Regions
South Coast Inland.
In the south of the region, widespread storm slabs are possible and the alpine danger rating is High. In the north of the region, wind slabs are expected to be the primary concern and the alpine danger ratings is expected to Considerable.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
The last major low pressure system is expected to bring periods of heavy snowfall to the region on Thursday. 10-15 cm is expected Wednesday overnight and 20-40 cm is expected on Thursday with the deepest amounts in the south of the region. Alpine wind is forecast to be strong from the southwest on Thursday and freezing levels are expected to reach around 800 m elevation. Mostly dry and sunny conditions are expected for Friday with light alpine wind and freezing levels around 600 m. A weak storm pulse is forecast to bring around 5 cm of snow on Saturday with strong alpine wind from the northwest.
Avalanche Summary
No new avalanches have been reported from the region in several days. On Thursday, wind slab avalanches are expected throughout the region. In the south of the region, a more widespread storm slab problem is expected.
Snowpack Summary
In the Coquihalla area, around 50 cm of new snow has accumulated since Monday. In the Duffey Lake area, around 20 cm of new snow has accumulated since Monday. This new snow sits over a variable interface which consists of wind affected surfaces, faceted (sugary) snow, or surface hoar. The surface hoar has been observed up to 5 mm in size in the Duffey Lake area. A thin sun crust may also exist in the upper snowpack and was reported around Coquihalla area over the weekend. Recently strong southerly winds have formed new wind slabs in leeward and cross loaded features in wind exposed terrain. The mid and lower snowpack are generally expected to be well settled and stable.
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.