South Rockies

Fair - Timing, track, or intensity of incoming weather is uncertain on Saturday

A deep trough off the coast continues to move an unstable air mass through the forecast period. Unsettled weather continues until Sunday. A weak ridge of high pressure will bring cooling and clear sunny skies Sunday afternoon into Monday. Solar radiation could be strong. Saturday: Snow amounts 10-20 cm. Ridgetop winds moderate from the South. Alpine temperatures near -8. Freezing levels 1800-2000 m. Sunday: Overcast in the morning, with light snow amounts. Freezing levels 1000 m. clearing in the afternoon with sunny periods. Solar radiation may be strong. Monday: Mainly sunny, possible light snow amounts for the far SE corner. Alpine temperatures near -15. Freezing levels at valley bottom.

Only audible avalanche activity reported from upper elevations in the Crowsnest North. Explosive avalanche control work produced size 1-2 avalanches on NE-S aspects. In the Lizard Range loose wet avalanche activity occurred on all aspects below 1600 m. This may have also occurred in areas of the S. Rockies. Last Friday, a snowmobiler was killed in a size 3 slab on a south-west aspect at treeline in the Corbin Creek area and a skier was injured in an avalanche in steep terrain in the Flathead Range. Conditions continue to remain tricky to predict, and manage. Large avalanches are still possible due to buried weak layers. Expect avalanche danger to elevate with unsettled weather conditions, and possible solar radiation, which will deteriorate the upper snowpack.

Earlier in the week the region has received 30-40 cm of storm snow. An additional 15-25 cm fell overnight Wednesday. Touchy storm slabs exist at all elevations. Strong SW winds have created stiff wind slabs behind ridges and terrain breaks. The mid February surface hoar layer in the upper snowpack is most prevalent in the west and south of the region, particularly in the Flathead. Recent snowpack tests, as well as rider-triggered avalanches, on this weak layer indicate that it still has the potential to be triggered in many areas, resulting in a large destructive avalanche. Remote-triggering (from afar) and triggering on low-angled terrain are also concerns. Basal facets may still exist, particularly in shallower snowpack areas with steep, rocky start zones. Cornices have grown large and threaten slopes below. Snowpack structures are variable across the region. With possible sunny periods starting Sunday, I suspect the new storm snow could become reactive under the influence of solar radiation. It's possible that solar induced avalanches could step down to deeper weak layers, creating large avalanches. There is a fantastic Forum Post from Michel Ridge, North Flathead Area. This includes recent observations by the CAC South Rockies field team. Check it out! https://avalanche.ca/Forums/forums/t/5565.aspx