Heavy precipitation and strong winds have created reactive storm slabs at higher elevations. New snow needs time to stabilize.
Weather Forecast
Only trace amounts of precipitation for today as an upper ridge of high pressure builds over the province. Expect moderate SE winds, freezing levels to 1700m and alpine high of -1. Warm and wet southwesterly flow resumes early Monday morning with the arrival of a pacific front. Expect 7cm of accumulation above 1800m and rain below.
Snowpack Summary
Intense rain in the last three days has left the upper snowpack moist or wet to around 2100m. Above 1900m there is 70-80cm of heavy storm snow. The Jan 30 surface hoar/crust layer, up to 2200m, is down 50-90cm and depth will depend on elevation. Jan 15 surface hoar layer is down 100-150cm and was reactive in artillery highway avalanche control.
Avalanche Summary
Observed several new large natural avalanches yesterday in the Highway Corridor. Most of the new slides began dry and ended moist, terminating farther than previous artillery triggered avalanches and in some cases gouging into existing debris.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.