Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 8 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Look for and avoid slabs of drifted snow 8 inches or more thick on leeward, upper-elevation slopes. These will continue to build today as a storm approaches. If the storm arrives early, the avalanche danger will rise sooner than forecast. Dial back your exposure to avalanche terrain if you see more than a few inches of snow accumulate through the day. 

Avalanche problems

  • Wind Slabs

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

    Southwest winds have formed fresh slabs of drifted snow on typical leeward slopes (NW-N-SE) at upper elevations. These will continue building today. The slabs will likely be shallow but sensitive to a rider’s weight. They can be dangerous when they’re more than about 8 inches thick or above a terrain trap.  

    Areas below ridgelines, saddles, and sidewalls of gullies are classic places to encounter a fresh wind slab. Notice the physical change in the snow as you travel. Wind-loaded slopes will appear textured, dune-shaped, or hollow-sounding. You’re riding or stepping onto a fresh wind slab if you find the snow beneath you becoming firmer and chalky. 

    Pick a path that provides better skiing and riding in softer snow. Enter slopes from the side and avoid having to travel straight down the fall line and over areas of wind effect.

    On isolated slopes, triggered slabs could step down to persistent weak layers buried 1 to 2 feet deep.

    (3/9/2024)

    This photo, from a previous season, highlights wind effects on the crest of the Whitefish Range.  Avoiding fresh wind slabs and navigating terrain, as these snowbikers did, will provide a more enjoyable and safer day.

    Photo: Flathead Avalanche Center

Avalanche Discussion

2026 is making some headway on its New Year's resolution to return to its roots and be more winter in the winter. Snowfall tapered off Monday morning with snowlines within a 1000 feet of the valley floors. And the snow in the mountains was relatively low density. Progress, 2026, progress. Keep it up.

That low-density snow was easily whipped around by moderate to strong southwesterly winds. These increased overnight. Today's primary avalanche hazard will be slabs of drifted snow top-loaded onto steep, upper elevation slopes. I expect some cross-loading on mid-slope features as well, since last night's winds were strong and gusty. Before dropping or riding into spots that collect wind-blown snow - the backsides of ridges, the downwind sides of passes between peaks, the leeward sides of cross-loaded gullies - do a careful check of conditions and consequences. Cross steep slopes with wind-affected snow off your "let's ride" list today, especially if they're above terrain traps. 

Persistent slabs... To list, or not to list, that is the question here at the forecast center. We've had isolated reports of instability involving the facets and surface hoar buried Friday. More reports that it's unreactive in tests. Small storms are incrementally loading this layer. My guess is that it's becoming sensitive to the weight of a rider or snowmachine on isolated, upper-elevation slopes where there's a wind-stiffened slab a foot or more thick above it. That's pretty much the same terrain where today's Wind Slab avalanche hazard exists. So any shallow triggered slabs today could step down. That's a bonus reason for carefully assessing that terrain. Better riding exists on sheltered slopes, so you could minimize your exposure to both hazards by sticking to slopes where the snow surface is soft and the slope angle is less than about 35 degrees. Take heed of any collapses or shooting cracks; these are clear signs that the buried persistent weak layers don't like your weight. Please submit an obs if you encounter these conditions. 

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