Bollettino valanghe

Silver Valley & Bitterroot Mountains

Idaho Panhandle 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 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wind and a few inches of new snow are combining to build new wind slabs that will become possible to trigger. These new, unstable slabs will increase in size and likelihood of triggering today and tonight but should remain small during daylight hours. You can avoid this avalanche problem by sticking to wind sheltered terrain and staying off wind loaded slopes steeper than 35 degrees, which you’re most likely to find on the northern half of the compass rose today.

Problemi valanghivi

  • Wind Slabs

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

    New and generally small wind slabs forming near and above treeline today should become increasingly likely for you to trigger. Light to moderate South and Southwest winds yesterday continue with a slight increase today as approximately 3” of new snow falls. These wind speeds are building reactive and relatively soft wind slabs in lee terrain from both the new snow and some existing snow on the ground. Signs of active wind transport and deposition, as well as cracking under your weight, can help you identify this avalanche problem. If you’re out after dark, realize that continued new snow and wind may increase the size of these new wind slabs.

    Older wind slabs formed since the 1/7-1/8 storm have gained some stability but are still worth keeping in the back of your mind. These large wind slabs are generally present in the same terrain as today’s new wind slabs. While stubborn or even unreactive to a human trigger, there is some potential for a smaller avalanche in newer slabs to entrain or step down to these larger older slabs.

Avalanche Discussion

Beneath the wind slabs forming today, the older storm slabs and wind slabs from our 1/7-1/8 storm are gaining stability but continue to be worthy of your consideration and assessment when choosing terrain. In field time on Monday in the upper Canyon Creek drainage and the north ridge of Burke Summit we found minimal to no cracking under our skis. Compression tests produced results on two distinct storm layers which did not propagate in extended column tests. We expect significant spatial variability in these storm layers in our above treeline terrain that has been heavily wind affected. Below the 1/7-1/8 storm snow, we continue to find good stability.

Well-developed surface hoar has been observed in many open, wind sheltered areas below and near treeline. Our cold, clear weather with some temperature inversion Saturday and Sunday nights was ideal for creating surface hoar. Snow today and tonight may bury this surface hoar intact, but rising snow levels may allow rain to melt this potential persistent weak layer before it’s buried intact. Snow levels are forecast to rise towards by 7,000’ by early Wednesday. Watch for rain wetting the upper snowpack and potentially creating loose wet and wet slab avalanche problems Wednesday.

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