Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

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

Steer away from slopes recently loaded by snow and wind. Shooting cracks are signs that slabs are ripe for triggering. Reduce the chances of triggering a larger, more destructive avalanche by sticking to slopes less than 35 degrees. 

 

Avalanche problems

  • Wind Slabs

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

     Give wind-loaded terrain a wide margin today in areas favored by recent snowfall. Slabs will be thicker and more dangerous along ridge crests and where winds funnel through terrain features. Visual clues of a Wind Slab are dune-shaped drifts and textured surfaces. Shooting cracks are indicators the slab is ripe for triggering in steep terrain.

    It may be possible to trigger a slab avalanche in terrain sheltered from the wind that received more than 8 inches of recent snow. Recent snow may rest on recently formed weak layers. Avalanches failing at the new/old snow interface may break wider than you expect.  

    (2/27/2024)

    A shooting crack is an indicator of unstable snow. These are common in areas where 8 or more inches of snow falls, or is transported by wind. Signs like this should direct you toward lower-angled terrain. 

    Photo: Jeff Metsky

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    Although weak layers associated with crusts exist in the Swan Range, we have yet to receive a reported avalanche on these layers. Although it is unlikely to trigger an avalanche failing deep in the snowpack in the Swan Range, avalanche activity in the nearby ranges is concerning enough to keep it listed as a problem. New snow and wind are thickening slabs on top of these weak layers.

    A faceted crust buried 1 to 2 feet down is the culprit for human-triggered avalanches in the Whitefish Range, and is found in the Flathead and Swan Ranges. Avalanche activity on this layer is more focused on south and east aspects. 

Avalanche Discussion

Storm totals are starting to tally up at remote weather stations. In the past 48 hours, Noisy Basin in the Swan Range picked up .7 inches of Snow Water Equivalent (SWE), Stahl in the northern Whitefish Range picked up 1.2 inches of SWE, and Flattop in central Glacier National Park picked up 1.4 inches SWE. Tunnel Ridge in the Flathead Range gained 10 inches of settled snow since the start of the storm. The driver is the southwest winds that accompanied this precipitation. Winds turned out gusts 40 to 50 mph at remote weather stations. A few more inches and increased winds will thicken recently formed slabs.

There are a couple of different faceted crusts to keep an eye on. The first one you will see in the snowpack is 1 to 2 feet below the surface. Reported avalanche activity on this layer is more common in the Whitefish Range. The second layer is the one responsible for producing the largest avalanches. It is faceted snow above the early February crust buried 2 to 4+ feet deep. The Flathead Range and Glacier National Park are the hotspots for reported avalanche activity failing at this interface.

Weak snow above the early February crust has a bad reputation throughout the northwest. It extends north into Canada, south to Missoula, and west to Washington. Unfortunately, this interface is the culprit of close calls, accidents, and fatalities. This history continues to be the topic of conversation within the forecast team. 

Regions covered