Winter is set to return with a storm system expected to arrive late Saturday and into Sunday. The storm snow may be easily triggered, especially in "fat" areas that have seen additional loading from wind.
Confidence
Moderate - Freezing levels are uncertain on Sunday
Weather Forecast
SATURDAY: Flurries. Accumulation 5 cm. Ridge wind light from the west. Temperature near 0. Freezing level 800 m.SUNDAY: Snow. Accumulation 15-20 cm. Ridge wind moderate from the southwest. Temperature near 0. Freezing level 1200 m.MONDAY: Flurries. Accumulation 5-10 cm. Ridge wind light from the west. Temperature near 0. Freezing level 800 m.-
Avalanche Summary
No new avalanches have been observed during the past week however, some rather large blocks of snow were observed to topple over from the base of a steep, rocky outcrop depositing a 10 m wide debris pile across a snowshoe trail on Monday.
Snowpack Summary
Beneath the new storm snow lies a widespread melt-freeze crust on all aspects and elevations. On north aspects the crust is likely quite hard while on southerly aspects and at lower elevations the crust may still be moist. Below the snow surface, the upper snowpack is well-settled an sits on the late-November rain crust. This crust is now buried approximately 120 cm at 1300m elevation, and is up to 30 cm thick. Beneath the November crust, the lower snowpack is wet to ground. Below treeline the snow pack is thin and there are many early season hazards. Snowpack depths range from 30 cm at 800 m elevation to 180 cm at 1220 m.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.