Confidence
Fair - Due to variable snowpack conditions
Weather Forecast
Synopsis: Precip amps up Tuesday night but should taper off by Wednesday morning in the northern half of the region. The southern portion of the region should see significant precip through most of the day Wednesday. The trailing cold front brings freezing levels down slightly with no significant precipitation expected through the duration of the forecast period. Wednesday: Freezing Level: 1300m (North) Precip: 2/5mm – 2/8cm. (South) Precip 15-20mm – 15 -35cm Wind: Strong, WThursday: Freezing Level: 1000m Precip: Nil Wind: Strong, W/SWFriday: Freezing Level: 1000m Precip: Trace Wind: Mod, SW.
Avalanche Summary
A couple of notable small avalanches were triggered on a large alpine feature in the Pemberton area Monday. A skier remote triggered a size 1.5 avalanche from 50m away on a NW facing slope that sympathetically triggered another size 1 avalanche. These are small avalanches, but it's the mechanics that are interesting. A few small skier controlled avalanches were reported on Sunday. These events occurred in steep terrain at or above treeline and failed within the storm snow just above the recently buried crust/ moist snow.
Snowpack Summary
Recent snowfall amounts vary significantly within the region from north to south. In the Duffy Lake area and north expect to find 20-25 cm of fresh snow, while Coquihalla and Allison Pass areas have seen 50 cm or more. Moderate or strong south or westerly winds left variable snow distribution in exposed areas near ridgetop with dense wind slabs forming in lee and cross-loaded features. The new snow is sitting on moist snow or a melt-freeze crust depending on elevation. Weaknesses exist within the storm snow and the bond between the new snow and crust is questionable. A frontal system passes over the region Tuesday evening which should bring snow above 1500m. Rain falling below treeline is unlikely to have much affect. Cornices are very large and looming over many ridgelines.
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.