Danger will increase throughout the day on Wednesday as an intense storm builds fresh storm slabs.
Confidence
Moderate - Timing of incoming weather systems is uncertain on Wednesday
Weather Forecast
TUESDAY NIGHT: Increasing cloud, light wind from the west, alpine temperatures drop to -4 C, freezing level around 800 m.WEDNESDAY: Stormy weather starting in the afternoon with 10-20 cm of snow by the afternoon and freezing level around 800 m, then things really intensify overnight with another 30-60 cm as the freezing level rises to 1400 m and the snow transitions to rain, strong wind from the southwest throughout the storm.THURSDAY: Heavy rain (possibly another 40-100 mm), freezing level up to 1800-2000 m, extreme wind from the southwest.FRIDAY: Another 15-20 mm of rain as the freezing level drops to 1300 m, then gradual clearing in the afternoon.
Avalanche Summary
No new avalanches have been reported in the past few days.
Snowpack Summary
Fresh storm slabs will build on Wednesday before the precipitation transitions to rain on Thursday. The new snow is falling on a widespread crust that extends at least to 1500 m elevation. At the highest elevations, an additional 40-60 cm of recent snow may not be bonding well to underlying surfaces. This is particularly the case in the north of the region near Squamish, where the snow may be sitting on a weak layer of feathery surface hoar. The lower snowpack is 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.