Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2.5–3.5
Multiple weak layers, present roughly 1 - 2 m deep, continue to produce surprising avalanches . Avalanches failing on these layers have been large and destructive.
Avoid avalanche terrain
Strong wind, heavy precipitation and high freezing levels will likely result in natural avalanches at all elevations, they could fail on deep weak layers and run far
Multiple weak layers, present roughly 1 - 2 m deep, continue to produce surprising avalanches . Avalanches failing on these layers have been large and destructive.
Wet loose avalanches will increase in size and likelihood where precipitation falls as rain.
Natural storm slabs could initiate at high elevations and run below treeline. These large avalanches could also step down to buried weak layers, resulting in very large avalanches.
Over the past 3 days several size 3 and 3.5 persistent slab avalanches were reported. These avalanches were triggered naturally, remotely, and by falling cornices. They occurred on easterly aspects at treeline and above.
Numerous storm and wind slabs were also reported.
By Tuesday morning precipitation will likely switch from snow to rain, except in the alpine. The upper snowpack is expected to become saturated from the rain below treeline. In the alpine, strong to extreme southwest wind will form deep deposits on north and east aspects.
Three concerning weak layers of surface hoar, facets and/or crust formed in January and February are in the mid-snowpack, 1 to 2 m deep.
The lower snowpack is well settled and bonded.
Monday Night
Cloudy. 10 to 25 cm of snow. 60 km/h southwest ridgetop wind. Treeline temperature -1°C.
Tuesday
Cloudy. 5 to 15 mm of rain at treeline, snow in the alpine. 50 km/h southwest ridgetop wind. Treeline temperature 2°C. Freezing level 2500 m.
Wednesday
Cloudy. 15 to 25 cm of snow at treeline, rain below. 60 km/h southwest ridgetop wind. Treeline temperature 1 °C. Freezing level 2300 m.
Thursday
Cloudy. 10 to 25 cm of snow at treeline, rain below. 60 km/h southwest ridgetop wind. Treeline temperature 0°C. Freezing level 2100 m.
More details can be found in the Mountain Weather Forecast.