Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a very large avalanche is possible. Triggering these avalanches is most likely in wind loaded locations. These may be triggered by smaller avalanches, and where the slab is thinner.

Avalanche problems

  • Persistent Slabs

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

    Triggering a very large Persistent Slab avalanche is possible. You're most likely to trigger one of these slides in steep terrain facing W-NW-N-NE-SE terrain (plot). Thick, firm slabs rest above weak snow formed during January's drought, including surface hoar, facets, and facet + crust combinations. Although recent observations point towards an improving Persistent Slab problem, we continue to receive reports of booming collapses and have observations of large natural avalanches in the last 48 hours.Snowpack collapsing or whumpfing is a clear sign of unstable conditions. Unfortunately, you may not receive any obvious warning signs before triggering one of these large avalanches. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered.

    Additional Discussion: You may be able to trigger smaller avalanches involving only wind-drifted snow from the tail end of the storm (Wind Slabs). 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 or consequential avalanche paths where the wind formed large or stiff drifts or slabs.

    (2/6/2025) Multiple avalanche crowns on Copper Mountain's E ridgeline.

    Photo: Sawtooth Avalanche Center

Avalanche Discussion

Today is Super Bowl Sunday, which brings up a classic Bear Bryant football quote “defense wins championships.” This is also an applicable theory to apply to our current conditions. Although we’re seeing less obvious signs of instability each day since the large storm cycle of last week, we still have considerable amounts of uncertainty about how easy it is to trigger these big avalanches. A 1,500 foot wide slide released sometime between Friday evening and Saturday morning in the Galena area, and was first observed yesterday morning. This avalanche highlights the surprising nature of persistent slab avalanches and is in terrain that could easily be accidentally considered safe. Bringing your best defense is your best offense right now while we patiently wait for the weak layers to heal.

You may have noticed the discussion for both Banner and the Sawtooth-Western Smoky zones is the same, but the danger ratings are different. The reason is terrain-driven, in that there are fewer large slopes with extensive wind loading in the Banner zone.

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