Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

You can find good riding on terrain free from recent deposits of wind-drifted snow. These conditions exist mostly on mid-elevation, shady slopes sheltered from the powerful easterly and northerly winds earlier this week. Steep slopes with hard slabs of wind-blown snow will be riskier, and offer poor riding and travel conditions. These hard slabs can be dangerous where they're 8 inches or more thick and can break in unpredictable ways. 

Avalanche problems

  • Wind Slabs

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

    You can still trigger slabs of drifted snow on steep slopes at upper elevations. Most of these slabs will be hard and hollow sounding; your board, skis, or snowmachine won't sink in much, if at all. They'll be widespread on usually windward aspects - southeast through southwest to northwest aspects. They can be dangerous where they're 8 inches or more thick. You can trigger hard slabs from areas where the slabs thin, and they can break above you. This unpredictability makes avoiding them the most straightforward way of reducing your risk. Isolated soft slabs of wind-stiffened snow may exist on other aspects or at mid-elevations. These can surprise you, so be alert for cracks and choose slopes with runouts clear of gullies, rocks, trees, and cliffs.

    (2/23/2022)

    Some cracking around skis in recently formed wind slabs

    Photo: Guy Zoellner

Avalanche Discussion

With milder temperatures and light winds today, it'll be a good day to assess the effects of the unusually sustained wind event and bitterly cold temps that started the week. So far, from the limited observations of the past few days, it appears wind slabs have developed mostly at upper elevations. These are reported to be 4 to 12" thick, and producing short cracks under the weight of a person or snowmachine. The cold temperatures are probably keeping the slabs stiff and prolonging the instability, so I wouldn't jump onto any steep slope with hard drifts just yet. These exist on atypical aspects, because the strong winds were northerly and easterly. If you venture above about 7500 feet, you may find some isolated pockets of freshly-drifted snow, thanks to a spell of strong southwesterly winds at those elevations Wednesday. 

At mid elevations and on slopes sheltered from the winds, I might adopt a stepping out mindset. That is, include steeper terrain in my plan for the day, and look for signs to turn me back on my way. These signs include small slabs or cracks on test slopes, clean shears in hand pits, shooting cracks and whumpfing. Testing for these signs is critical, because they provide good feedback about whether winds and settlement have had subtle effects on the snow, stiffening it just enough to  make it act as a slab. If my party found no evidence of this, I might commit to steep slopes with no convexities and runouts free of terrain traps. Mid-elevation terrain and wind sheltered slopes hold up to a foot of settled, dry snow from last weekend's storm, with little effect from the sun on southerly slopes so far. 

Thanks to the intrepid and hardy souls who've braved the bitterly cold temps of the past few days and submitted observations. Let us know what you see while you're out.

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