Confidence
Fair - Freezing levels are uncertain on Friday
Weather Forecast
Wednesday: light snowfall on tuesday night continuing through wednesday morning easing in the afternoon / moderate southwest winds turning light and northwest / freezing level at 900m Thursday: mostly clear / moderate southwest winds / freezing level at about 900m Friday: clear skies with a significant warming trend / light to moderate southwest winds
Avalanche Summary
No avalanches have been observed in the last 24 hours. A significant warming trend is expected for thursday/friday. Expect avalanche activity to increase with this trend.
Snowpack Summary
On saturday night and sunday the region saw moderate to strong southwest winds and moderate precipitation (heavy precip in the Coquihalla). For most of the period rain fell to about 1700m, but freezing levels fluctuated during the storm. In the Duffey Lake area light amounts of more recent snow now sit above a new rain crust that has formed below 1700m while fresh soft wind slabs rest over cohesive stubborn wind slabs at higher elevations. In the Coquihalla area temperatures have been slower to drop. The warmer present temperatures combined with the higher snowfall/rain values in this area means that deep wind slabs been generally slower to stabilize. More recent soft wind slabs now sit on top. With the recent wind and snowfall there are widespread unstable cornices. Any cornice fall would be destructive by itself, but could also be a trigger for the slope below. Persistent weak layers lower down in the snowpack have generally ceased to be of concern, except perhaps in very isolated, thin rocky areas.Most recently, the Coquihalla area has been receiving the most snowfall with current snowpack depths at treeline amounting to 390cm. In the Duffey Lake area, treeline depths are closer to 240cm.
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.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.