Regions
Kootenay Boundary.
Be alert to conditions that change with elevation. A saturated snowpack means avalanches have the potential to entrain significantly more mass than usual.
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Synopsis: A series of fronts is sliding down the BC coast. The warm front should pass over the Southern Interior on Saturday evening, followed by the cold front Sunday. Expect 20-40mm of precipitation before conditions dry out on Monday.Tonight and Saturday: Snow or rain starting late in the day / Strong SW winds / Freezing levels 2100mSunday: Snow or rain / Strong W winds / Freezing levels 2200mMonday: Flurries / Light NW winds / Freezing levels 1400-1700m.
Avalanche Summary
A cycle of large natural, accidental and controlled storm and wet slab avalanche occurred Thursday in response to heavy loading and mild temperatures. These avalanche were reported to be entraining significant mass through their track, trenching down the the midpack crust or through to ground.A large persistent slab avalanche was remotely triggered by a skier on the the early February weakness. This is a good reminder that although there has not been much activity on this layer for a while it is still a lingering problem in the snowpack. Natural activity tapered off on Friday as conditions dried out briefly.
Snowpack Summary
The recent storm snows are rapidly settling into a soft slab. This snow sits above a variety of old surfaces. A layer of facets can be found on north aspects with a sun crust on many south facing slopes. Recent rains up to 1800m are saturating the upper snowpack. At elevations above the freezing level sustained SW winds have have formed winds labs in lee features. The midpack is broken by a widespread persistent weak layer found down 90 to 120cm. The form of this week layer varies from surface hoar to a sun crust and/or facets. It can be found at all elevations, on all aspects and is still a concern.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.