Bollettino valanghe

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Warm spring-like weather means wet avalanche problems are our biggest concern. Last night barely hit freezing in upper elevations. As the day warms danger of wet loose slides on steep solar aspects will increase.

Problemi valanghivi

  • Loose Wet

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

    Spring like conditions have predominated the forecast zone over much of the past week. One good thing about this is that the warming has been slow and steady, with no major spikes in temperature and refreeze occurring nightly.

    Yesterday we found moisture had penetrated the upper snowpack on all aspects at all elevations. But we also found that surfaces were refreezing with a thin crust quickly after passing out of direct sunlight.

    Pinwheels and snow clumping to the bases of your skis or skins are a sure sign that the upper snowpack is moist and wet avalanches are a possibility. Danger of wet loose avalanches will be greatest on steep solar aspects during the hottest part of the day. Plan your tour carefully to avoid traveling on or below these slopes during the early afternoon.

    Pinwheel roller balls.

Avalanche Discussion

We soaked up some vitamin D in our short sleeves yesterday as we toured up Sunset and Goose Peaks.  Although we found a moist upper snowpack on all aspects, likely due to overnight cloud cover providing a thermal blanket, the ski conditions were variable (crusty to mashed potatoes) depending on aspect and time of day.

As stated above, the best part of this past week’s spring like temps, in terms of avalanche danger, has been that the warming has been slow and incremental, with no huge single day spikes, and with nightly refreezes. Generally speaking this should help break down persistent weak layers and increase stability. That said, we need to continue to be aware of persistent weak layers in the upper meter of snowpack, which are buried surface hoar and facets near the January freeze/thaw crusts. Watch them carefully to see how they react to warming. Rapid infusion of liquid water into these layers increases their reactivity. Don’t get complacent, look for these persistent weak layers and see how they are reacting before jumping into avalanchable terrain.

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