Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

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

New snow followed by powerful winds have left slabs of drifted snow that can be dangerous if triggered. These slabs will be highly variable in depth, and you're most likely to trigger them from their thinner edges. Slopes untouched by the winds will offer soft snow and better riding, though they may be hard to find.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    You can trigger slabs of drifted snow on steep slopes. These may break above a person, or be most sensitive to a person's weight well-below ridgelines or in unusual spots. Among these are the sides of gullies and openings in otherwise treed slopes. Shooting cracks, hard snow that feels hollow, and recent avalanches are all clues that drifted snow is unstable. Distinguish slabs of drifted snow from wind-damaged surfaces by probing, digging with your hands, or stepping off your machine. Avoid being under steep start zones where you see blowing snow and active loading. 

    (4/3/2022)

    Moderate to strong wind transport occurred throughout the day at upper elevations. Recent dry snow was easily blown around by moderate southwest winds.

    Photo: Mark Dundas

Avalanche Discussion

Snow followed by unusually high winds has left hard slabs of drifted snow at mid and upper elevations. Mid-elevation stations across the region recorded 4 to 10 inches of snow Monday, with the Flathead Range and John F. Stevens Canyon favored. The snowline looks to be about 5000 feet. Wind speeds spiked as the snowfall eased. Upper-elevation stations showed hourly average speeds of 20 to 30 mph and gusts of 40 to 65 mph Monday afternoon, with a gust of 80 at the Sperry Glacier station. Wind speeds have diminished overnight.

I'm uncertain how today's weather will develop. The models are showing significant differences in snowfall totals, favored locations, and wind speeds. My best guess is that most of the region will see snow showers and increasing winds this afternoon. I doubt many locations will see enough new snow for more wind slab development, or to create soft slabs of storm snow. Let us know if and where you find exceptions. 

Your primary avalanche concern in the backcountry today will be triggering freshly-deposited slabs of drifted snow. The trick will be identifying these, because the powerful winds have likely left wind-damaged snow surfaces even in usually sheltered areas. Look for steep slopes where wind-packed snow is six inches or more thick. Stepping off your snowmachine, probing with a ski pole, or digging quick hand blocks are quick but reliable ways to determine the thickness of drifted snow. The slabs may feel or sound hollow where they're sitting on soft snow from this weekend. These may be the most reactive slabs. Any triggered slabs may run long distances on the hard, melt-freeze crust left by the late-March warming. Hard slabs are notorious for breaking above a person, so slope cuts are not an effective tool in these conditions. 

It may be tough today to find slopes sheltered enough from the wind to preserve soft snow. They're likely densely treed slopes that are well below saddles and other terrain features that funnel winds downslope. Many windward slopes may be scoured down to the late-March melt-freeze crust, unless they pick up significant snowfall today. That might lead to dust-on-crust conditions with minor sluffing.

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, tomorrow (Wednesday), April 6, 6:30 to 7:30. No registration is necessary for this in-person event.

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