Regions
Northwest Coastal.
Caution is required in exposed wind-affected terrain on Friday.
Weather Forecast
FRIDAY: Cloudy with sunny breaks and a chance of flurries (2-5 cm). The freezing level is around 800 m and winds are moderate to strong from the SE. SATURDAY: Cloudy with sunny breaks and a chance of flurries. The freezing level is around 800-1000 m and winds are light from the SE. SUNDAY: Cloudy with sunny breaks. The freezing level is near 1000 m and winds are light.
Avalanche Summary
Sunny breaks in the northern part of the region on Wednesday led to a few natural cornice falls and slab avalanches up to size 3 on steep solar aspects. There were also reports of a few natural wind slabs up to size 2.5 from wind-loaded alpine slopes. Skier testing produced a few size 1 wind slabs in steep lee terrain.
Snowpack Summary
Cloudier conditions and moderate snowfall persisted in the southern part of the region on Wednesday, while norther sections saw sunny breaks and only light snow. Expect a surface melt-freeze crust in areas where the sun was a factor. Ongoing strong winds have shifted the new snow into hard or soft wind slabs at treeline and in the alpine, maintaining a wind slab problem on northerly aspects and scouring leeward slopes. Some areas are reporting a weak surface hoar layer near the base of the 50-70 cm of recent storm snow. An old crust buried in early February can now be found around 80-120 cm below the surface. This crust, which may coexist with small facets or decomposing surface hoar, recently produced sudden planar ("pops") results in snowpack tests. Although no recent avalanches were reported to have failed at this interface, I'd remain suspicious of this layer in steep, unsupported terrain at treeline and in the alpine.
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.
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.