Avalanche Forecast
Regions: Lizard-Flathead.
Another wet storm will increase avalanche danger through the day Wednesday. Avoid all avalanche terrain including low elevation runout zones during this period of heavy loading from new snow, wind, and rain.
Confidence
High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
Another wet one.
Tuesday night: Flurries starting 5-10 cm. Strong southwest wind. Freezing level rising 1800 to 2500 m by morning.
Wednesday: Wet snow and rain, 20-40 mm. Strong to extreme southwest wind. Freezing level 2500 m.
Thursday: 10-20 mm rain turning to snow overnight then clearing. Moderate southwest wind. Freezing level dropping 2000 to 1700 m.
Friday: Mix of sun and cloud. Light winds. Freezing level valley bottom.
Avalanche Summary
No new avalanches were reported on Tuesday. A natural size 2 was observed in the alpine on Monday. Several natural storm slab avalanches were observed in the alpine on Sunday, a few notably stepping down to deeper layers (suspect the mid November crust).
A natural avalanche cycle occurred overnight Thursday-Friday, large storm slab avalanches (size 2-2.5) in alpine and upper treeline features were reported Friday morning. Through the day, explosives triggered large (size 2) storm slab avalanches.
Snowpack Summary
Overnight snow turning to rain soaks the dense upper snowpack at most elevations. Wet snow accumulations may form heavy storm slabs in the high alpine.
Below 40 cm of recent storm snow lies a thick mid-November rain crust which has been the suspected bed surface of a few recent step-down avalanches. Moist snow is still found below the crust and to the ground.
Snowpack depths range from 40-70 cm at treeline elevations. Expect to find a deeper snowpack at higher elevations and in wind-loaded areas. Snowpack depths decrease rapidly below 1500 m.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Avoid areas with overhead hazard.
- Avoid lingering or regrouping in runout zones.
Avalanche Problems
Storm Slabs
Heavy, wet snow in the high alpine will build storm slabs through the day Wednesday. Size and sensitivity to triggering will increase as the storm progresses.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Very Likely - Almost Certain
Expected Size: 1 - 2.5
Loose Wet
Heavy rain soaks the snowpack treeline and below. The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
Hazard below treeline reflects the potential for avalanches from above to reach low elevation runout zones.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Very Likely - Almost Certain
Expected Size: 1 - 2