Regions
Northwest Coastal.
Careful route selection is critical during this storm cycle.
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
Moderate to heavy precipitation will arrive on the coast today (Wednesday) through Friday bringing as much as 90mm through the forecast period. Saturday should start a clearing trend. Strong winds will accompany the incoming precipitation . Freezing levels will stay around the 1500M mark , but drop to around 500m on Saturday.
Avalanche Summary
There has been little avalanche activity reported given the amount of new snow from the last storm. Size 1 skier triggered wind slabs have been reported in high elevation lee terrain. Incoming precipitation will change things up and may spark another round of natural storm slab activity.
Snowpack Summary
The previous storm accompanied by strong southwest winds has built dense slabs on exposed lee features. Incoming precipitation will add additional load to the storm slab. Below this there are a variety of interfaces including old hard wind slabs, hard crusts, surface hoar, and/or surface facets. Reports suggest a reasonable bonds at these interfaces, although we should remain cautious of steeper, high-consequence slopes, as a release on these recently buried surfaces could be large and destructive . At the base of the snowpack, weak facets may be found, particularly on shallow alpine slopes in the north of the region. Cornices are becoming large and potentially unstable.
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.