Regions
Kootenay Boundary.
Cloud cover with higher freezing levels may continue to add warmth to the snowpack and keep the recent storm snow reactive
Confidence
Moderate - Freezing levels are uncertain on Saturday
Weather Forecast
SATURDAY: Cloudy with isolated flurries / Moderate southwest wind / Alpine temperature -2 / Freezing level 1600mSUNDAY: Mix of sun and cloud / Light to moderate northwest wind / Alpine temperature -4 / Freezing level 1200mMONDAY: Mix of sun and cloud / Light north wind / Alpine temperature -4 / Freezing level 1200m
Avalanche Summary
Reports on Thursday indicate several natural avalanches running during a warming event to size 2.5 and 3. These were triggered on the March 21 melt freeze crust by cornice falls and a skier triggering a smaller avalanche that subsequently stepped down to the crust. They were running on northerly aspects in the alpine and tree line elevation bands. One report from Wednesday detailed a size 2 remotely triggered avalanche running on the same crust. This ran on an east aspect at 1900m and was 50cm deep.
Snowpack Summary
A series of snowfalls throughout the past week accumulated roughly 60-90 cm of moist new snow in the region. Periodic high freezing levels and solar exposure over the same period has formed a variety crusts within and/or on the surface of the storm snow up to 2000m. This all overlies a rain crust that was buried on March 21 up into the alpine. This crust is reported to be recently reactive to heavy loads. At upper elevations, above 2100m approximately, the late and mid-February persistent weak layers (100-150cm down) and basal facets in shallow snowpack areas may still exist. There is no recent information on the presence or reactivity of these persistent layers. For this reason it would be prudent to investigate their presence if traveling in the highest alpine areas of the region.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.