Dangerous avalanche conditions will develop in areas that see 8 inches or more of new and drifted snow. Slabs are developing on old snow surfaces that may prevent them from settling and bonding. Yesterday, on steep, northerly slopes, skiers triggered small wind slabs that broke on well-preserved surface hoar and facets. New slabs will be largest below ridgelines and on leeward slopes. Choose simple, sheltered terrain with low slope angles to limit your risk.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Overnight, southwest winds continued to build slabs that began forming Saturday. Buried surface hoar and weak facets makes these wind slabs particularly scary. Skiers near Big Mountain easily triggered small wind slabs yesterday. Though we have no reports from the northern part of the range, weather station readings and observations from our neighbors in Fernie tell a similar story. You can get into real trouble today on steep leeward terrain. Recently-buried weak layers mean that you may be able to trigger slabs from their margins. They could break above you or from nearby, sheltered slopes. Give drifts an even bigger margin that usual. If you spot rounded drifts and blowing snow below ridgelines and on the sidewalls of chutes, take a big step back .
The moderate winds that observers reported over the past two days haven’t had a lot of new snow to play with, until now. Snowfall picked up late yesterday and winds continued through the night. More of the same is on tap for today, though there is some uncertainty in the weather forecast. Models diverge on the amount of new snow today. The Swan Range appears to be favored with around 8 inches or more. The Noisy Basin SNOTEL started recording heavy snowfall rates of and inch per hour early this morning. The Flathead Range and the Divide have picked up between 4 and 8 inches in the past 24 hours and could see another 3 to 5 inches today. The Whitefish Range has seen 3 to 5 inches so far and will most likely miss out on the bulk of the precip today. Wind sensors across the region continue to show moderate southwest winds ideal for redistributing snow onto leeward slopes.
New and drifting snow is accumulating on a variety of old snow surfaces that will inhibit bonding. Crusts and old hard wind drifts can act as sliding surfaces for fresh slabs. What scares me most is the weak faceted snow and surface hoar that has been reported from the Flathead and Whitefish ranges over the weekend. Skiers triggered small but touchy slabs that broke on surface hoar in the Whitefish Range over the past two days. Persistent weak layers like that will not only make new slabs more sensitive, but will prevent them from healing as quickly as they normally would. Because the troubling layers were best preserved at the margins of typically wind loaded slopes it will be harder to spot likely trigger points. Slabs can break from above you or from sheltered terrain nearby. You’ll need to give yourself an extra wide berth around new slabs today.
Bands of snow showers will continue today with the Swan Range favored. Conditions dry up tomorrow as a ridge builds to our west. A shortwave trough Wednesday may bring a shot of additional snow before condtions become calm and warm later this week.
| Monday | Monday Night | Tuesday | |
|---|---|---|---|
| Cloud Cover: | Mostly Cloudy | Partly Cloudy | Mostly Cloudy |
| Temperatures: | 22 to 28 deg. F. | 11 to 14 deg. F. | 22 to 28 deg. F. |
| Wind Direction: | West | West | Southwest |
| Wind Speed: | 13G24 | 11G22 | 11G22 |
| Snowfall: | 1" to 2" in. | 0" in. | 0" in. |
| Snow Line: | 2000' | 1500' | 1000' |
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.
