Avalanche forecast

Whitefish Range

Flathead Avalanche Center
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Avalanche danger

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

Assess wind-stiffened slabs for cracking before committing to steep, exposed terrain. On sheltered slopes, with no supportable crust below the recent snow, you could still trigger slabs that break on weak layers buried one to two feet deep. If you want to keep it simple, you can avoid both hazards by riding planar slopes less than about 35 degrees.

Avalanche problems

  • Wind Slabs

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

    Watch for small, soft, freshly drifted snow and older, firmer wind slabs on steep slopes. Expect to find them on the downwind side of ridges and saddles or the sidewalls of gullies. You’ll notice rounded, rippled snow that’s firmer than in sheltered terrain. The hazard exists mainly at upper elevations, on typically leeward slopes. A few slabs may still be sensitive, further downslope, and on unusual aspects. Cracking in dense snow will tell you what slopes to avoid regardless of aspect and elevation. 

    (2/17/2022)

    Recent blustery conditions and fresh snow resulted in thin hard slabs over soft snow in John F. Stevens Canyon

    Photo: Blase Reardon

  • Persistent Slabs

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

    On isolated northerly slopes, you can still trigger a slide that breaks one to two feet deep on old, collapsible weak layers. The most likely candidates are below ridgelines, have convex profiles, and don't have hard melt-freeze crusts below the recent snow. They may be sheltered from winds by dense trees nearby. Use an inclinometer to stay off and out from under slopes like these that are more than 35 degrees.

    (2/17/2022)

    Snowpit tests revealed propagating results on a layer of buried surface hoar. This layer is responsible for our Persistent Slab problem in the Whitefish Range.

    Photo: Clancy Nelson

Avalanche Discussion

Wednesday brought a much-needed refresh with 5 to 10 inches across the region. Winds veered from southwest to east and back. Riders on Thursday reported soft snow above the crust that had made conditions so crumby. They also reported numerous dry loose and soft slab avalanches at mid-and upper-elevations. Most of these were small. Many were natural with a few skier-triggered wind slab avalanches (southeast aspect, upper-elevation, Mt. Brown; west aspect, mid-elevation, Noisy Basin; east aspect, upper-elevation, Whitefish Range).

Southwest ridgetop winds have been sustained. Since Wednesday, only a few inches have fallen. Blase and Christina found small, stubborn, firm wind slabs above 6000 feet in John Stevens Canyon Thursday. They could hear strong winds above and expected bigger slabs on higher slopes. I was northwest of WMR and found minimal wind effects and light blowing snow at mid-elevations.

Under Wednesday’s snow, the old surface was a hard crust that extends into the alpine in the Swan and Flathead zones. Most of the reported avalanches from this week slid on that crust.It’s spottier on northerly slopes in the Whitefish Range, where surface hoar is still causing some stability tests to propagate. Weak faceted snow still rests one to two feet below the surface in the Flathead zone. These persistent weak layers are mainly a concern on slopes without a supportable crust above them. 

Temperatures are forecast to be above freezing below about 6000 feet Friday. Rollerballs are the sign the loose dry snow is getting wet. If that happens, steer away from very steep slopes above terrain traps where wet debris can get you into trouble.

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