Regions
Kootenay Boundary.
The new snow will require time to settle in areas that saw more than 25cm of new snow (near Nelson and Kootenay Pass).Keep a close eye on how the new snow is bonding to the old surface below.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Unsettled weather until the next system arrives on Wednesday. Freezing levels will gradually increase towards the end of the week.TUESDAY: Cloudy with flurries (3-5 cm) / Light to moderate south west wind / Alpine temperature -7 / Freezing level 1200m WEDNESDAY: Cloudy with flurries (5-10 cm) / Moderate south west wind / Alpine temperature -5 / Freezing level 1000m THURSDAY: Lingering flurries (5 cm possible) / Light to moderate southwest wind / Alpine temperature -3 / Freezing level 1800m
Avalanche Summary
On Monday we received reports of widespread natural storm slab avalanches to size 1.5 on all aspects in Kootenay Pass. Crowns averaged 10-25cm thickness. On Friday, cornice control work resulted in triggering a size 2 wind slab below, on an east aspect near 2200m. Slab depth averaged 20cm.
Snowpack Summary
Well that was quite a storm, wasn't it Nelson? The region saw wildly variable amounts of new snow on Monday morning, ranging from 2cm to 48cm near Nelson!!!The new snow sits on firm crusts on sunny aspects, and all aspects below 1900m. On higher, shady aspects, the new snow may sit on some old wind slabs from last week, or a mix of large surface hoar and surface facets. Another weak layer buried mid March is down 50 to 120cm and is a crust on solar aspects and surface hoar (to 6mm) on high elevation north. A few other persistent weak layers are buried in the mid and lower snowpack, but they have gone dormant and are unlikely to resurface until we move into a period with consecutive above-freezing nights.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.