Avalanche Forecast

Low - Timing, track, or intensity of incoming weather system is uncertain on Monday

A modified Arctic air mass combined with some upslope snowfall should shake up the South Rockies snow globe on Monday while keeping temperatures cool. A drying trend takes hold on Tuesday that is expected to last through Wednesday before the promise of yet another storm on Thursday. Stay tuned for more details. MONDAY: Overcast, with a chance for some clearing late in the day, freezing level at valley bottom, moderate variable winds out of the west in the morning shifting to the east before returning to the west late in the day, 10 to 15 cm of snow. TUESDAY: Broken cloud cover initially, clearing throughout the day, freezing level at valley bottom, light variable winds at treeline, strong northwest wind at ridge top, no significant snowfall expected. WEDNESDAY: Clear skies in the morning, cloud cover steadily increasing though the day, freezing level at valley bottom, strong west wind, no snow expected until Wednesday night.

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 on Saturday and Sunday (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 30-50 cm deep. Another surface hoar layer from early-January is buried 40-60 cm deep. A widespread weak layer from mid-December composed of facets, crusts, and surface hoar is 60-80 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.