Lawinenlagebericht

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

An Avalanche warning is in effect. Winter is back with a vengeance after we have had a snow drought for so long!  The 30 cm from earlier this week buried a widespread surface hoar layer.  Yesterday and last night we received another 25 to 30 cm (~10 inches +) and it is still snowing. Snowpacks don't adjust to rapid change well, and this is a lot of loading on an already reactive weak layer. Very dangerous avalanche conditions exist. Travel in avalanche terrain not recommended. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    The winds have been moderate to strong out of the West - Southwest, but they shifted to North in the night meaning that there is a possibility of finding wind slabs on every aspect. The light density snow will be easily pushed around to form wind slabs. Look for chalky, hollow sounding snow that is pillow like. Expect them on aspects you might not normally find them.  The ones on the Northern aspects could be blanketed by a layer of snow since the winds shifted in the night during the storm.  

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1–3

    When the snow last week started, it came in soft and no winds, burying a well-developed surface hoar layer across the entire forecast zone and at all elevations. The storm earlier in the week left us with about 30 cm on top of that surface hoar.  Yesterday, everywhere we travelled we were getting shooting cracks and collapsing on that layer.  When we were in wide spaced trees, the cracks were shooting from tree to tree, going across a large area at once.  Last night's additional snow of upwards of 30 more centimeters in locations is a lot of change rapidly. Expect to see natural avalanches on this layer today and human-triggered avalanches are likely.  

    (2/4/2021) Remote trigger on buried surface hoar. This was triggered yesterday on the opposite side of the ridge, from back in the trees.

Avalanche Discussion

Yesterday we travelled up Burke to Glidden Ridge. When we were on our skis and off the snowmobile trail; we heard, felt and saw collapsing and cracking in the snowpack on every aspect.  This didn't matter whether we were in wide spaced trees or in the opening.  We could get the snow to easily slide on small, steep terrain features and at one point remotely triggered an avalanche from the opposite aspect.  Reports from others across the zone are the same about the buried surface hoar layer.  This problem has the chance to stick around for a while.  Expect the danger to be elevated through the weekend as we continue to receive more snow and winds. 

 

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