Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
View on map

Avalanche danger

Tue
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
Open full map
Out of date — this forecast expired 8 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Very dangerous avalanche conditions exist. Avalanches large enough to bury people and break trees could release on their own, and you are very likely to trigger them. Stay off of and out from beneath steep slopes. 

The backcountry Avalanche WARNING does not apply to the HWY 21 avalanche program.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–2.5

    What and where is it?  You could trigger 1-4 foot thick slabs on all aspects at middle and upper elevations. Slabs will be thicker as you gain elevation and / or enter terrain exposed to the wind. 

    How can you recognize it?  Due to the impressive snowfall amounts and warm temperatures, the slabs exist on most slopes over about 8000' and on some slopes below that. Expect to find thicker, denser slabs below exposed ridgelines and cornices, on the sides of cross-loaded gullies, and on aprons and slopes below large chutes and cliff faces. 

    How can you manage it?  The easy answer is "stay off of, away from, and out from beneath all steep slopes." In wind-sheltered areas, you're more likely to trigger slides as the slope angle increases from 30*. Some slides involving the "new snow" could behave like Persistent Slab avalanches: they break wider and higher on the slope than expected. 

    (12/18/2025) We found natural avalanches on the NE slope of the summit of Copper Mountain (8900 ft). These appeared to have released on Dec 17th and looked to be thin wind-slabs.

    Photo: Sawtooth Avalanche Center

  • Persistent Slabs

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

    What and where is it? Dense, 2-5 foot thick slabs exist on most slopes. The weak layers (crusts and weak, sugary faceted snow) are most suspect on W-NW-N-NE-E-SE facing slopes at middle and upper elevations (near and above ~8500' in this zone), but more recently buried rain and sun crusts exist on most middle and upper elevation slopes.

    How can you recognize it? Assume the slab + weak layer setup exists on all slopes. Now is not the time to try to outsmart the snowpack. Expect to experience obvious signs of instability—snowpack collapsing and cracks shooting out from your skis or sled—in many areas. 

    How can you manage it? Sadly, today's answer is "stay off of, away from, and out from beneath all steep slopes." This zone received 4-6" of water (40-60" of dense snowfall) in the past week; there is little to no margin for error today. Natural avalanches are possible, and slides can be triggered remotely—from flat terrain below, above, and to the sides of steep slopes. You could be on flat ground hundreds or thousands of feet below an avalanche starting zone and still trigger an avalanche that reaches you and your travel partners.  

    (12/20/2025) Natural avalanche on an E aspect near 8900 ft in the Beaver Ck drainage in the western Smokys.

    Photo: Jeremy Lato

Avalanche Discussion

Visibility has been non-existent, but we expect that the mountains came unglued last night and will remain about as scary as they get today. Local professionals continue to report natural avalanches, "thunderous" or "booming" snowpack collapses, and extensive snowpack cracking while avoiding avalanche terrain, including the runouts of large avalanche paths. The impressive precipitation totals from the past 24 hours and 6 days (view the Storm Totals page) are "too much too fast"; avalanches will find a weak spot in the snowpack. 

The elevated rain lines and warm temperatures have created "greasy" layers in the upper snowpack. They could behave like wet or dry avalanches and add uncertainty to the equation—we don't trust them. 

Regions covered