Regions
Northwest Coastal.
A moist snow surface is an indicator that the warm and sunny conditions are weakening the snowpack. Avoid steep sun exposed slopes during the afternoon.Are you a member of Avalanche Canada? Join today at avalanche.ca/membership
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
A ridge of high pressure is the dominate feature for the next three days resulting in dry and sunny conditions. On Saturday, there is some model uncertainty regarding freezing levels which could reach as high as 2000m in parts of the region but will more likely be around 1500m. This warm air coupled with sunny conditions could make it feel unusually warm in the alpine for February. Temperature inversions are possible and it may be cooler in the valleys. Alpine winds on Saturday are forecast to be moderate-to-strong from the NW switching to NE. On Sunday, warm air conditions are again possible at higher elevations. Alpine winds are forecast to remain moderate-to-strong from the N-NW. On Monday, freezing levels are forecast to return to normal and be 500-800m. Strong outflow winds are expected for Monday.
Avalanche Summary
On Thursday, several size 1 skier initiated avalanches were reported. It is expected that these were thin wind slabs. Last week several full-depth avalanches up to Size 3 were observed on all but North aspects. If the region gets substantial warming and sun on Saturday, isolated events like these could once again become active. Loose sluffs from steep sun exposed slopes are also possible.
Snowpack Summary
A dusting of new snow has buried the previously variable snow surface which may have included wind-pressed surfaces or old wind slabs, a sun crust or old rain crust, surface hoar, and/or surface facets. A layer of surface hoar buried in the upper snowpack has been reported in some areas and is worth investigating before committing to any big alpine terrain. At the base of the snowpack, weak facets may be persisting.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.