Regions
Northwest Coastal.
Significant snow and rain will likely result in a large and destructive avalanche cycle.
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Synopsis: A return to a heavy precipitation pattern is expected as the North Coast feels the brunt of a strong Pacific frontal system. Tonight and Wednesday: Heavy snow turning to rain: 30 to 40cm overnight with another 20 to 30cm Wednesday. Freezing levels: 800m rising to 150m Wednesday morning. Strong to extreme ridge top winds from the south.Thursday: Heavy precipitation. Freezing levels: between 1500m to 2500m. Strong to extreme ridgetop winds from the south.Friday: Periods of snow: Freezing levels falling. Winds forecast to diminish from the southwest.Special Notice: Our radar has just picked-up what appears to be a flying sleigh. Our forecasters believe the sleigh belongs to Santa as it is being pulled by at least 8 reindeer. The sleigh is now in the far north of the province at the 2000m elevation and is currently headed south. More information will be posted as it becomes available.
Avalanche Summary
The peak period of natural activity for the last storm cycle seems to have passed although explosive control continues to produce size 2 avalanche in the storm snow.
Snowpack Summary
The weekends storm brought between 50 to 90cm to the region. With lots of snow available for transport strong westerly winds have likely loaded lee features at upper elevations. In many places these winds slabs sit on top of touchy surface hoar from December 22.. The mid pack features several persistent weak layers that at this point have likely gained strength. The most noteworthy of theses may be the early December surface hoar and crust found in the top 100cm in areas with a shallower snowpack where it could still be a player. Below this the mid pack is composed of deteriorating layers of old facets and crusts. A significant basal facet and crust combo lingers near the ground and is most prevalent on NW - E facing aspects at the upper TL and alpine elevations.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.