Bollettino valanghe

Seeley Lake

West Central Montana Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

It is possible to trigger a windslab avalanche today, at upper elevations, on multiple aspects due to shifting winds. Make careful assessments of wind features today and avoid wind loaded slopes over 35º. Loose dry avalanches are likely where the snow is not wind drifted. Take care around terrain traps where entrained sluff could push you into or over hazards. 

Problemi valanghivi

  • Wind Slabs

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

    Multiple aspects hold reactive windslab. Tuesday and Wednesday, easterly winds loaded west slopes. Last night strong winds switched back to westerly and are reloading east slopes. Wind slab is forming on top of crusts from last week’s rain event and facets on previously scoured faces. Wind slab is found mainly at and below ridgeline, but exposed areas midslope may be cross-loaded—exercise caution in start zones and around the loaded edges of gullies. 

    Drifted snow, cornices, wide pillows, hollow-sounding snow, and shooting cracks all indicate the presence of windslab.  As windslab sets up and gets stiffer, or if it’s very specific in its location, you may not get shooting cracks as a warning sign. A good policy is to avoid any steep start zone expected to be wind loaded.

    Today avoid wind loaded slopes over 35º. Take special care to assess wind effects on multiple aspects. 

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1

    Up to 6” of new snow fell on Tuesday. Cold temperatures yesterday and last night have kept it soft and unconsolidated. Loose dry avalanches are likely on slopes over 38º. Due to the presence of the underlying crust from last week's rain, these were running far and fast yesterday.

    While mostly small, sluffs can create issues if encountered around terrain traps where they could push you off your feet and into or over train traps such as gullies or cliffs. Manage loose dry slides by letting them run before skiing, cutting out of sliding snow to high points, and riding ridges rather than gullies in steep terrain.

Avalanche Discussion

Since the last forecast, up to 6” of snow has fallen in the Seeley zone, temperatures dipped to -15  overnight. Winds have switched from west to east and back to the west, loading multiple aspects.

Today, expect temperatures to the mid-20s. Winds are out of the west and moderate to strong. Partial cloud cover may limit solar warming. 

Sub-zero overnight temperatures and cold days have kept the new snow soft and promoted faceting. This has kept cohesive storm slab from forming. As temperatures warm over the next couple of days, we could see more cohesion in the snow and potential slabs on the rain crust. Slab formation will be accelerated on south aspects if the sun appears. 

The crust from last week's rain is still prominent and impacts skiing in most places. It’s currently proving to be a slick bed surface for loose dry avalanches. When the next round of snow, arriving Sunday, buries it deeper with a cohesive slab, we could see a widespread avalanche cycle.

Please let us know what you are finding out there. You can submit observations here.

Ski and ride safe.

Regioni coperte