Regions
Northwest Coastal.
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Thursday
Weather Forecast
Tuesday: Freezing Level: 500m rising to 750m, Wind: Light W, No significant precip.Wednesday: Freezing Level: 500m Wind: SW, initially moderate increasing to strong by sundown. 10 - 15 expected during the day.Thursday: Freezing Level: 500m Wind: Strong SW backing off of to moderate SW in the evening. 10 - 20 cm expected during the day.
Avalanche Summary
No new avalanche activity was reported on Sunday. On Saturday, visibility improved on Saturday revealed the extent of a large natural avalanche cycle in the North. The big winds and large snowfall drove a cycle to size 3.5. Observations in the southern half of the region were much smaller with cornice failures resulting in size 2 avalanches. The sun is really gaining strength as we get closer to the Spring Equinox which is driving ongoing point releases on solar aspects.
Snowpack Summary
The recent storm snow continues to settle and gain strength as it bonds with the underlying snowpack. Winds have been blowing with enough energy to move snow, and with 70 cm of storm snow in the north and 20 cm in the south, there's no shortage of new snow to move around. As a result, slabs have been developing near ridgecrest and in wind exposed locations at treeeline. Slab properties likely vary from upside down soft slab to stiff and deep wind slab. 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
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.