Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
View on map

Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Don't let your guard down! You can still trigger large slab avalanches on steep slopes, from adjacent slopes, and from below. The slabs remain reactive on enough slopes that you should treat all steep terrain as guilty until proven innocent. Seek out lower-angled slopes without convex rollovers that are not exposed to steep terrain above. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    On Wednesday, the 3-week streak of triggered slides continued. Most avalanches have failed above 5,500 feet on slopes facing north to east, to southeast. On those aspects, layers of surface hoar and facets are more widespread and better preserved than on south- and west-facing terrain. Don't get suckered onto the steeps. Choose terrain with consistently low slope angles. Avoid trigger points like breakovers and areas where recent winds and settlement have stiffened the snow near the surface.

    (2/17/2021) Triggered with a small cornice drop

Avalanche Discussion

Human triggered avalanches and other signs of instability continued on Wednesday. Skiers on the southern edge of Glacier Park triggered a persistent slab avalanche with a small cornice drop onto a wind-loaded, northeast facing slope. A snow machine remotely triggered a slide 2 feet deep in the southern Whitefish Range.  A rider near Canyon Creek felt a large collapse on a south facing ridgeline. Another group experienced multiple collapses near Marias Pass.

On Tuesday, obversers reported collapsing in the Whitefish Range and in John F. Stevens Canyon. On Monday, riders triggered two persistent slab avalanches in the Whitefish Range. One large avalanche, on a southeast facing slope, was intentionally triggered with a ski cut. The other, on a northeast facing slope, broke above a skier and buried her in neck-deep debris. Cam triggered a large persistent slab with a small cornice drop in the Swan Range on Sunday.

Weak layers of buried surface hoar and facets are widespread across the region. They are 1 to 4 feet deep and rest atop the mid-January crust. They are most sensitive on north and east aspects where they were best preserved before burial in late January. Scattered collapses and stability tests indicate that these layers are less widespread, but more unpredictable, on south and west facing terrain. The overlying slab is stiffer where winds drifted snow into last weekend, or where moderating temperatures have consolidated the upper snowpack. 6-18 inches of softer snow at the surface may make them hard to identify. They don't always give consistent feedback before they fail. A lack of shooting cracks, whumpfs, and propagating test results do not provide the level of certainty you need to bet the farm. Ride slopes that are consistently less than 35 degrees, that are not exposed to avalalanche terrain above, that's the real ticket. Low angle pow is still pow - and it sounds more fun than getting caught in an avalanche on a sunny day.

Regions covered