Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You are most likely to trigger a large avalanche on shadier middle and upper elevation slopes where the wind formed drifts or stiffened the snow. You may be able to trigger slides remotely—from flat terrain below, above, and to the sides of steep slopes.

Tonight, intense snowfall and wind will cause the danger to spike.  Avalanche Warnings may be issued. Have a safe exit strategy in case the storm arrives earlier than expected. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    You could trigger wide, 1-2 foot thick avalanches where wind formed slabs above weak snow (facets, crust + facet combos, and isolated surface hoar) that developed during a month-long, January-February drought. The weak layers are ugliest on NW-N-NE-E aspects at middle elevations and just above the middle-to-upper elevation transition.

    Thursday's remotely triggered avalanche in the White Cloud Mountains is a good reminder that Persistent Slab avalanche problems are slow to heal and can involve surprisingly soft slabs; this avalanche released several days after any snowfall. Snowpack cracking and collapsing are clear signs of unstable conditions. However, a lack of these obvious warning signs doesn't mean you're in the clear.

    Persistent Slabs can release in surprising ways:

    • They can break above you
    • Avalanches may be much wider than expected
    • You can trigger them from a distance—above, below, or to the sides of the avalanche crown

    What's the easiest way to reduce the chances of finding trouble? Avoid steep, middle and upper elevation slopes facing the shady side of the compass (NW-N-NE-E) if you suspect or feel that a slab (stiffer, but not crusty, snow) has formed. Triggering large avalanches is much less likely where the upper 1-2 feet of the snowpack is soft and fluffy. 

    Additional Discussion - Wind Slabs: In typically windy, upper elevation and alpine terrain, the last storm formed wind slabs above slick crusts and hard, wind-hammered surfaces. Although these slopes do not have any glaring weak layers below the slabs, the weight of a skier or snowmobiler could be enough to trigger an avalanche. Be on the lookout for large dunes or drifts, clear signs the wind has transported a lot of snow. Although likely to be small, these slides can have big consequences in big terrain. 

    (2/12/2026) We triggered this small persistent slab avalanche from low on the slope when a collapse traveled back uphill to release this steeper pocket. 

    We were surprised by how far this collapse traveled (~50’) given the thin soft slab. 

    White Cloud Mtns, NE 9250'.

    Photo: Sawtooth Avalanche Center

Avalanche Discussion

Tonight's storm will produce natural avalanche activity. Plan to get out of the mountains before dark, and make sure you have a safe exit strategy in case the powerful storm arrives earlier than forecast. 

We need a slab, a weak layer, and a steep slope to have a slab avalanche. The most dangerous slopes exist where the slab and weak layer distributions overlap:

  • The slab: During the last storm, wind formed slabs or stiffened the new snow in the upper part of middle elevations, and at upper elevations. The slabs are now covered by fresh snow on many slopes and are challenging to spot if only relying on the typical visual clues. You can use your sled, poles, or skis to feel for stiffness changes in the upper 2 feet of the snowpack. 
  • The weak layer: As described above, facets are weakest and most widespread on NW-N-NE-E aspects at middle elevations. 

However, not every steep slope that fits the "slab + weak layer overlap" description has the right set-up to produce avalanches. You might go the whole day without receiving any obvious signs of instability and then trigger a slide. All it may take is finding the weakest buried facets and/or a slightly stiffer slab. Subtle changes in aspect or elevation could tip the stabilty scale the wrong way. Precisely predicting slope-scale stability is currently challenging.

Loose Snow avalanches (sluffs): In recent days, observers reported small sluffs in very steep terrain lacking a slab. These are most likely on wind-sheltered NW-N-NE facing slopes approaching or over 40 degrees in steepness. While these avalanches are generally small, they can be dangerous in consequential terrain, pushing you towards cliffs, trees, or other hazards. Dry Loose avalanches typically start small beneath your skis or sled and grow as they descend. Managing this problem is often as simple as slowing down and allowing the sluff to run ahead of you.

Regioni coperte