Regions
Northwest Coastal.
Weather Forecast
Synopsis: A series of frontal systems is expected to affect the region over the next few days bringing steady precipitation and seasonal temperatures. Overnight and Thursday: Periods of snow – 20-30 cm. The freezing level is around 600 m. Winds are moderate to strong from the west-southwest. Friday: Heavy snowfall – 30-40 cm. The freezing level remains around 500-600 m and winds are strong from the west.Saturday: Cloudy with light snow. The freezing level is around 500 m and winds ease to moderate from the southwest.
Avalanche Summary
Recent natural avalanche activity is limited to size 1-1.5 loose snow avalanches in steep terrain. Explosive control in Bear Pass produced a few size 2-2.5 slab avalanches on Tuesday.
Snowpack Summary
A layer of surface hoar and a sun crust are now buried by a few cm's of new snow. Below this the recent storm snow has settled and gained strength over the past couple days. Pockets of wind slab have formed on a variety of aspects in exposed terrain near ridge crests, and may be susceptible to triggering in steep terrain. Cornices that now loom over many features may become weak with continued growth and/or daytime warming. The mid and lower snowpack layers are generally well settled.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.