firm snow surfaces exist on westerly and northerly aspects and pose the threat of slide for life conditions in steep terrain. Variable softening surfaces exist on E-S-W aspects, predominantly near and below treeline, with some areas thawing mush faster than others. Yesterday, near treeline on a south aspect, boot penetrations ranged from 4 to 12 inches. Below treeline has not experienced a decent refreeze in 48 hours, and snow conditions are wet, heavy, and sticky. Tread cautiously, as it's easy to become injured in such conditions. 

Several summits have been achieved by climbers over the past few days. Reports all confirm that ski conditions above Helen Lake are heinous and surfaces are reluctant to warm, meaning self arrest skills are essential for both ascending and descending. Falling rime ice remains a threat to anyone climbing beneath rimed rock outcroppings. 

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

Regioni coperte