Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

You're most likely to trigger a large avalanche where the wind formed drifts or stiffened the snow surface. Triggering avalanches is less likely, but remains possible, on sheltered slopes. You may be able to trigger avalanches remotely—from flat terrain below, above, and to the sides of steep slopes.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    What and where is it: You are most likely to trigger a 2-4 foot thick avalanche on wind-exposed slopes facing the northern 2/3 of the compass. Triggering an avalanche is less likely—but not out of the question—on steep slopes that appear to be completely sheltered from the wind. The slabs rest above a variety of ugly, widespread weak layers (facets, surface hoar, crusts, and combinations).

    How can you recognize it: Watch for cornices, snow pillows, dunes, and ripples (photo). Feel for stiff snow under your feet or sled. These are signs the wind has been at work transporting snow.

    How can you manage it: Before triggering an avalanche, you may or may not experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. Avoid obviously wind-loaded slopes. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered. We can't assume tracks on a slope mean it is safe; several people could descend a slope before triggering an avalanche.

    Additional Discussion: You may be able to trigger thinner avalanches involving only the wind drifted snow from the tail end of the storm. Watch for them near ridgelines and in cross-loaded areas on the sides of gullies. The biggest hazards these soft and hard slabs pose are 1) carrying you where you don't want to go and 2) triggering the much larger Persistent Slabs discussed above as the slides move downslope. Avoid large, consequential avalanche paths where the wind formed stiff drifts or slabs.

Avalanche Discussion

In February, we have observed and received reports of far fewer avalanches in the Banner Summit zone. Sunday and Monday, regular observers saw several 1-2 foot thick avalanches that appeared to release near the end of the big storm cycle. They did not experiend any cracking or collapsing while riding and skiing for two days. 

Limited observations indicate the Banner snowpack is stabilizing, and avalanches are getting harder to trigger. But, the threat of triggering a large, unsurvivable slide is still there. Think about the consequences of a meaty slab avalanche breaking hundreds of feet wide before committing to playing on or below steep slopes with trees, creeks, lakes, or gullies where the debris would pile up.  

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