Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

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

Increasing winds will drift new snow into reactive slabs that may become large enough to bury and injure you. Large natural avalanches failed recently due to wind transported snow in the Flathead range. Stick to terrain sheltered from the wind and pay attention to new snow accumulations. Dial slope angles back to less than 35 degrees if you see signs of shooting cracks from your boards or machine.

Avalanche problems

  • Wind Slabs

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

    Many generations of wind slabs exist in varying aspects. Today, you will likely encounter freshly formed, reactive slabs on aspects that face north through east. Today’s wind slabs will be more dangerous where 6 or more inches of new snow falls or in areas where an underlying, harder wind slab exists. Stubborn, hard wind slabs can be found on all aspects above roughly 6000 feet. Look and feel for hard over weak snow before stepping out into steeper terrain. Hedge your bets by choosing terrain sheltered from the wind.

    (1/2/2022)

    This cropped image is from an original photo of a wind slab avalanche on an east aspect at upper elevations.  This face receives cross-loading from southwesterly winds, which likely lead to failure.

    Photo: Michael Reavis

Avalanche Discussion

Over the weekend, we received reports of natural and human-triggered avalanches in the wind drifted snow (observation, observation). Two large natural wind slab avalanches failed recently in the Flathead Range, one of which appears to have propagated thousands of feet wide (observation). Riders could trigger small slabs or initiate shooting cracks in wind-affected snow down to about 5500 feet in elevation.

Cold temperatures over the past week caused large temperature gradients in the upper part of the snowpack, driving the faceting process. New and drifting snow will fall onto weak surfaces, which will cause avalanches to propagate wider and run further than expected. This is the same reason why recent natural avalanches propagated as wide as they did.

Today, incoming moisture will glance the northern half of the Whitefish Range, where up to 8 inches of new snow is expected. The southern half of the Whitefish Range, the Flathead Range, the Swan Range, and Glacier National Park will likely see 1 to 4 inches of new snow by nightfall. Winds are forecast to increase with speeds averaging around 15 mph with gusts up to 30 mph out of the southwest. Today’s avalanche danger will be driven by incoming precipitation and winds.

We’ve been fortunate to have relatively stable conditions over the past week, allowing us to step out into larger terrain. Now is when we begin to dial it back and choose simpler terrain in areas that see increased precipitation totals. An atmospheric river is expected to impact the forecast area later in the week. Pay attention to obvious signs of instability, such as shooting cracks, whumpfing collapses, and recent avalanches.

Regions covered