Observers reported numerous natural and triggerd avalanches yesterday. New snow and strong winds will continue to create very dangerous avalanche conditions. Travel in or below avalanche terrain is not recommended, particularly at upper elevations. At lower elevations, stick to lower angled terrain and avoid exposure to avalanche terrain overhead. Collapses, shooting cracks, and recent natural avalanches are red flags. Blowing snow will point to the slopes where the most sensitive slabs are still forming.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Dense slabs of new snow will become larger and more sensitive as you gain elevation. Expect slabs to be stiffer and more dangerous in exposed, leeward terrain. Widespread human triggered and natural avalanches were reported yesterday. Today, very dangerous avalanche conditions and natural avalanches will continue, especially at upper elevations as westerly winds increase. Avoid slopes steeper than about 35 degrees as you gain elevation. Be wary of undercutting avalanche terrain. Shooting cracks, blowing snow, and natural avalanches are red flags directing you step back. Be wary of traveling in tracks and runouts of avalanche paths that extend below treeline. Isolated, steep, lower elevation slopes – like road cuts – may have enough snow to slide.
Very weak layers of surface hoar and sugary facets have been buried under soft snow since New Years, now several feet thick. Riders yesterday triggered avalanches remotely or from below in the Swan and Whitefish Ranges highlighting the unpredictable nature of this problem. The weakest and most developed layers were seen in Glacier National Park prior to this storm. Crusts below them will act as sliding surfaces. Avoid exposing yourself to slopes connected to avalanche terrain overhead and give yourself a wide margin for error to handle their erratic behavior. Whumpfing noises and shooting cracks are like alarm bells telling you to stick to lower angled, simple terrain. Smaller storm slab avalanches may suddenly overload buried weak layers resulting in larger, dangerous slides.
It finally feels like old man winter may have woken up, and he is not happy about it. Since the storm began on Monday, northwest Montana has picked up significant new snowfall. Storm totals thus far range between 2.1” of new water at the Stahl and Flattop weather stations and 3.3” in Noisy Basin. Over 1.5” of that new SWE fell in the last 24 hours.
Snowpacks hate rapid change, and avalanche activity yesterday shows how grumpy the mountains have become. Riders across the region triggered soft slabs, like these, breaking within the new storm snow yesterday. In John F. Stevens Canyon and Lost Johnny Canyon, large natural avalanches ran down to lower elevations. One buried the road and covered snowmobilers' tracks from the day.
Riders triggered some slabs remotely or from below yesterday, highlighting the danger of buried weak layers. Even where avalanches did not fail, whumpfing collapses, shooting cracks, and propagating test results confirmed that layers buried around the holidays are not adjusting well to the new loading. These layers of buried facets and surface hoar are capable of propagating widely. They can triggered from a distance making them dangerous eggshells under your weight.
Today, dangerous conditions will persist. More snow will fall through today with winds capable of transporting it onto leeward slopes. In higher elevation terrain of the Flathead Range and closer to the Continental Divide, strong to extreme winds will make the situation very dangerous. Exercise self-discipline and keep your terrain choices conservative; natural avalanche activity will continue on wind loaded terrain. The good news is that as old man winter has dropped the freezing levels, and more lower elevation terrain is covered in snow. Keep an eye out even below 5,000’ for isolated steep slopes, like road cuts, where there is enough snow to slide. And have a good understanding of what is above you. Avalanches that start high on a slope may run down to lower elevations.
A Pacific cold front will move through the region this morning causing widespread snow and strong westerly winds near the Divide. Temperatures will drop as the front passes. A stronger disturbance may bring moderate to heavy snowfall Firday.
| Wednesday | Wednesday Night | Thursday | |
|---|---|---|---|
| Cloud Cover: | Overcast | Mostly Cloudy | Mostly Cloudy |
| Temperatures: | 24 to 30 deg. F. | 7 to 11 deg. F. | 11 to 17 deg. F. |
| Wind Direction: | Southwest | Southwest | Northwest |
| Wind Speed: | 20 to 30, G50 | 16G37 | 11G24 |
| Snowfall: | 4" to 5" in. | 1" to 2" in. | 1" in. |
| Snow Line: | 2500' | 500' | 0' |
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.
