Lawinenlagebericht

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
Keine Stufe
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The snowpack is currently shallow and the chance of triggering an avalanche is unlikely. However, instabilities such as buried surface hoar and a faceting rain crust are more intact on North aspects at mid and upper elevations. New snow accompanied by wind will increase the possibility of triggering an avalanche in wind loaded terrain this weekend.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    As the storm continues, new snow will build up and winds will increase. Winds coming from the W/SW will deposit snow on the N/NE side of ridges and form small wind slabs. This will become more of an issue moving into the weekend as snow totals are forecasted to increase. Be aware of a change in snow texture underfoot and cracking- these are tell-tale signs of instabilities and wind slab formation. 

  • Persistent Slabs

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

    Buried surface hoar can be found about 2 feet down below the surface on northern slopes at mid-upper elevations. This problem layer has showed variability in its ability to propagate and can be found fully intact in some locations and broken down in others. Rain from early December helped break up this layer, but did not fully wipe out this instability. Triggering an avalanche on the buried surface hoar remains unlikely, but if it is triggered could result in a larger avalanche due to the size of the slab sitting on top.

Avalanche Discussion

Observations around West Willow yesterday only proved how challenging it is to access good skiing at the moment. A mix of touring on bare earth dusted with snow, hiking, and a positive mindset will get you up to good skiing. Around 5,700ft the snow quality changes and deeper snow can be found. Up around 6,200ft the quality drastically improves and pockets of soft snow are asking to be skied. Pit observations revealed that the strength of the snowpack is good, and everything is sitting right side up. Structurally there are a few notable layers. First is a newly buried layer of surface hoar currently 1-3" below the surface. This formed 12/29 and has been buried intact by recent snow. Currently this isn't a big problem since there isn't much of a slab built on top of it. However, once new snow and winds move into the valley this is something to note and be aware of. You will find this new weak layer on less sun affected aspects, and will be most prominent on north-east facing slopes. Moving on down the snowpack you will find a rain crust that developed on December 22nd. We haven't seen this crust propagate, but we have been watching small facets form above and below it. Finally, we have our buried surface hoar from 11/24. This layer continues to be an anomaly as it has survived drastic weather changes and rain events. Despite all of that, we've seen a mixed bag of test results and occasionally will propagate. Large surface hoar feathers can be found preserved, and although you are unlikely to trigger and avalanche here, this will remain as a problem type until we have confidence that new snow won't stress out and reactivate this weak layer

Winter has made her return again, and we have already received a few inches of fresh snow. A small pulse of snow will fall today, and then snow increases on Saturday, with Monday and Tuesday being the heart of the storm. As the storm intensifies, so do winds. Expect the danger to rise as winds pick up early next week. 

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