Avalanche Forecast
Regions: Flathead, Lizard, Lizard-Flathead.
Avoid avalanche terrain during the storm, it will be very dangerous.
Confidence
High
Avalanche Summary
A natural avalanche cycle will occur on Wednesday.
A few small (size 1) slab avalanches were reported on Monday and over the weekend, along with other signs of instability indicating the surface hoar layer could be reactive when buried beneath a slab.
Snowpack Summary
15 to 25 cm of snow overnight and another 15 to 25 cm during the day will cause short-lived instabilities within the storm snow. Expect deep wind drifts at higher elevations.
A surface hoar layer, 20 to 40 cm deep prior to the storm, will be 50 to 80 cm deep by Wednesday afternoon. While its distribution is uncertain, it is expected to become reactive as a slab forms above it.
Treeline snow depths before the storm ranged from 100 to 150 cm.
Weather Summary
Tuesday Night
Cloudy with 15 to 25 cm of snow. 40 to 60 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Wednesday
Cloudy with 15 to 25 cm of snow. 60 to 80 km/h southwest ridgetop wind. Treeline temperature -2 °C.
Thursday
Mostly sunny. 20 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Friday
Sunny. 30 km/h southwest ridgetop wind. Treeline temperature +2 °C. Freezing level climbing to 3000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.
- Storm slab size and sensitivity to triggering will likely increase through the day.
Avalanche Problems
Storm Slabs
Heavy snowfall and wind will form large storm slabs Tuesday night into Wednesday. A weak surface hoar layer beneath the slabs could make them very touchy.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2.5