Warm temperatures and sunny skies forecast for the next few days will have a significant weakening effect on the snowpack. If solar radiation is particularly strong, the avalanche danger could rise to HIGH.
Summary
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Thursday
Weather Forecast
Generally clear skies are expected for the forecast period as a ridge of high pressure becomes established over much of the province. Winds are forecast to be light to moderate from the northwest becoming southwesterly on Saturday. Daytime alpine temperatures are expected to hover between 0.0 and +5.0.
Avalanche Summary
Several natural storm slab avalanches to size 3 were reported in the region on Tuesday, most occurring in alpine terrain on various aspects. I would expect avalanche occurrences to include loose wet activity with the potential for deeper slab activity with forecast warming on Thursday
Snowpack Summary
Parts of the forecast area have received up to 90cm of storm snow which has been blown into dense windslabs in exposed areas. The new snow overlies a variety of old surfaces, the most reactive of which appears to be the Jan 8th surface hoar. There are reports of "sudden" test results on this layer, now buried anywhere from 55cm to 90cm below the surface. There are 2 other layers of note which professionals are keeping a close eye on: The late-November persistent weak layer consists of a sun crust on steep south facing slopes and surface hoar in sheltered areas and may sit well over 200cm below the surface. At the base of the snowpack you may also find the October persistent weak layer which consists of facets sitting on a crust. This layer is predominantly found on northerly aspects at tree line and in the alpine. The depth of both these layers makes directly triggering an avalanche on them unlikely (maybe a heavy load on a thin spot in steep terrain), but the consequences would be large and destructive.
jlammers,
Avalanche Canada
