Avalanche Forecast

Fair - Freezing levels are uncertain on Monday

Synopsis: Heavy precipitation and strong SW winds continue to hammer the region tonight and Monday with 25-50 mm possible. The freezing level should climb overnight from 1000 m to a little over 2000 m by Monday morning. Its hard to say how much snow will accumulate. It all depends on the timing and extent of the warming. Some areas could see rain all the way to ridge top. Precipitation and wind taper off on Tuesday but temperatures remain warm with a freezing level around 2500 m. Expect a mix of sun and cloud on Wednesday with continued warm temperatures and light winds.

It's likely there will be a fairly large and widespread natural avalanche cycle at some point on Monday (or late Sunday), and it could continue throughout the day if heavy precipitation persists. Avoid all avalanche terrain and be aware of what is above you. Large avalanches could reach the end of run out zones.

New snow sits on a previous variable snow surface that included wind affected surfaces (crust, hard and soft slabs), a freezing rain crust or sun crust, and surface hoar or sugary facets in sheltered shady terrain. How well the new snow bonds to this surface is the question. This storm is starting cold and will finish much warmer, meaning that the new storm snow will be more dense on top - a good recipe for slabs. Below the new we might find the mid-December surface hoar or crust/facet weak layers. These are buried between 40 and 80 cm deep on average. The surface hoar layer may be found in sheltered shady areas at and below treeline, while the crust/facet layer could be more widespread but also more variable. Reports suggest is could be between 0 and 120 cm deep depending on exposure to wind. Heavy loading in the coming days could trigger these weaknesses creating very large avalanches.