Avalanche Forecast

Moderate - Due to the number of field observations

TUESDAY: Mainly cloudy. Ridge wind moderate, west. Temperature -8. Freezing level valley bottom.WEDNESDAY: Cloudy, light flurries. Accumulation trace. Ridge wind moderate to strong, west. Temperature -4. Freezing level 1400 m.THURSDAY: Snow. Accumulation 20-30 cm. Ridge wind light gusting strong, east. Temperature -4. Freezing level 1300 m.

In the neighboring Lizard Range the east facing Mt. Corrigan slide path produced a very large natural avalanche Saturday. The avalanche is estimated to be a size 4.0, and it took out mature timber in the path as it overran the Flathead FSR south of Corbin. .Photos here. Reports are limited, but there was one explosive triggered wind slab avalanche east of the divide on Saturday. There was likely natural wind slab activity in the northeast part of the region where the heaviest accumulations occurred.On Friday, a snowmobiler was partially buried by a size 2 avalanche in the Alexander Creek drainage. The avalanche occurred on a north aspect around 2000 m and failed on weak snow near the ground. See Report here. A few small wind slabs were triggered by skiers in lee terrain on Thursday and Friday.A few large persistent slab avalanches that released during last weekend's storm were observed last week as well. These avalanches failed on deep weak layers from November and December, resulting in large avalanches (size 3). Most were triggered by cornices falling on north and east facing slopes.

An upslope storm has delivered lots of cold low density snow east of the divide since Saturday (20-40 cm). The distribution of new snow is highly variable, and so are the surface snow conditions. The western parts of the region in BC were relatively warm with less snow, while areas in Alberta and around the divide were much colder and windier which likely formed touchy wind slabs in open terrain.The lower snowpack in this region is weak, with a number of concerning weak layers. A layer buried mid-January is composed of surface hoar on sheltered aspects and a sun crust on solar aspects is now 60-80 cm deep. Another surface hoar layer from early-January is buried 70-90 cm deep. A widespread weak layer from mid-December composed of facets, crusts, and surface hoar is 100-150 cm deep. Finally, a rain crust with sugary facets buried in late-November is near the bottom of the snowpack. Although the snowpack structure is variable across the region, these persistent weak layers are generally widespread.