Avalanche Forecast

Moderate -

Monday night: Becoming cloudy with eventual flurries bringing 5-10 cm of new snow by morning, mostly focused toward the north of the region. Moderate to strong northwest winds.Tuesday: Cloudy with continuing flurries bringing another approximately 5 cm of new snow, again focused toward the north of the region. Moderate to strong northwest or west winds. Alpine high temperatures reaching about -3 under a mild temperature inversion.Wednesday: Cloudy with increasing flurries bringing up to about 10 cm of new snow, continuing overnight. Strong southwest winds. Alpine high temperatures around -4.Thursday: Cloudy with lingering flurries bringing an uncertain 5-20 or more cm of new snow, continuing overnight. Strong to extreme south winds. Alpine high temperatures reaching to around -1 with freezing levels jumping to a possible 1800 metres.

We have 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 effort. Clearing weather on Sunday also allowed for observations of several natural storm slab releases just southwest of Valemount. These reached size 2.5 and were mainly confined to steep alpine features, but in some cases ran to valley bottom. Prior to the storm, a few large (size 2-3) natural persistent slab avalanches were reported last Sunday. These avalanches were reported on south aspects in the alpine. Last week numerous persistent slab avalanches (up to size 3) were reported on all aspects. The persistent slabs were 50-150 cm thick and likely failed on the early December weak layer. The inability of our recent storm to produce a renewal of persistent slab activity suggests that this layer may finally have become dormant.Looking forward, anticipate the potential for human triggering to remain elevated. The existence of surface hoar beneath our new snow is likely to prolong unstable conditions.

Saturday's storm brought about 35-45 cm of new snow to the region. In many areas, the new snow will overlie a weak layer of surface hoar that was reportedly widespread at treeline and above in advance of the storm. This weak interface covers a few cm of storm snow from light snowfalls in days prior to the storm.Avalanche activity on the 110-180 cm deep weak layer that formed during the dry spell in early December has greatly diminished over the last week. This layer is composed of weak facets, surface hoar, and a sun crust on steep south-facing slopes. It is believed to be trending toward a dormant state after the loading test brought by Saturday's storm failed to produce consistent reports of avalanches 'stepping down'. Places that might still challenge this assumption of dormancy would be steep north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpineA 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.