Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 8 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous avalanche conditions exist. Your odds of triggering a slide increase as you climb into windier terrain, particularly on slopes that face away from the afternoon sun. Expect the danger to rise sharply tonight as another powerful storm impacts the region.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    You could trigger 1-2 foot thick slabs in wind-loaded terrain. The size and chance of avalanches will increase as you climb into windier terrain at upper elevations. Avalanches could be wider than you expect, and easier to trigger where storm snow buried slick crusts, crusts + facets, or surface hoar.

    Yesterday's strong wind blew from the SW-W-WNW, forming slabs in many areas, and small fresh slabs may begin to form by the end of the day today. Look for them near or below ridgelines, along mid-slope ribs, and on aprons beneath chutes. Cracks shooting out in front of your sled or boards mean you've found a sensitive slab. You can manage your exposure to this problem by identifying and avoiding wind-loaded slopes.

  • Persistent Slabs

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

    You're most likely to trigger a Persistent Slab avalanche on NW-NE-E-SE facing slopes at middle and upper elevations (near and above ~8500' in this zone), holding both thick slabs and suspect crust + facet combinations.

    Cracks shooting out from you and "whumpfing" sounds as the snowpack collapses are red flags that indicate unstable conditions. If you experience these obvious signs of instability, avoid steep slopes with similar appearances, aspects, elevations, and snowpack depths. 

    Avalanches involving these layers could be very large and likely unsurvivable. Persistent Slabs often break wider than you'd expect, and can be triggered remotely—from gentler terrain above, below, or to the sides of steep slopes.

Avalanche Discussion

After a break in the action last night, storms return this afternoon. The Banner Summit Zone is expected to pick up 5-7" of new snow by sundown, accompanied by increasing SW wind. This combination may be enough to form thin, fresh wind slabs that will overlap yesterday's wind slabs. Wind Slabs may be dangerous on their own, but they also increase the chance of very large avalanches breaking on persistent weak layers buried deeper in the snowpack. Expect the danger to rise overnight as winds ramp up and heavy snowfall continues. 

Regions covered