Confidence
Poor - Timing of incoming weather is uncertain
Weather Forecast
Wednesday night and Thursday: Another system arrives bringing 20-35cm of snow. The freezing level should start at around 1400m and lower to 1000m on Thursday. Winds are strong from the W-SW. Thursday afternoon should be a little drier before another system arrives overnight. Friday: 15-25cm of snow. Continued strong SW winds. Freezing level 1000-1200m. Saturday: Drier for the first half of the day as a brief ridge of high pressure builds, but should see some precipitation in the afternoon as another frontal system is on the way. Freezing level starting at 600-800m, rising with the warm front. Low confidence for Saturday.
Avalanche Summary
Numerous Size 1-2 slab avalanches (both natural and human triggered) have been reported in the past 48 hours. There is one new report of a Size 2 accidentally triggered avalanche on Paul Ridge (Garibaldi Park) on Wednesday. Luckily no one was involved. Expect the size and likelihood of avalanches to increase through the forecast period.
Snowpack Summary
25-50cm of snow fell last night bringing the total snowfall in the past week to 80-150cm. Wind slabs continue to grow in exposed NW-E facing slopes, probably as deep as 100cm in some areas. A weak rain crust is found below the new snow up to treeline elevations. This crust may sit on top of buried surface hoar and/or facets may persist 10-20cm below. One observer near Whistler reported whumpfing on a buried surface hoar layer in low-angle terrain below treeline. Watch this layer as it gets more load and a thick cohesive slab develops, particularly below treeline where the buried surface hoar would be especially large. A strong mid pack overlies basal facets that have also gained considerable strength. On average the snowpack is around 200cm deep near treeline.
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.
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.