Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Very large avalanches were remotely-triggered by skiers in this zone on each of the last two days. Triggering a similar slide is likely on many slopes today. Avalanches can be triggered from long distances away from steeper slopes and can run into gentler terrain below. Small loose snow slides will release naturally during periods of direct sunshine. Smaller natural and triggered slides can step down to the weak layers beneath, creating much larger, more destructive avalanches. 

We have issued an AVALANCHE WATCH for this zone. Avalanche danger will increase significantly overnight as an intense storm impacts the region. Natural and human-triggered avalanches will become very likely by tomorrow morning.

Avalanche problems

  • Persistent Slabs

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

    Multiple large to very large persistent slab avalanches were remotely triggered in this zone on Friday and Saturday (photo at right/above, video here). Slides occurred above Trail Creek, the East Fork of the Big Wood River, and near Baker Creek. These avalanches failed as dense, 2-3 foot thick slabs of snow. The culprit weak layer in these slides was the impressively widespread and fragile snow that developed during the December drought. Dig down and you'll find facets and/or surface hoar on shadier aspects and crust + facet combinations on sunnier slopes. 

    Triggering similar slides is likely again today. You can trigger avalanches that fail on these weak layers from long distances away from steeper slopes. Some of the triggered slides from the past two days released over 1,000' away from where the slope initially collapsed.

    The recent snow is adding significant stress to the persistent weak layers in the snowpack, and represents the first major loading event that large portions of this zone have experienced. The recent triggered slides clearly indicate that the snowpack is not reacting well to this loading. Pay attention to the terrain you are in and the terrain you are exposed to from above. 

    This large remotely-triggered persistent slab avalanche on a NE slope at 9400' above the East Fork of the Big Wood broke 250 feet wide and ran over 1000' downslope.

  • Wind Slabs

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

    The recent storm brought over a foot of snow to upper elevations and up to an inch of rain to lower elevations. Strong, southerly winds blew during the first half of the storm, building stiff wind drifts in many locations. Low-density snowfall at the end of the storm will mask the presence of these slabs. Expect to find these slabs in exposed terrain at middle and upper elevations. Cracks shooting out from your skis or machine are clear signs you've found an unstable slab. Enough snow has fallen that avalanches involving only the recent snow will be large enough to bury you. 

    Periods of bright sunshine today will melt the surface snow, causing a number of smaller loose snow avalanches to release naturally. Slides involving the new snow will be generally small but may run surprisingly quickly on the crusts and stiff surfaces underneath. Importantly, natural and triggered slides involving the recent snow can trigger the much larger, more destructive persistent slabs described above. 

Avalanche Discussion

If you head out into the mountains today, expect to find a beautiful day and dangerous avalanche conditions. The multi-day storm drew to a close last night and we will see some bright sunshine on our fresh snow this morning. Unfortunately, this fresh snow is just lipstick on our persistent slab pig. Across our Forecast area, a layer of impressively weak snow is buried underneath dense 2-3 foot thick slabs of snow. In the past two days, Brooke and I both triggered large and very large avalanches near the boundary of the Galena Summit and Eastern Mtns and Soldier and Wood River Valley Mtns zones. These slides failed hundreds of feet wide and some were triggered from over a thousand feet away. Yikes. 

One thing about our current slab+weak layer combination that is particularly concerning to me is how dense the slab has become. The density of the slab helps to keep our skis and machines floating above the weak layer. As we travel around, we may not be getting direct feedback from the snowpack, particularly in our northern and western mountains where the slab is thicker. In areas where the snowpack has remained thinner (southern and eastern mountains) the slab is a bit thinner and triggering avalanches on it will be slightly easier. Across our region, any avalanche you trigger that involves this weak snow is likely to break hundreds of feet wide (or wider) and will send a majority of the snowpack rocketing downslope. Triggering one of these slides is likely today. Direct sunshine will produce some loose snow avalanches on steep slopes that face the sun. These aren't likely to be large, but they can be effective triggers for avalanches that fail on our persistent weak layer. 

Go into the backcountry expecting to be able to trigger large to very large avalanches. These slides can fail in places that you haven't seen them before and can pull back into lower angle terrain above steeper slopes. Triggering avalanches from long distances away is likely today. Be alert to the possibility of triggering one of these slides that affect other members of your group or other groups in the mountains. Today is dangerous. Don't get distracted and don't get complacent. The goal today, again, is to come home safe. 

Regions covered