Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Thu
Alpine
1 · Low
Treeline
1 · Low
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Out of date — this forecast expired 2 years ago.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

You've got a few more days to enjoy generally safe avalanche conditions. In upper-elevation terrain that collects wind-blown snow, you might find isolated, thin slabs of drifted snow that remain sensitive to your weight or the weight of a machine. Expose one rider at a time, to minimize the consequences of any misjudgements about stabilty. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–1.5

    At upper elevations, you can find thin slabs of drifted snow that are sensitive to a rider's weight. While these are mostly relics of strong winds over the weekend, some fresh slabs may have formed overnight as wind speeds picked up. Regardless of their age, they can have outsized consequences in steep, rocky terrain. 

    Look for the tell-tale signs of drifted snow - smooth pillows or dunes, cornices, and a scalloped snow surface - as you approach ridgelines or the downwind sides of saddles and passes. Cracking is clear evidence that drifted snow can be unstable on steep slopes. Choose lines that don't have you riding up into leeward start zones or dropping into chutes or snowfields above cliffs, trees, or other harder-than-you-are features.

    (12/3/2024)

    Tell-tale signs of wind-drifted snow along a ridgeline above Noisy Basin. 

Avalanche Discussion

Triggering a small, thin wind slab could get you into trouble in steep, upper-elevation terrain above boulders, cliff bands, or gullies. This hazard is isolated to spots where winds were able to drift snow overnight, or where older slabs haven't yet bonded to softer, underlying snow. The fresh slabs should give themselves away by cracking. The older ones may be harder, more difficult to detect, and poor candidates for slope cuts, because they can break above you. 

Riding conditions are likely to push you to shaded slopes free from melt-freeze crusts. Often that's a devil's bargain, because shaded slopes typically harbor persistent weak layers. Such is not the case presently. Our snowpack built quickly, with no extended dry period to promote faceting and the creation of depth hoar. Below about 7000 feet, the atmospheric river left a robust, hard layer of refrozen snow that caps any weak layers that might have formed near the base of the snowpack. While we've had a occasional reports of facets near this crust, these layers aren't widespread, propagating in snowpack tests, or producing collapses or triggered slabs. 

The upshot is that it's a good time to travel up high, with a wide playing field. Avalanche hazard isn't binary, however; conditions don't toggle between "unsafe" and "safe." You can avoid stumbling into any isolated, lingering hazards with a slope-specific evaluation that includes the potential consequences of misjudging stability. What's near the ridge above as you open the throttle up a face? What's below you if you drop into a chute? Pick lines without overhead hazards or terrain features that can magnify the consequences of getting carried in debris. 

Future you will appreciate an eye on current snow surfaces as you travel, particularly if you're in terrain where you're likely to return. The near-surface snow is weakening on shady slopes, with surface hoar or slick melt-freeze crusts capping the snowpack on other slopes. Snow that falls on these surfaces is likely to create slabs sensitive to a rider's weight once precipitation returns this weekend. 

A glide crack has opened on Haskell's slide at WMR. It's unlikely to be the only one, so look above you for these unpredictable cracks as you travel under steep, sunny slopes.

There's an app for that... You can now access forecasts, observations, and weather data for our region directly from the Avy App (IOS; Android). Many features are accessible offline, so you can win  debates about the avalanche problems right in the backcountry, or submit an obs while you're driving home. 

Registration is open for this season's avalanche courses; click the links below each relevant course.

We have an Avalanche Awareness class tonight (Wednesday, December 4), at Andy's Craft House in Big Fork. Pre-registration is not required.

Regions covered