Regions
Northwest Coastal.
The December week may still be reactive to moderate loads. Continue to make conservative choices as the new snow with wind comes into the region.
Confidence
Good - Intensity of incoming weather systems is uncertain
Weather Forecast
A weak upper level trough will arrive on the coast on Monday bringing flurries to the region. As the trough moves inland on Tuesday, the North coast may see up to 25 cm of snow at higher elevations, and the possibility of rain up to 1500m. Winds will be light to moderate from the south throughout the forecast period. Wednesday will see a bit of clearing before the next pulse of moisture arrives later in the day. Freezing levels around 500m until Wednesday, when they will spike to 2000m before coming back down on Thursday.
Avalanche Summary
No avalanches reported yesterday.
Snowpack Summary
Strong winds have redistributed the recent storm snow, and rain in some areas has produced a surface crust layer that will be of concern with future snow loading. A buried surface hoar layer in the mid-snowpack is still on the radar in some northern sections , and the mid December crust can still be found in the middle of the snowpack. This layer has been reported to be sandwiched between facets and surface hoar in some places. The November crust near the bottom of the snowpack is generally well bonded but may still be reactive in areas with shallow snowpack.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.