South Rockies

We have had a vague report of an avalanche incident yesterday in which a skier triggered a size 2 slab avalanche on an E facing slope at top of treeline in an area in the N end of the Flathead. Yesterday, our field team also observed several natural avalanches up to size 3 in Elk Valley South out of steep alpine features some of which would have run to ground. In an area NW of Elkford, several large avalanches ran full path or close to full path on S and E facing slopes and left deep deposits on the trail. These would have occurred during or right after the storm.

Good

Tonight and Tuesday: A slight chance of precipitation with a weak upper disturbance passing through the region late Tuesday. NW winds becoming lighter in the afternoon with freezing levels at the surface.Wednesday: Another system is tracking through the region. Light precipitations are expected and winds should pick up again and blow from the W moderately. Freezing levels should remain at valley bottom. Thursday: Similar situation for Thursday as a more zonal flow is allowing frontal systems to move across BC. Precipitation amounts are still not certain but they look a little bit less than the previous system.

Today's moderate and strong winds from the SE most likely created more pockets of windslab on lee side below ridgetop in the alpine and at the top of treeline. I could see those being very sensitive to skier triggering. Cornices have probably grown since this wind event as well.  The storm slab is settling but is still sensitive to human trigger, especially where a weak faceted snowpack is underlying that top fresh layer. The facet/crust layer down 80-100 cm at treeline and below treeline  and the depth hoar layer in the alpine seems quite reactive on E aspects. Multiple recent natural and human triggered avalanches on this aspect is a good sign of that problem.