Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
View on map

Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

At upper elevations, conditions remain dangerous. You can trigger surprisingly wide and deep slabs of new and drifted snow on steep slopes, and natural avalanches remain possible. Below about 7000 feet, wet snow avalanches are the primary hazard. Both dry and wet snow avalanches can run unusually long distances, even into valley bottoms. Avoid being on or below steep slopes. The avalanche hazard will diminish with cooler temperatures tonight and tomorrow.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    Below about 7000, you can trigger dangerous wet snow avalanches on slopes steeper than about 35 degrees. These are most likely between 6000 and 7000 feet, where wet snow sits over the recent storm snow. Natural and triggered slides will entrain dramatic amounts of saturated snow and run long distances. Gullies can funnel this debris to valley floors. Avoid being on or below steep slopes. Where the snowpack is saturated and drainage has established - below about 6000 feet - these slides will be smaller and harder to trigger.

    (3/2/2022)

    Large rollerballs typically indicate dry snow that's getting wet - a sign of wet snow instability

    Photo: Clancy Nelson

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    Above the rain/ snowline - about 7000 feet to start the day, then dropping - you can trigger slabs of recent and drifted snow 1 to 3 feet thick on steep slopes. Your likelihood of triggering these increases as slope angle increases. Natural avalanches remain possible. Small slides can turn into monsters when the debris descends into elevations where the snow is wet. Above the snowline, the remarkable amounts of storm snow may have created slabs cohesive enough to wrap across terrain features and pull out multiple start zones. Avoid being on or under slopes steeper than about 35 degrees.

    (2/28/2022)

    A soft soft slab intentionally triggered in the southern Whitefish Range. Additional snow has fallen since the event, making the potential size of triggered slides much larger. 

    Photo: Dundas

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–3

    On isolated slopes, debris from slab and wet snow avalanches may release slabs that break on crusts or weak snow buried well below the snow surface. These step-down avalanches can be much wider, break around terrain features and into multiple start zones. Factor that potential into your terrain evaluation: if this slope surprised me with a large, deep avalanche, where would the debris carry me? Snowpack tests can help you identify slopes where these older weak layers exist. Avoiding slopes steeper than about 35 degrees is the most reliable way of reducing your exposure to this relatively isolated hazard.

Avalanche Discussion

"It's been so wet even my dog doesn't want to go outside," a friend told me last night. "And he's a lab." The lack of language-capable creatures in the backcountry - and lack of reports - does increase our uncertainty about conditions. Keep that in mind if you do get out today, and adjust your plans, route, and practices to meet the conditions you find.

Clancy and Cam both ventured out Wednesday, returning with reports of easily-triggered wet snow avalanches, water percolating through the upper snowpack, and rough travel conditions. Wet snow avalanches remain the primary hazard today. Most will involve cohesionless surface snow; with water percolating down to buried crusts and weak layers, isolated wet slabs are also possible. While these will be most likely above about 6000 feet, the debris can run into low elevations and valley bottoms. In the past two days, debris from two different slides has come within a hundred yards or less of US Highway 2 in the Middle Fork. Those slides are reminders - announcements? - that staying away from avalanche runouts is a simple way to extend your backcountry career. Gullies that funnel debris are especially exposed to wet snow avalanches.

There's dry snow above about 7000 feet, with snow lines lowering through the day. Lots of new snow. Lots and lots of new snow. The water totals from this storm are impressive - 4 to 5 inches, maybe more. That's enough to create thick slabs that wrap across multiple start zones, creating the potential for very large avalanches. With continued snowfall today, natural avalanches remain possible. And once running, these may entrain remarkable amounts of debris, especially as the descend into lower elevations where the snow is wet. Another good reason to stay out from under steep slopes. On isolated slopes, slabs of new and drifted snow may step down to weak layers buried in January or early February. 

Regions covered