Forecast snowfall amounts are highly variable throughout the region with the south and direct coastal areas expecting the see the highest accumulations. Pay attention to local conditions.
Confidence
Fair - Track of incoming weather systems is uncertain on Wednesday
Weather Forecast
Overview: The jet stream will flatten out allowing a series of pacific systems to impact the region with the south seeing the highest accumulations.Wednesday: Moderate snowfall / Moderate southwest winds / Freezing level at 1200mThursday: Moderate to locally heavy snowfall with the most intense precipitation falling late in the day / Strong to extreme southwest winds / Freezing level at 900mFriday: Moderate snowfall / Moderate to extreme westerly winds / Freezing level at 1200m
Avalanche Summary
No new avalanches were reported.
Snowpack Summary
Northerly outflow winds have stripped north aspects and developed sastrugi waves in open, high elevation terrain. Sheltered slopes at treeline have seen surface hoar development, while previously sun-exposed slopes are now sporting a melt-freeze crust. New snow forecast for the week will cover these surfaces.The cold temperatures from early December have left weak faceted crystals that seem to be variably reactive. In higher elevation terrain where the snowpack was deeper, the facets likely co-exist with a crust in the mid pack. In lower elevation terrain or in shallow, rocky areas of the alpine, the facets are most likely more widespread and may exist down near the ground. Either way, the "wait 48 hours and you're good" Coastal mantra does not apply as these conditions are likely to persist for some time, and may become reactive with forecast snowfall.Early season riding hazards such as rocks, stumps and logs are lurking below the surface in many areas. In glaciated terrain open and poorly bridged crevasses are everywhere.
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.