Another round of new snow and wind has drifted slabs onto leeward terrain features. These reactive slabs will be covering more stubborn, but more dangerous hard slabs. While seeking wind-sheltered terrain, be cautious around steep rollovers and rocky start zones. This is where you are more likely to trigger a persistent slab avalanche that can be large enough to bury and injure you. Hedge your bets by riding one at a time and choosing terrain with clean runouts.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Roughly 2 to 5 inches of snow fell overnight with another trace to 2 inches are expected today. Winds bumped back up to speeds that are prime for drifting snow. I suspect fresh wind slabs will be more reactive in areas where wind deposited slabs onto recently buried crusts. Signs of drifting snow and pillowy surfaces are your cues to seek wind-sheltered terrain.
One thing that is for sure, there are numerous persistent weak layers buried throughout the snowpack. Faceted crusts and buried surface hoar are the culprits of most of the human and natural triggered avalanches occurring in the past two weeks. Steer away from rocky, complex start zones, and be wary of steep rollovers further downslope. This is the kind of terrain where you are more likely to collapse one of these weak layers causing an avalanche large enough to bury and injure you.
Over the past week, we have received a range of 2 to 5 inches of snow water equivalent (SWE) throughout the region. This has brought roughly 10 to 20 inches of new, settled snow. Since January 2nd, winds have blown almost consistently at 15 mph with gusts as high as 66 mph which has drifted snow into many generations of wind slabs. With moderate wind speeds overnight and into today, a new generation is currently growing and could be large enough to bury or injure you. New wind slabs may be more reactive than the previous batch, because they will be sitting on a recently buried crust in many locations. This crust is found as high as 7200 feet in Glacier National Park and extended into upper elevations in the Swan Range. Continue to be cautious on leeward facing slopes and give wind slabs more time to settle out.
Yesterday, professional observers in the Swan Range spotted recent natural avalanches. These likely failed on a layer of surface hoar they found 1 to 2 feet below the surface. I suspect this layer to be widely distributed throughout the Swan Range, and likely more isolated throughout the rest of the forecast area. Another observation came in of a recent avalanche near treeline in the Flathead Range. We are unsure what kind of layer this avalanche failed on. There is a degree of uncertainty with the distribution and sensitivity of this surface hoar layer. The very terrain that you will want to go to, to avoid wind slabs, will be the most likely terrain that this layer is buried. The snowpack is complicated. It should drive you towards simpler, less consequential terrain.
Expect moderate to strong winds out of the southwest today. Snow showers will linger throughout the day bringing a trace to 2 inches of new snow. Temperatures will be in the mid to high twenties at around 6000 feet.
| Tuesday | Tuesday Night | Wednesday | |
|---|---|---|---|
| Cloud Cover: | Mostly Cloudy | Partly Cloudy | Mostly Cloudy |
| Temperatures: | 22 to 28 deg. F. | 17 to 21 deg. F. | 25 to 31 deg. F. |
| Wind Direction: | Southwest | Southwest | Southwest |
| Wind Speed: | 17G31 | 16G29 | 17G30 |
| Snowfall: | 0" in. | 0" in. | 1" in. |
| Snow Line: | 2500' | 2500' | 3500' |
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.
