Regions
Northwest Coastal.
The recent storm was more intense than anticipated. Touchy, dangerous conditions will linger. Be cautious if you are venturing into the backcountry at this time.
Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Synopsis: A short-lived ridge builds for Wednesday before a series of generally light precipitation bands move through Thursday and Friday.Wednesday: Mostly dry. Northwest winds around 40 km/h at ridgetop. Freezing level around 400m.Thursday: Light snowfall, 2-5cm. Southwest winds to 50 km/h at ridgetop. Freezing level 800m in the afternoon.Friday: Light or locally moderate snowfall, 5-10cm. Perhaps a little more towards the coast. Extreme southwest winds, gusting up to 90km/h at ridgetop.
Avalanche Summary
A widespread avalanche cycle up to size 3 was reported in response to the recent intense storm. The most activity appears to have been close to Terrace.
Snowpack Summary
A big dump of snow brought up to 80cm and an average of about 40cm new to the region on Tuesday. Strong winds have blown the new snow into wind slabs in exposed lee areas. The new snow sits on above previous wind slabs on shady slopes in the alpine and at treeline, and a rain/sun crust at lower elevations/solar aspects, respectively. Deeper buried crusts exist within the snowpack, but are reported to have bonded well. I imagine that after the most recent avalanche cycle, these will be difficult or near impossible to trigger, except with very big loads, such as a cornice fall. The mid and lower snowpack layers are generally 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.
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.