Avalanche Forecast

Moderate - Timing, track, or intensity of incoming weather system is uncertain

SUNDAY: Cloudy with snowfall, accumulation 15-30 cm, strong to extreme southwesterly winds, alpine temperature -8 C, freezing level near 900 m.MONDAY: Mostly cloudy with light snowfall, accumulation 2-5 cm, light to moderate southwesterly winds, alpine temperature near -9 C, freezing level near 800 m.TUESDAY: Partly cloudy with intermittent snowfall, accumulation 1-3 cm, light to moderate southwesterly winds, alpine temperature near -10 C, freezing level near 600 m.

On Friday, there were several reports of small to large (size 2 to 3) persistent slab avalanches, triggered naturally and by skiers and snowmobilers. They were about 90 cm deep on northerly aspects at all elevations. Expect similar avalanches to release on all aspects with new load.On Thursday, avalanche activity was reported as storm and persistent slabs. Storm slabs were running to size 2 on southerly and northerly aspects in the alpine and tree line. There were two persistent slab avalanches reported that were both skier triggered 80cm deep between 1100 and 1400m on north aspects. One of them was remotely triggered (from a distance) from 60m away and was a size 2.5. The other was triggered by a ski cut and was a size 1, yet still 80cm deep. On Wednesday, a small natural avalanche cycle was reported from steep ridge features. Fast and loose sluffing was also reported.

The current snowpack is complex, we now have three active weak layers that we are monitoring. 15-40 cm of storm snow and another 10-30 cm of forecasted snow for Sunday sits on a newly formed crust and/or surface hoar layer (mid-January). Prior to the storm the crust was reportedly widespread; high elevation north is likely one of the few crust-free zones. The mid-January surface hoar is up to 10 mm and reported at all elevation bands. The new snow is falling with strong southwesterly winds, producing wind slabs in lee features. Deeper in the snowpack, the early-January persistent weak layer is 30 to 60 cm below the surface. It is composed of surface hoar on sheltered slopes and sun crust on steep solar aspects and found at all elevation bands. Snowpack tests show sudden fracture characters with moderate loads and high propagation potential, as well as whumpfs and cracking. Another weak layer buried mid-December consisting of a facet/surface hoar/crust combination is buried 40 to 100 cm deep. It is most problematic at and below tree line.A rain crust buried in November is 100 to 150 cm deep and is likely dormant for the time being.