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

Recent avalanches and whumpfing collapses tell us it remains possible to trigger a slab 1 to 2 feet thick. Avoid convex rollovers and stick to planar slopes with clean runouts. Impressive wind speeds continue to blow whatever soft snow is left on the surface into thin slabs. Steer around pockets of drifted snow.

Avalanche problems

  • Persistent Slabs

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

    On Sunday, a large avalanche failed in the northern Whitefish Range. Riders in the Flathead Range felt loud audible collapses on the same day. Meanwhile, other riders have reported no signs of instability. Your chances of triggering a slide are higher in areas where a slab of stiffer snow or thicker snow sits above weak layers of faceted crusts and buried surface hoar. If your decisions take you into steep terrain, choose slopes that are planar or convex. Select terrain with smooth, clean runouts and keep a partner in a safe location.

    (2/6/2022)

    A large avalanche in Clarence Creek, in the northern Whitefish Range. Possibly triggered by a snowmobile.

    Photo: Seth Carbonari

  • Wind Slabs

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

    Strong winds blasted the highest ridgelines on Monday and continue to blow at speeds capable of transporting snow. Expect freshly formed drifts to be stubborn and isolated. Slabs of drifted snow should be easy to identify and avoid. Textured or pillowy-looking surfaces are your visual clues of drifted snow. Use small test slopes to assess whether slabs are reactive or not. If you see shooting cracks, stick to slopes sheltered from the wind or less than about 35 degrees.

    (2/7/2022)

    Thsi extended column test propagated with 16 taps. Others nearby, on slopes where the wind hadn't stiffened the slab, did not propagate

    Photo: Kyle Bitney

Avalanche Discussion

Buried weak layers of faceted crusts and surface hoar continue to show signs of instability. On Monday, a rider in the Flathead Range found propagating results with extended column tests. On Sunday, we received reports of audible collapses in the Flathead Range, as well as a large (2 of 5) avalanche that failed in the northern Whitefish Range. Other riders report no signs of instability. It appears these signs of instbaility are more common in areas where roughly a foot or more of snow sits above the weak layer in the Whitefish and Flathead Range. All of the reported human-triggered avalanches have occurred in the Whitefish Range.

A freezing rain crust up to 1 cm thick in the Swan Range is keeping the persistent slab problem at bay below 6500 feet. On Monday, Guy and I covered a lot of ground in the northern Swan looking for recent avalanches and testing buried weak layers. We found no noteworthy avalanches and felt a rain crust on all aspects and up to our highpoint of 6800 feet. Another rider found this rain crust on the west side of the range near Peters Ridge and up to the same elevation. The lingering concern is start zones above this elevation where there is uncertainty if this crust exists and where thicker slabs rest over weak snow.

Wind speeds up to 50 mph at the highest ridgelines still manage to find snow to blow around. You may find a shallow wind slab on the leeward side of exposed ridges. The more consequential scenario is if a small wind slab triggers a buried weak layer further down. Steer around heavily wind-loaded areas.

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