A "weather bomb" will drive avalanche danger to HIGH on Thursday. It might be a good time to hunker down and wait out the storm. If you are heading out, stick to simple or non-avalanche terrain.
Avalanche Summary
A widespread and large natural avalanche cycle is expected throughout the day on Thursday in response to rapid loading from snow and wind. We could see slab avalanches up to size 3, with large slides more likely on north-facing, wind-loaded slopes.
Snowpack Summary
The current snow surface consists of soft wind slabs in exposed lee terrain, dry lower density snow in sheltered terrain, and some places have mentioned small surface hoar forming overnight on Tuesday. Forecast heavy snowfall, warming, and very strong winds will rapidly create fresh storm slabs everywhere, and deep wind slabs in exposed lee terrain for Thursday. Some areas could see close to 100 cm in a 24 hour period! Expect a widespread and large natural avalanche cycle during the storm. Ongoing stormy weather has also encouraged extensive cornice growth. The mid and lower snowpack are strong and 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.