New snow and wind have created touchy storm slabs above the crust that formed with recent warm temperatures. These slabs will continue to build and hazard rise as the next storm system arrives on Wednesday.
Confidence
Moderate - Freezing levels are uncertain
Weather Forecast
TUESDAY NIGHT: Flurries. Accumulation 2-5 cm. Ridge wind moderate, south. Temperature -2. Freezing level 1000 m.WEDNESDAY: Cloudy, snow. Accumulation 30-40 cm. Ridge wind strong to extreme, south. Temperature near 0. Freezing level rising to 1600 m.THURSDAY: Cloudy, snow. Accumulation 15-25 cm. Ridge wind strong, southwest. Temperature near 0. Freezing level 1000 m.FRIDAY: Cloudy, snow. Accumulation 5-15 cm. Ridge wind moderate, south. Temperature -3. Freezing level 900 m.
Avalanche Summary
Tuesday, explosive control work and ski cutting produced numerous size 1-1.5 storm slab releases on leeward aspects at treeline and into the alpine, running on the January 15th crust. Expect this activity to increase as more snow and strong winds forecasted for Wednesday and Thursday.Warm alpine temperatures on Sunday produced numerous naturally triggered loose wet and wet slab avalanches mostly in the size 1-1.5 range, and a few up to size 2 on solar aspects.
Snowpack Summary
Above 1600 m elevation, 20-40 cm of new snow overlies the January 15th crust which exists on all aspects and elevations. This crust is thin on northerly aspects and up to 3 cm thick on solar aspects. Below this crust 30-40 cm of moist, well settled snow overlies the January 6th crust which is now buried 40-80 cm below the surface and exists up to about 2000m. Beneath the January 6 crust, the lower snowpack is generally strong and well settled.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.