Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You could trigger a large avalanche where the wind has formed drifts and stiffened the snow surface. Avalanches may break wider than expected. Anticipate loose snow avalanches in very steep, rocky terrain receiving direct sun.

Avalanche problems

  • Wind Slabs

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

    Recent storms built slabs in areas exposed to the wind. You could find sensitive slabs at any elevation, but expect them to be thicker and found in more terrain as you climb in elevation. On the northern half of the compass, slabs formed over various persistent weak layers. Triggering an avalanche may be easier on these slopes. You may be able to remotely trigger an avalanche from lower-angle terrain above, below, or to the side of steep slopes.

    Slabs often form near ridgelines, along steep mid-slope gullies, or on aprons below steep cliffs. You can reduce your chances of triggering a wind slab by avoiding slopes with obvious signs of wind-loading, such as new cornice growth and large dunes or pillows of wind-blown snow. Some slabs may not be obvious from a distance as they are masked by soft snow at the surface. A sudden stiffening of the snow you're traveling through or cracks shooting from your skis or sled can indicate an unstable slab.

    Additional Discussion: Loose snow avalanches are possible on very steep, rocky slopes receiving direct sun. These slides often initiate near the base of trees and rocks, gathering snow and growing in size as they move downhill. Rollerballs, or pinwheels, signify that the snow is heating up, and wet avalanches may soon follow.

    (3/18/2025) Wind slab avalanche near Banner Summit on Bull Trout Pt. ENE @ 8,300'. Photo: Sawtooth Avalanche Center

Avalanche Discussion

Yesterday, we observed numerous avalanches that released during our recent storms (photos). These occurred on all aspects as high precipitation intensity caused steep slopes to shed. 

So far, the largest avalanches have been observed in wind-loaded terrain on NW-N-NE-E aspects. These slopes had the weakest snow surfaces before the storm and were loaded heavily by strong SW-W wind. Today, these are the same slopes where you're most likely to get into trouble. Although spring snowpacks often stabilize quickly after storms, observations are limited, and we're exercising extra caution before stepping out into consequential terrain.

Enjoy this beautiful last day of winter, but keep your eyes and ears open for obvious signs of instability. Recent avalanches, muffled collapses, or cracking at the snow surface are your best indications that the slope you're on or connected to may be unstable. When in doubt, dial back your terrain choices; there's plenty of meadow ripping and low-angle powder to be found. 

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