Non-scheduled update: Heavy, wet snow (4-10 inches) and rain fell across the advisory area with the Swan Range picking up the most. This new snow may not bond well to the underlying surface. Storm and wind slabs coud be easily triggered and large enough to knock you around or bury you. Deeper wet slabs are still possible due to ample rain yesterday. Carefully assess how the new snow reacts particularly on slopes steeper than 35 degrees.
?
Above 6500 ft.
?
5000-6500 ft.
?
3500-5000 ft.
Non-scheduled update: Noisy Basin SNOTEL in the Swan Range reports over 2.5 inches of precipitation since yesterday morning! Most of this fell as rain yesterday and turned to snow last night. As of 8:00 a.m. the Swan Range picked up 10 inches with more likely above 6000 feet. The new snow is going to be wet and heavy and I suspect you could trigger both storm slabs and heavy wet, loose avalanches today. Lesser amounts of rain and snow fell in the Whitefish and Flathead Ranges and the hazard may be lower in those ranges. Big Mountain Summit station reports about 5 inches of new snow and a temperature of 26º F. (0.5 inches of precipitation) with rain yesterday turning to snow overnight. Winds shifted back to the southwest so expect wind slabs at the upper elevations on leeward slopes.
Careful snowpack evaluation and conservative decision making is essential today. New snow is nice to see (even if it is heavy) after a rather prolonged dry spell and then a lot of rain. Ease into terrain today. Even small wet snow avalanches in the wrong place (like a terrain trap) can be deadly.
After the inundation with rain (over four inches in some locations) on Sunday into Monday and now yesterday (over 2 inches in the Swan Range), the snowpack below the new snow is wet and moist. When stepping off of your sled or skis, you can still sink through to your knees. Allow the snowpack time to recover from this heavy rain event and use cautious route-finding techniques before committing to a slope. It may still be possible to trigger a slab due to free water moving deeper through the snowpack especially in areas where there was a light or no refreeze. Wet snow avalanches are notoriously difficult to predict and if you are still sinking above your boot top in snow (even with new snow above) it is time to head for less steep slopes.
The next regularly scheduled advisory will be issued tomorrow, March 19.
| 0600 temperature: | 20-31 deg. F. |
| Max. temperature in the last 24 hours: | 26-33 deg. F. |
| Average wind direction during the last 24 hours: | North to Southwest |
| Average wind speed during the last 24 hours: | 4-12 mph |
| Maximum wind gust in the last 24 hours: | 18-24 mph |
| New snowfall in the last 24 hours: | 4-10 inches |
| Total snow depth: | 59-95 inches |
| Wednesday | Wednesday Night | Thursday | |
|---|---|---|---|
| Cloud Cover: | Tapering precipitation by later today. Fluctuating snow levels. | Drying and ridge building. | Drying and ridge building. |
| Temperatures: | 37-48 deg. F. | 28-33 deg. F. | 41-52 deg. F. |
| Wind Direction: | Southwest | Southwest | Southwest |
| Wind Speed: | 5-10 mph with gust to 20 mph. | 5-10 mph with gust to 20 mph. | 5-10 mph with gust to 20 mph. |
| Snowfall: | 1-3 in. | 0 in. | 0 in. |
| Snow Line: |
This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires at midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.
