Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Today's incoming storm will develop dangerous avalanche conditions in areas favored by snowfall and wind. Expect the danger to rise as snow totals increase throughout the day and overnight. Fresh slabs will form initially on wind-drifted slopes and in sheltered locations later in the day. Cracking beneath your boards or machine directs you to seek out lower-angle terrain.

The danger may not reach HIGH until sundown or overnight.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5

    Strong westerly winds will transport today's snowfall into fresh slabs downwind of ridgelines, saddles, and on sidewalls of cross-loaded gullies. These slabs will increase in size and thickness as you gain elevation and the day progresses. Drifts, dunes, and rippled snow surfaces confirm that the wind has been working. Today's blowing snow will be an obvious sign that slabs are forming.

    As snow totals increase, storm slabs may develop in locations sheltered from the wind. These will be thinner but may become more widespread than the above-mentioned wind slabs. They can be identified by cracking at the surface in consolidated, dense snow. 

    Whether you are in sheltered or wind-affected terrain, cracking beneath your machine or boards indicates instability, directing you to lower-angle slopes free of overhead hazards. 

    Triggering a small surface slab may initiate a much larger avalanche on a buried weak layer described in our persistent slab problem below.

     

     

    (2/24/2023)

    Soft slab avalanches are a threat in sheltered terrain when a Storm Slab avalanche hazard exists.

    Photo: Mark Dundas

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    The incoming storm will add weight and stress to weak layers buried 1 to 2 feet below the surface. These layers are found above the very hard, early February ice and crust layer. This weak snow is better developed on shady, upper-elevation slopes but is also found on isolated sunny and mid-elevation slopes. 

    Recent mild temperatures have initiated the strengthening of the weak layer, but this process is notoriously slow. You may not experience any signs of instability like collapsing or cracking before triggering a slide. 

    Choose terrain free of convexities to increase your safety margin. Steer around thin areas, such as those scoured or peppered with rocks, in favor of a deeper, more consistent snowpack. Cracking beneath your boards or machine indicates an unstable slab directing you to lower-angle terrain. 

Avalanche Discussion

A robust Pacific storm system will move into the area today (Sunday), with heavy snow and blustery winds creating dangerous avalanche conditions. Snowfall and windy conditions will continue overnight and into Monday, with a Winter Storm Warning in effect from noon Sunday until 0800 Monday. 

Snowfall yesterday and overnight favored the Flathead Range and John F. Stevens Canyon areas, with 5-7 inches. Most other locations were skunked.

Today's rising danger is related to the incoming snowfall. This morning, most Swan and Whitefish Range slopes will have a generally stable snowpack. The danger will increase after several inches of new snow accumulates. The danger in the Flathead Range and southern Glacier Park is slightly elevated due to recent snow, and the danger will rise sooner in this zone.

Today's storm will favor the Flathead Range, southern Glacier Park, and interior Glacier. The avalanche danger may reach HIGH later today or overnight in these locations. Forecasted totals for other areas are less. The northern Whitefish Range will receive more than the slopes near the WMR ski area.  The Swan Range may only receive totals similar to the southern Whitefish Range. We anticipate the danger reaching CONSIDERABLE in these locations. 

Monitor changing conditions and snow totals throughout the day. With the impressive wind speeds, higher quality riding will be found in terrain sheltered from the wind. 

 

 

Regions covered