Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

A generally stable snowpack keeps the avalanche danger LOW this morning. Today's developing storm may form slabs of drifted snow reactive to the weight of a rider or their snowmachine. We anticipate the avalanche danger to rise on wind-loaded slopes through the day  

Problemi valanghivi

  • Wind Slabs

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

    As today's storm develops, fresh snow and wind may form thin slabs of drifted snow by this afternoon. Slabs should be small and easy to navigate around. The exception would be areas favored by snow and wind, where you may find slabs large enough to bury a person. Clues to identifying this problem include noting blowing snow as you gain elevation, a pillowed look to the snow surface, and cracking beneath you. Slabs may form on a crust which might inhibit bonding. Stick to scoured slopes or those sheltered from the wind for a safer experience.

    (2/4/2022)

    Wind slab triggered on a test slope in southern Glacier National Park. 

    Photo: Ted Steiner

Avalanche Discussion

Friday's temperatures continued the trend of round-the-clock below freezing at upper elevation weather stations and mostly below freezing at mid-elevation stations. Multiple days of cool weather have ended the threat of wet snow instabilities deeper in the pack. The week-long balmy weather followed by cool conditions has left us with a stout crust that I found 6-8 inches thick at 6000' on north and south aspects Thursday. Our dependable Swan observer noted a thick supportable crust on north and south slopes around 6000 feet Friday. A party in the Flathead Range didn't mention the crust, but they observed snow transported by strong westerly winds along ridgelines with slopes either scoured or holding 2-4 inches of snow. 

We have added Wind Slab to the problem list for the first time since March 17. Today, a quick-hitting cold front will move into the Flathead, bringing several inches of snow and breezy conditions. Before the snow arrives, the avalanche danger will remain at LOW. If the forecast verifies, sometime this afternoon, the danger may rise to MODERATE on wind-loaded slopes at upper elevations. Windward slopes at upper elevations will remain at LOW through the day.

Recent cool weather has allowed us to remove Cornice Fall from the problem list. We became concerned about these whale-sized features during the recent balmy weather and first listed them as a problem on March 23. Prolonged warming can initiate the calving of chunks or an even more significant failure at their roots. Once warmed, snow features of this size require substantial time to cool, refreeze, and stabilize. Although we don't anticipate natural cornice fall in the next few days, we encourage you, as always, to remain far back from the edge during traveling ridgelines because these overhanging features tend to break further back than anticipated.

Each Friday, FAC produces a weekly summary text and video of weather, snowpack, and avalanche conditions. You can find the video in the media section below or both products in the Conditions Blog tab or here.

Join us for our last education event of the season. Topics Class! The Scoop on Spring Touring, Wednesday, April 6, 6:30 to 7:30. No registration is necessary for this in-person event.

 

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