Avalanche Forecast
Regions: Lizard-Flathead.
There is uncertainty with snowfall amounts Monday night through Tuesday. Avalanche danger is expected to rise as snow accumulates through the day on Tuesday.
Confidence
Moderate - Forecast precipitation (either snow or rain) amounts are uncertain.
Weather Forecast
Monday Night: Snow, accumulation 10-20 cm. Light to moderate west winds. Alpine temperatures around -5 C. Freezing level 700 m
Tuesday: Snow, accumulation 20-30 cm with another 15-25 cm through Tuesday night. Moderate southwest winds. Alpine temperatures around -3 C. Freezing level 1300 m.
Wednesday: Scattered flurries, accumulation 5-10 cm. Moderate southwest winds. Alpine temperatures around -3 C, freezing level 1200 m.
Thursday: Mainly cloudy. Light northwest winds. Alpine temperatures around -10 C. Freezing level valley bottom.
Avalanche Summary
Expect to see an increase in storm slab activity as the wind picks up and new snow accumulates on Tuesday.
This MIN from Harvey on Saturday includes a photo of a size 1 wind slab avalanche in the lee of a ridge feature below treeline, and describes signs of instability like shooting cracks.
Snowpack Summary
20-30 cm of new snow has now obscured widespread wind affected snow that extended well below tree line. Recent Cornice growth in the alpine has been notable.
Several crusts layers have formed in the mid to upper snowpack as a result of recent warming and rain events. As these crusts become buried deeper, they have the potential to turn into a persistent slab problem. We'll be keeping an eye on them going forward.
The lower snowpack consists of weak faceted snow and decomposing crusts but has not been an active avalanche problem recently.
Terrain and Travel
- Watch for fresh storm slabs building throughout the day.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
Avalanche Problems
Storm Slabs
Snow accumulating overnight Monday and through the day Tuesday combined with moderate southwest wind will promote storm slab formation. Expect slabs to become more reactive through the day. The new snow has also obscured widespread windslabs (including open areas below treeline) that formed over the weekend.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2