Strong southerly wind, continued precipitation and lowering freezing levels are expected to drive fresh storm slab development through Friday. Wind slabs are likely to be found in unusual locations, welcome back to winter!
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
A rather complex weather pattern continues to deliver precipitation to the South Coast. Lower freezing levels Thursday night should allow for snow at lower elevations. Precipitation is expected to diminish Friday night with a brief window of clearing Saturday.THURSDAY NIGHT: Freezing level holding at 500 m, moderate to strong south/southwest wind, 10 to 15 more mm of precipitation. FRIDAY: Broken cloud cover, freezing level holding near 500 m, moderate southwest wind, 15 to 20 mm of precipitation expected.SATURDAY: A few clouds, freezing level beginning at 500 m rising to 1000 m, light south/southwest wind, no significant precipitation expected. SUNDAY: Scattered cloud cover, freezing level holding at 700 m, light to moderate west/southwest wind, a few mm of precipitation possible.
Avalanche Summary
New rain, snow and wind Wednesday night into Thursday likely initiated fresh avalanche activity that was probably most pronounced in higher elevation terrain.
Snowpack Summary
Around 30 mm of rain transitioning to up to 20 cm of snow has fallen as of Thursday afternoon with wind out of the southeast. This snow sits on a mixture of weak grains including a slippery crust that is present at all elevations on solar aspects and low elevation polar aspects. On polar aspects at and above treeline the new storm snow may be burying facets and surface hoar. The storms transition from warm to cold should be great for our snowpack in the long term, but fresh touchy storm slabs are expected to continue to build Thursday night and Friday. Below any recent snow accumulations, the overall snowpack is well settled and strong.
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.