Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain

THURSDAY NIGHT: 10-20 cm of snow, strong wind from the southwest, alpine temperatures drop to -8 C.FRIDAY: Continued snowfall with another 5-15 cm, moderate to strong wind from the south wind, alpine high temperatures around -5 C.SATURDAY: Scattered flurries then clearing in the afternoon, light to moderate wind from the west, alpine high temperatures around -5 C.SUNDAY: Mostly cloudy, moderate wind from the south, alpine high temperatures around -7 C.

Natural avalanche activity will likely continue into Friday as the tail end of the storm continues to build large and touchy storm slabs. At this point we don't have reports on avalanches during the storm, but we suspect large natural avalanches are occurring.Prior to the storm, several human triggered avalanches were reported in the region, including small slabs (30 cm thick) on buried surface hoar at Sugar Bowl (see this MIN report for details). Last weekend, there was a social media report describing an avalanche involvement that resulted in the partial burial of one individual in the Allan Creek area on Sunday. The rider's use of an airbag pack appears to have aided a quick and successful companion rescue.

By Friday, a total of 40-80 cm of new snow will have fallen over a 48 hour period. The new snow sits atop 30-40 cm of settling snow from last weekend's storm, which sits above a layer of surface hoar that was reportedly widespread at treeline and above. The overall combination of new snow and strong wind has likely blanketed the region with thick storm slabs.A layer buried 150-200 cm composed of weak facets, surface hoar, and a sun crust on steep south-facing slopes is believed to be gaining strength. Places that might still challenge this assumption would be steep north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpine.A weak layer from mid-November and a crust that formed in late October are 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.