Snowfall overnight formed fresh, shallow storm slabs overlapping with thicker slabs from earlier this week. Thin wind slabs may develop on atypical slopes from northeast winds. Evaluate snow totals, wind transport, and look for surface cracks as a sign of instability.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Light snowfall began overnight with Noisy Basin reporting up to 7”/ 0.7” SWE. Today’s snowfall may form shallow storm slabs at mid and upper elevations. These slabs are overlapping with thicker slabs from earlier this week. Surface instabilities can be evaluated by monitoring snow totals and using hand pits to evaluate bonding with the old snow surface. Dig down 1 to 2 feet to evaluate bonding to buried crusts. Watch out for steep, unsupported slopes especially in wind-exposed terrain. Wind-sheltered slopes less than 35 degrees offer the safest riding conditions.
Observations yesterday found thin, newly formed wind slabs reactive to the weight of a skier at mid and upper elevations. These slabs were found on steep, cross-loaded terrain. Additional snow and northeast winds today may develop thin wind slabs on atypical slopes. Monitor snow totals, wind transport, and anticipate these slabs to become thicker and more widespread by this afternoon. Approach lens-shaped pillows with caution and look for cracks in the surface snow as a sign of instability.
The cold and unsettled weather pattern that brought up to 2 feet of snow earlier this week continues today. Light snowfall began overnight as a cold front pushed into northwest Montana over the Continental Divide colliding with warm, moist air on a west flow. Noisy Basin is reporting up to 7”/ 0.7” SWE with the rest of the forecast area reporting up to 1” of new snow. Continued snowfall today may develop shallow surface instabilities. Yesterday, Zach found storm snow from earlier this week more stubborn to human triggers and noted a lot of settlement and slab consolidation. Despite no observable signs of instability in old storm slabs, additional snowfall is adding stress onto a slab that produced natural and skier triggered avalanches this week. In addition to monitoring new snow instabilities, dig down 1 to 2 feet to evaluate bonding to buried crusts.
Today’s snowfall is accompanied by light to moderate northeast winds. This may form thin wind slabs on atypical, leeward slopes. Monitor wind transport at mid and upper elevations and anticipate wind slabs to expand in distribution form ones formed yesterday. The abundance of loose snow from earlier this week will be easy to form deeper drifts with a slight increase in wind speeds or strong gusts. Cracking in the surface snow is a sign of instability and approach lens-shaped pillows with caution. A small slide around trees and cliffs can have a bad outcome.
A cold front moved into northwest Montana overnight. Light snowfall began along with a lowering of mountain temps. The front is forecasted to make a significant push westward tonight with an increase in snowfall amounts. The cold front boundary is forecasted to stall out over northwest Montana over the next 36 hours with continued unsettled weather and light accumulations during each 12-hour period.
| Thursday | Thursday Night | Friday | |
|---|---|---|---|
| Cloud Cover: | Snow | Snow | Snow showers |
| Temperatures: | 25 to 30 deg. F. | 8 to 13 deg. F. | 26 to 32 deg. F. |
| Wind Direction: | NE | E-NE | E-SE |
| Wind Speed: | 5 to 10 mph, gusts 15 mph | 10 to 15 mph, gusts 25 mph | 5 to 10 mph, gusts 15 mph |
| Snowfall: | 1 to 2 in. | 1 to 3 in. | 0 to 1 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.
