New snow, rising temperatures and strong winds make perfect conditions for avalanches !
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
On Saturday we are expecting 10 to 20mm of moisture with freezing levels dropping to 1000m by Sunday morning. Sunday and Monday will see another 10 to 20mm with freezing levels around 1200m. Moderate to strong winds above 1500m will accompany this system.
Avalanche Summary
One report from yesterday of a natural wind slab avalanche, size 2, on a North East aspect, wind-loaded at 2000m. A few wet snow avalanches have been reported occurring on solar aspects. Cloudy skies may keep the surface from overnight freezing and rising temperatures may increase the likelihood of loose wet avalanches and cornice failures.
Snowpack Summary
Incoming precipitation will fall on a variety of old snow surfaces that exist throughout the region. There are numerous crusts and old wind slabs buried in the snowpack above treeline that may still be problematic. Below treeline the snowpack has had numerous warming and rain events and should be bombproof for the most part. Rain has recently been reported to ridge tops in the Coquihalla region. Solar aspects are reported to be going isothermal in some areas below 1600m
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.
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.