Avalanche forecast

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Significant accumulation of new snow and strong winds mean the avalanche danger is rising. Wind slabs formed from southerly wind yesterday will grow in size today. Avoid wind-loaded slopes and choose simple terrain.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Periods of strong winds from the South with extreme gusts have deposited large amounts of snow on the downwind side of ridges and cross loaded terrain features like gullies.  Wind slabs will pose a significant danger, especially on North aspects at mid and upper elevations, and could run long distances onto flat terrain connected to loaded slopes.  Avoid convex pillows and be alert for red flags like ski-length shooting cracks.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The strong winds will have scoured snow from exposed slopes, but watch for storm slabs that may have developed in sheltered areas. Continued snowfall in the forecast means storm slabs are likely to continue to be a concern for several days.

Avalanche Discussion

We toured up to Willow Peak Thursday. Snow/rain mix at 4000' changed to heavy snow midday as wind from the South gained strength. Our data pit, at 5200' on NE aspect, showed a generally right-side-up snowpack with several non-reactive storm/wind slabs in the upper 30cm. 

Strong winds from the South, with gusts up to 40mph, were transporting large amounts of new and old snow. Expect to find wind slabs on North aspects at mid and upper elevations.  Choose simple terrain. Avalanche danger is likely to increase today with continued winds and loading from new snow.

We saw some facet growth at ground level in the brush. This is a layer that I am concerned about in bigger open terrain with bare ground, bedrock or beargrass.

With daily snow in the forecast and temperatures predicted to drop to near 0 by early next week, we can cross our fingers and hope for a Christmas gift of nice right-side-up accumulation.  However, the new snow needs time to settle and bond to the existing snowpack. Until we see signs of stability, assume avalanche danger has increased and proceed with caution.

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