Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Southwesterly winds will drift snow into slabs that may grow large enough to bury and injure you on the leeward side of ridges and gullies. Watch for and steer around drifting snow and pillowy-looking surfaces. Allow small sluffs of loose dry snow to run past you in steep terrain while seeking out wind-sheltered slopes. Be prepared for cold temperatures.

Avalanche problems

  • Wind Slabs

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

    Overnight, wind speeds climbed and will remain at, or near, optimal speeds for transporting the low-density snow that blankets the region. This may form slabs a foot thick that can be large enough to bury and injure you. Look around for obvious clues of blowing snow and steer towards windward or wind-sheltered terrain. Don’t let your guard down on slopes that face south and west where a more stubborn wind slab formed around Christmas. Probe and feel for hard over soft snow before stepping out into steeper terrain on those aspects.

    (12/22/2021)

    Recent winds have built fragile cornices on the lee side of this ridge at 6800 feet. The blocks below show that the cornices have already failed at least once, probably triggered by previous skiers.

    Photo: Nielson

Avalanche Discussion

A quick blast of arctic air makes its way into the region again tonight. Temperatures will drop to -20 with wind chills as cold as -35. Bring extra layers and keep your plans simple. An injury or broken equipment can turn a fun outing into a life-and-death scenario.

Since late last night (Monday), wind speeds climbed and averaged 8 to 15 mph at most remote weather stations. Typically, sustained wind speeds of roughly 15 mph are optimal for transporting snow and building slabs. However, the snow that fell in the past few days is low-density snow and cold. This fluff will transport easily with lighter-than-normally-required winds, like the ones we will feel today. Winds are forecast to remain steady at 10 to 15 mph with gusts as high as 25 mph throughout the day. Expect to find slabs forming on slopes that face north and east today.

While seeking out windward and wind-sheltered terrain, probe with your pole or hop off your sled and dig a quick hole on lower angle slopes to feel for hollow drifts. Winds have blown from nearly all directions in the past week, causing wind slabs to form on unusual aspects. If you feel dense over weak snow, change aspects or keep slope angles low. I would expect these older wind slabs to be stubborn and trending towards unreactive.

On Monday, a rider in the northern Whitefish Range was able to intentionally trigger a small soft slab in an area that was effected by wind (see photo). Other observations from the past few days show minimal activity other than a few loose dry avalanches. These were harmless in size (which is why they are not listed as a problem) and easy to manage. Staying out from underneath large chutes and allowing your sluff to pass next to you are two simple ways to not allow a little debris to push you around and make them dangerous.

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