Avalanche forecast

Whitefish Range

Flathead Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

It remains possible to trigger a slab avalanche on shaded aspects (NW, N, NE, E, SE). Slabs will become larger the higher you climb. Slopes that face south and southwest are proving to be more stable.

Recent storm totals favored the central and northern Whitefish Range. Expect LOW avalanche danger at mid-elevations in the southern Whitefish Range.

Avalanche problems

  • Persistent Slabs

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

    You are most likely to find trouble on shaded aspects at mid- and upper-elevations. These are the aspects where this weekend’s storm buried weak layers of surface hoar and facets. Shaded aspects along ridge crests are also where winds drifted snow into thicker stabs.

    Reduce your chances of encountering this problem by choosing slopes that face south. If you want to ride on north and east facing slopes, pay close attention to signs of instability. Shooting cracks and whumpfing collapses are two signs you’ve found the problem. If in doubt, choose lower-angled slopes.

    (12/9/2024) Crown profile on a northeast aspect at 6500 feet. This avalanche failed on buried surface hoar. Photo: Cameron Johnson

Avalanche Discussion

We transitioned to a persistent slab avalanche problem throughout the forecast area. Unfortunately, there isn’t a clear picture to where this problem exists yet. We are most concerned about areas where winds drifted snow into cohesive slabs and areas favored by recent snowfall (N. Whitefish Range and Central Glacier National Park). Snow totals varied from a couple inches to a foot and half. This recent snow is resting on a fragile layer of surface hoar (a persistent weak layer). The variability of recent storm totals, plus the spotty, tricky nature of surface hoar, will make your field assessments critical. Here are some useful questions to ask while traveling:

  1. How much recent snow is there? You can do this with quick handpits. Dig down until you hit a crust, see a grey stripe (surface hoar), or feel for sugary snow. If you only find a few inches of recent snow, then there is not enough snow to form a slab. If you find 8+ inches of snow sitting on surface hoar, then you've likely found the problem.
  2. What aspect am I on? Slopes where this problem exists are on slopes shaded from the sun. The sun destroyed the surface hoar on solar aspects before it was buried. Observations generally describe a stable snowpack on south facing slopes.
  3. Where did wind transport snow? Continuously assess surface conditions and signs of wind drifting. Remain leery of dune-shaped drifts and pillowy-looking surfaces downwind of ridgelines and saddles. Slabs of drifted snow rest on persistent weak layers in many areas. This makes them more susceptible to triggering long after a loading event.

A storm enters the region this weekend. Models show anywhere from 5 to 15 inches of new snow with moderate to strong winds. Expect to see changing avalanche conditions soon.

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