The atmospheric river of warm moisture is upon us. Look for an avalanche danger increasing to HIGH later today.
Weather Forecast
Wet flurries Mod SW wind gusting to strong, and freezing level bumping up to 2900m later today. Temperatures are already above freezing at Round Hill station at 2100m. The forecast atmospheric river is upon us and will bring high freezing levels, moderate to strong SW winds and heavy precipitation into Thursday afternoon.
Snowpack Summary
Warm temps and a mix of rain and snow are destabilizing surface layers in the snowpack. Last weekend's storm snow will be settling rapidly. Mod shears in the storm snow down 40cm and 60cm at 2000m yesterday. The Oct 31st crust down 100cm should awaken in the next 48hrs.
Avalanche Summary
One new size 2 avalanche recorded yesterday in the highway corridor. Expecting an avalanche cycle to start on Wednesday and continue into the afternoon on Thursday.
Confidence
Timing of incoming weather systems is uncertain
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.