Avalanche forecast

Whitefish Range

Flathead Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

Overnight snow has elevated the avalanche danger. You will encounter more snow and wind as you climb in elevation. If you start to see roller balls and trees shedding snow, move to lower-angled terrain free of terrain traps or overhead hazards.

Avalanche problems

  • Storm Slabs

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

    Heavy, dense snow fell throughout the region, with the highest totals in the Swan Range, over a foot, followed by the Whitefish Range. The intensity and amount of precipitation may have left slabs of storm snow on all aspects at mid and upper elevations. Slabs will become more widespread as you gain elevation, with the thickest slabs downwind of ridgelines and saddles where southwest winds transported the new snow. Additional daytime snowfall will continue to add to storm instabilities. 

    Elevated caution is advised in steep terrain today. Look and feel for dense snow that may support the weight of your boards or machine. Monitor new snowfall totals and changes in the snow’s density, and be on the lookout for shooting cracks, which identify a sensitive slab. Any triggered slides may run long distances and entrain a dangerous amount of snow. Be cognizant of your exposure to features that increase the consequences of avalanches. These include road cuts, gully features, cliff bands, and mid-slope depressions.

    (2/24/2023)

    This image is an example of a soft slab avalanche in a sheltered location on a convexity. This type of avalanche is also known as a storm slab, and we expect them to be widespread in locations that received the most recent snow.

    Photo: Mark Dundas

  • Loose Wet

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

    Spring weather is dynamic and should continue to be on your radar. Overnight snow, rain, and afternoon warming all contribute to wet snow instabilities.  Today’s dry snow transitioning to wet for the first time will be most unstable. You will likely see rollerballs and point releases in the new snow on steep slopes as your first warning signs.

    Be on the lookout for snow falling from tree branches or shedding off rock outcroppings as an indicator of the day’s warming. Triggered and natural rollerballs growing in size and distribution prove the surface snow is losing strength. These are all signs to seek out lower-angle terrain free of overhead hazards. Limit your time spent above terrain traps, where debris can pile up and push you into places you don't want to go.

    (4/5/2024)

    Today every aspect had fields of rollerballs. We suspect that increased wet loose activity occurred in the afternoon. We didn't stay around to watch it happen. 

    Photo: Sarah Williams

Avalanche Discussion

April showers, bring the powder. The Swan Range benefitted from yesterday's southwest flow, with Noisy Basin recording 12" of settled snow and 2.4" of SWE (Snow Water Equivalent) in the past 24 hours, 1.8" of which fell overnight! Stryker Peak in the Whitefish Range picked up 8" of settled snow and 1.3" of SWE with WMR in the southern part of the range recording 0.8" of water. The Flathead Range generally receives spillover moisture when Noisy gets slammed, but the solitary weather station in this range, Tunnel Ridge, only recorded a modest couple of inches. However, I would be shocked if other nearby drainages did not record decent snow totals.

Recent north and east winds backed to the west-southwest yesterday and increased in speed throughout the day before tapering overnight. The windiest station in Flathead County, Aeneas Ridge in the Swan Range, recorded seven consecutive hours of average speeds of over 20 mph with gusts in the 30s. Wind speeds of 16 mph or greater can generally transport snow. For those familiar with this area, wrap your mind around the bountiful wind loading in the steep east and northeasterly-facing chutes that drop off Aeneas Ridge into the Picnic Lakes area. 

Yesterday (Saturday), observers enjoyed a variety of weather and snow surface conditions. Rob and I rode in the central Whitefish Range, noting 4-6 inches of moist new snow and stubborn drifts to snowmobile traffic. As the day progressed, instability was limited to trees shedding snow, rollerballs at upper elevations, and an increase in boot/sled penetrations. A professional in Spider Bowl in the Swan found 6" of new snow had accumulated above yesterday's wet supportable surface and summed up their experience well: "If you like it damp, today was a good day to get out." A seasoned observer enjoyed 8" of soft snow in Canyon Creek in the southern Whitefish Range. As they descended in elevation and the slope angle reached the mid-30s, they found the increasingly heavy snow breaking at their feet and running.

Mark will issue FAC's last daily forecast tomorrow, Monday, April 8, 2024. After that, we will continue to write conditions updates on Tuesdays and Fridays until May 3 or as conditions dictate. 

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