Regions
Northwest Coastal.
Confidence
Fair - Due to limited field observations for the entire period
Weather Forecast
A zonal flow is forecast through Wednesday with moderate to strong westerly winds and short-lived disturbances delivering 5 to 10 cm of snow each day, especially on the west (upslope) side of the ranges. Freezing level should remain near valley bottoms. Heavier precipitation is expected to start Wednesday evening when the next major system hits the coast which could bring another 30+cm by Thursday evening with freezing levels as high as 1200m.
Avalanche Summary
Reports are coming in about a widespread natural avalanche cycle that occurred on Saturday with avalanches up to Size 3.5 running almost full-path on all aspects and elevations. Natural and slope-cut activity continued on Sunday with avalanches up to Size 2 running within the upper storm snow on steep unsupported features and gullies at treeline and below. Explosive control on Sunday produced avalanches up to Size 3.5 all running on weaknesses within the recent storm snow.
Snowpack Summary
Total snowpack depths are well above average for this time of year and it won't stop snowing!Recent warm temperatures and upside-down storms created a touchy surface slab. Other weaknesses exist within and under the 150+cm of recent storm snow, but things seem so be settling rapidly. Strong winds associated with recent storms mean wind slabs on lee and cross-loaded terrain. Most snowpack concerns are limited to the surface layers, however large triggers such as cornice falls and smaller avalanche stepping-down could reawaken deeper persistent weaknesses.
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.
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.