Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

You're most likely to trigger a large avalanche on steep slopes facing the northern two-thirds of the compass. 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
    2–2.5

    Slabs formed in early February rest above a variety of ugly, widespread, weak layers (facets, surface hoars, crusts, and combinations). You are most likely to trigger a 2-4 foot thick avalanche where:

    • The slope or terrain you're connected to is steeper than about 35 degrees
    • The slope faces the northern 2/3 of the compass
    • The slab is less than about 3' thick—relatively shallower spots may exist where the wind frequently blows, and the slab is not uniformly thick.

    Before triggering an avalanche, you may or may not experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. 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.

Avalanche Discussion

Snowfall this afternoon will bring 2-4" to this zone by 5 PM, but not enough to significantly change the avalanche hazard. Snow amounts and avalanche danger will increase later this evening and into tomorrow.

In early February, we 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 experience 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 remains. Consider 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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