New snow instabilities are increasing the avalanche danger today. Be cautious in areas that have received more than 8 inches of new snow, or near steep terrain where winds have transported snow into thicker, more dangerous slabs. You can safely enjoy the new snow by seeking out wind-sheltered terrain with slope angles less than 35 degrees.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
With increasing elevation comes increasing danger. In the last 12 hours the Swan Range has received up to a foot of new snow with moderate winds, with another 5" to 10" in Expect storm slabs to be located on all aspects and thicker slabs located on the leeward side of ridgelines and cross-loaded gullies where winds have transported snow. Today slabs will be reactive to a person's body or machine, and could be large enough to bury or injure you. Cracking in the new snow on steep test slopes is a sign to stay off of steeper, more consequential terrain.
Across the region, the weather stations are showing a wide spread of overnight storm totals. The Swan Range picked up roughly a foot of new snow (1" of SWE), while the Whitefish Range, Flathead Range, and Glacier National Park sensors are showing only 2 to 3 inches. We are expecting another 2" to 10" today, favoring the Swan Range again. The new snow is accumulating on soft snow sitting on a rain crust. In areas that saw smaller storm totals, winds will be driving the primary instabilities today. Select your terrain to accommodate how winds are interacting with the new snow. If you see drifted snow with depths greater than 8 inches, seek wind-sheltered terrain. Slabs will be thicker and more widespread in the Swan Range, and can expand into wind protected terrain because of the larger storm totals. Warm temperatures and rain at low elevations will likely create rollerballs and the potential for small wet loose avalanches. Be careful on steep pitches above terrain traps at lower elevations to avoid being pushed around by wet snow.
While new and windblown instabilities are today's primary concerns, we remain leery of deep instabilities, particularly in the Flathead Range. Very large, destructive avalanches have been the highlight of this month. Continuous snowfall, loading, and large temperature swings overburdened weak layers near the ground, causing numerous deep slab avalanches over the past few weeks. Shaded aspects in the uppermost elevations, like the ones found in the Flathead Range and Glacier National Park, are the areas that harbored the weakest snow. Here is a graphic that highlights activity failing on persistent weak layers near the ground. Deep slab avalanches are one of the most difficult avalanche problems to predict. This, along with their destructive nature, directs us to conservative terrain choices at that upper elevation band. Be patient and allow time for this problem to heal. We also received a second-hand report of an avalanche that occurred in the last few days, which crossed Red Meadow Road in the Northern Whitefish Range. If anyone travels into that zone today, we would love to get more information on the nature of that avalanche.
Lingering showers will taper off around noon today. Expect 1 to 4 inches of snow in the Whitefish Range, Flathead Range and Glacier Nation Park. The Swan is favored with a possibility of 5 to 10 inches of snow. Winds will be hovering around 15 MPH with gusts as strong as 30. Temperatures will be in the upper 20s and low 30s. An active weather pattern will persist through the week after a brief lul today.
| Monday | Monday Night | Tuesday | |
|---|---|---|---|
| Cloud Cover: | Mostly Cloudy | Mostly Cloudy | Overcast |
| Temperatures: | 26 to 32 deg. F. | 18 to 22 deg. F. | 27 to 33 deg. F. |
| Wind Direction: | Southwest | Southwest | South |
| Wind Speed: | 18G32 | 20G32 | 16G28 |
| Snowfall: | 5" to 10" in. | 2" to 3" in. | 8" to 14" in. |
| Snow Line: | 3500' | 3000' | 3000' |
This forecast applies only to backcountry areas outside established ski area boundaries. The forecast describes general avalanche conditions and local variations always occur. This forecast expires at midnight on the posted day unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.
