Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain on Saturday

Enjoy the brief lull in the weather Thursday and Friday, it looks like we will be right back into the storm track this weekend. What happens beyond that is a bit uncertain, but a ridge of high pressure will likely take us into the New Year.WEDNESDAY NIGHT: Freezing level at valley bottom, light variable wind, trace of snow possible. THURSDAY: Broken cloud cover, freezing level at valley bottom, light west wind at most elevations with moderate northwest gusts near ridgetop, no significant precipitation expected. FRIDAY: Overcast, freezing level at valley bottom, light to moderate southerly wind at valley bottom with strong west/southwest wind in the alpine, 2 to 10 cm of snow during the day, 10 to 25 cm Friday night. SATURDAY: Overcast, freezing level beginning at valley bottom, rising to around 1500 m by sunset. Strong to extreme southwest wind, 15 to 25 cm of snow.

No new avalanche activity to report from Tuesday. On Monday a natural size 3 avalanche was reported from a steep south facing aspect at 1500 m. The avalanche likely failed on the ground running on what looked to be a grass slope from far away.A few large (size 2-3) natural persistent slab avalanches were reported on Sunday. These avalanches were reported on south aspects in the alpine and failed on failed on weak layers 150 cm below the surface. Last week numerous persistent slab avalanches (up to size 3) were reported on all aspects (a few that even destroyed mature trees). The persistent slabs were 50-150 cm thick and likely failed on the early December weak layer. The same layer was responsible for several large human triggered avalanches earlier this month (see this MIN report for an example), and although there are no recent reports of human triggered avalanches, professionals are still being very cautious with their terrain choices because of this layer.

Low density snow from the past few days sits above wind affected snow in the alpine and around treeline.A weak layer that formed during the dry spell in early December is now 80-120 cm deep. The layer is composed of weak facets, surface hoar, and a sun crust on steep south-facing slopes. VARDA has posted a video that provides a great visual on our snowpack. This layer has been responsible for large persistent slab avalanches over the past two weeks, particularly on northeast facing slopes between 1900-2300 m and on steep south-facing slopes in the alpine.Another weak layer from mid-November is now buried up to 150 cm and a crust that formed in late October is found near the bottom of the snowpack. The probability of triggering these deeper layers is low, but the most suspect areas would be shallow spots in steep rocky terrain.