Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Moderate snow amounts Tuesday night into Wednesday morning. Ridgetop winds strong from the NW. A weak ridge of high pressure will bring mainly dry, cool conditions on Thursday. Ridgetop winds 20-30km/hr from the NW. Things will start to ramp up on Friday as a new low arrives off the coast bringing moderate precipitation and strong SW ridgetop winds.
Avalanche Summary
Reports of several natural size 1 soft slabs failing on lee features in alpine terrain. Several skier triggered size 1's have been reported on steeper North aspects near 1900m, crown depths 20cms with good propagation. I suspect there will be an increase in avalanche activity with the forecast wind and snow.
Snowpack Summary
New snow over the past few days have buried a variety of old snow surfaces. These old surfaces are now 30-45cm down and include crusts that exist on all aspects at lower elevations and on steep solar aspects higher up. Facets (sugary snow crystals) and spotty surface hoar (feathery snow crystals) may also exist in combination with crusts, so there may be continued slab reactivity at lower elevations. With more snow and wind in the forecast the new load may have a poor bond to the underlying buried surfaces. The mid and lower snowpack are strong and well settled. The average treeline snowpack depth is about 240cm.
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.