Lawinenlagebericht

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Our avalanche main problems today are storm and wind slabs from yesterday’s storm. At upper elevations, six inches of new heavy snow fell on the thin covering of light snow from earlier in the week. Moderate to strong winds at upper and mid elevations yesterday transported new snow onto the lee side of ridges and terrain features, creating the potential for dangerous wind slabs. You can avoid this problem by seeking out sheltered terrain that has not been wind loaded.

At low elevations, the wintery mix of snow and rain has increased likelihood of loose wet slides.

Lawinenprobleme

  • Wind Slabs

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

    5 to 10mph winds from the south, and 25mph gusts, moved a lot of snow yesterday and last night. Our skin track completely filled in and disappeared yesterday during the hour we spent in our test pit. This problem will be most pronounced at upper elevations, but there may be wind loaded terrain at mid elevations as well. Be on the lookout for potential start zones in steep terrain that collects wind driven snow. Slabs will feel denser than surrounding snow and may have a pillowed, chalky appearance. Heed the tell-tale sign of shooting cracks.

  • Loose Wet

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

    Lower elevations received a heavy soupy mess of snow/rain mix, with lots of liquid to lubricate the snowpack. With the warm temps and melting we have experienced over the past week much of what has had the potential to slide has already moved. However, the new precipitation and lack of freezing temperatures at low elevations has added a load and increased likelihood of loose wet avalanches.

    Loose wet avalanches are very dangerous and difficult to escape as they may sweep a skier or rider into a terrain trap, and they set up like concrete. Hedge your bets and be very careful around steep slopes above terrain traps like gullies and cliffs if the surface snow is moist or wet.

Avalanche Discussion

Yesterday, we sledded up to Dominion Peak yesterday from the Taft parking lot. At upper elevations conditions were surprisingly good.

We found reactivity in multiple thin storm/wind slabs in the upper 20cm of the snowpack during our Compression Tests, but found no propagating reactivity in our Extended Column Tests.

Interestingly, in our North aspect test pit we found a layer of buried surface hoar 45cm below the surface that we did not expect to find. It appears that this layer was at least partially knocked down before it was buried because it had a strong bond to surrounding layers, however in more sheltered areas the buried surface hoar layer may be better preserved. This is a good reminder that avalanche hazards are spatially variable and can lay dormant. Small slab avalanches, such as our problem today, could step down to buried layers to create large inescapable slides.

Looking ahead, avalanche danger should trend down with calm and mild weather as we progress through the weekend.

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