Regions
Northwest Coastal.
The overnight storm will quickly raise the hazard for Saturday. Give the new snow time to stabilize and stick to simple terrain.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
The weak storm system exits the region on Saturday morning and will be replaced by a ridge of high pressure. This ridge is expected to persist for several days. Friday night's storm is currently forecast to yield 20-30mm of precipitation for much of the region. On Saturday, snow should taper off in the morning, brief periods of sun are possible, freezing levels around 700m, and light-to-moderate northerly alpine winds. Sunday should be mostly clear and dry with freezing levels dropping to valley bottom and moderate NE alpine winds. Monday should be pretty much the same with colder temperatures.
Avalanche Summary
No new reports were received on Thursday or by publish-time on Friday. On Wednesday we received reports of natural avalanches up to size 2 from steep terrain features around treeline elevation. Explosive control on Wednesday produced storm slab and wind slabs up to size 2.5. Most of the activity was on north through east aspects. Natural activity is expected on Saturday.
Snowpack Summary
The new snow sits on a well-settled snowpack. Between Dec 18-24 over 1m of snow fell in many parts of the region. The instabilities associated these storms appear to have healed but there may be lingering concerns such as old wind slabs or cornices. The new storm snow will come with strong W-NW winds some new wind slab formation can be expected. The mid and lower snowpack contains several old crust layers but these layers appear to be well bonded.
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.