Regions
Northwest Coastal.
Stormy weather will maintain elevated avalanche danger this week.
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Synopsis: It looks like we’re in for a wet and stormy week! Precipitation amounts: Tonight and Weds = 20-40 mm, Thursday = 20-30 mm, Friday = possible even heavier amounts. Freezing levels should rise to 1500 m on Wednesday and gradually climb closer to 2000 m by Friday. Winds should be generally strong from the SW throughout the week.
Avalanche Summary
Recent observations include several one natural size 2.5 wind slab from a large cross-loaded alpine slope, and several size 1-1.5 intentionally skier triggered slabs on steep wind loaded rolls. Avalanche activity will be on the rise over the next few days with incoming snow/rain, wind, and warming.
Snowpack Summary
Around 30-50 cm of recent storm snow has fallen in the past couple days, with much more expected this week. The new snow was relatively light initially but we may see heavier moist snow fall as temperatures start to rise, leaving us with an 'upside down' slab situation. Recent moderate or strong SW winds have created dense wind slabs in lee and cross-loaded terrain. A buried rain crust and/or surface hoar layer is down about 50-60 cm. Observations of the strength at this interface have been limited. The November crust near the bottom of the snowpack is generally well bonded, but may still be reactive in areas with a shallow snowpack, or with a very heavy load.
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.