Lawinenlagebericht

Bitterroot

West Central Montana Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

 Precipitation has subsided, and a solid refreeze last night has locked the snowpack in place. Expect a melt-freeze crust and mostly supportable snow conditions on all aspects at elevations below 8,000 feet. Watch for changing conditions as you travel to higher elevations. In the Southern Bitterroot, it may be possible to trigger an avalanche on buried facets on north aspects above the rain line. Choose terrain less than 35 degrees in slope angle and avoid high consequence runouts to manage this problem.  

Lawinenprobleme

  • Wind Slabs

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

    Light snow showers accumulated 1 to 3 inches of transportable snow since Thursday (3/3) evening. Light winds with moderate gusts, out of the northeast,  could form fresh drifts over hard rain crusts or various snow surfaces at upper elevations. 

    Use small safe, representative slopes to look for shooting cracks. Avoid slopes steeper than 35 degrees with wind drifted snow, especially where terrain traps such as steep gullies or cliff bands. 

    (1/26/2022) Example of a wind loaded pillow. Photo: Jeff Carty

  • Persistent Slabs

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

    In the Southern Bitterroot, buried facets have been identified two feet deep (62 cm) and show reactivity in snow pits on north aspects above approximately 8,000 feet. It may be possible to trigger a sizable avalanche on this layer in the isolated areas it exists- north-facing terrain above the rain line in the Southern Bitterroot. We recommend sticking to slope angles under 35 degrees in this area.

Avalanche Discussion

After an exciting rainy week, cooler temperatures and mild weather have entered the forecast area. Precipitation subsided over the past few days, and cooling temperatures have locked the snowpack in place. Light snow showers brought 1 to 3 inches over the past 36 hours. This fell over refrozen rain crusts in most areas.  

Winds have switched to north and easterly as the cooler temperatures pushed in. Overnight wind speeds have remained light with moderate gusts out of the east.

We found rain crust dominating snow surfaces up to 8,400 feet yesterday at the Gash Knob. Two inches of fresh snow sits over the crust above 7,000 feet. The crusts were breakable in some areas but more supportable at mid-elevations. Looking into the Bear Creek drainage, all the large north-facing slide paths east of Skypilot had large, up to D3, wet slides that released during the storm sometime Monday(2/28) or Tuesday (3/1).  

Yesterday, the snow stayed thoroughly saturated and wet at elevations below 6,000 feet. Last night the snowpack got a sold refreeze. With the sun coming out today, isolated loose wet problems could develop on south aspects during the hottest part of the day. Low elevations and south faces lost a lot of snow from melting in the rainstorm. The good news is that the road access is beginning to open up.

Ski and ride safe. 

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