Regions
Northwest Coastal.
Uncertainty about expected storm snow amounts means avalanche activity could be larger and run farther than one might normally expect. Use increased caution if more than 30 cm of new snow accumulates.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
SATURDAY NIGHT: No precipitation. Calm winds.SUNDAY: Snow developing with 15 to 30 cm new snow. Freezing level around 500 m. Winds increasing to moderate or strong from the south.MONDAY: Around 10 to 20 cm new snow. Freezing level around 800 m. Winds light to moderate from the southwest.TUESDAY: Cloudy with sunny periods. Freezing level around 800 m. Light westerly winds.
Avalanche Summary
No new avalanches reported Friday. Two small (size 1.5) slab avalanches were triggered by separate ski groups on Thursday, one on a northwest aspect at 1250 m and one on a northwest aspect at 1500 m. Both are thought to have released on the mid-february weak layer buried 30-50 cm below the surface.
Snowpack Summary
Scoured surfaces and aging hard wind slabs can be found on all aspects in exposed terrain after a prolonged period of outflow winds. South facing slopes have sun crusts on the surface.The upper- and mid-pack is weakening with continued cold temperatures so there are widespread areas with soft faceted snow, and possibly surface hoar. This sugar soft snow has been reactive in some snowpack tests and there have been some small slab avalanches noted on this layer. There is potential for this layer to become a larger problem with additional new snow.The lower snowpack is generally considered strong.
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.