The Avalanche Danger is expected to rise throughout the day on Wednesday, and heavy accumulations are possible in the far south of the region. Pay close attention to how much snow falls in your area, and be prepared to back off to simple terrain.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Wednesday
Weather Forecast
On Wednesday expect 10-25cm of new snow to fall throughout the day with strong southwest ridgetop winds. The highest accumulations are forecast for the south of the region. Continued light flurries and decreased winds are forecast for Thursday, while clearing skies are forecast for Friday. Freezing levels should sit at 1400m on Wednesday, 1200m on Thursday, and 1600m on Friday.
Avalanche Summary
No new avalanches have been reported, but this may speak more to a lack of observations rather than actual conditions. In recent days in the neighboring Sea to Sky region a few soft slabs to size 2 were observed failing within the new storm snow at treeline and in the alpine. Daytime warming and solar radiation also triggered loose wet avalanches to size 2.5 in steep sun-exposed terrain. Similar conditions are expected to have developed in this region. Forecast cooling should limit ongoing loose wet avalanche activity; however, a round of natural wind slab activity is expected on Wednesday in response to new snow and strong southwest winds.
Snowpack Summary
On Sunday night the region received up to 15cm of new snow with highest amounts falling in the northern parts of the region (areas accessed from the Pemberton Valley). Further south in the Coquihalla area, it rained to ridgetop and depending on the current temperature, surfaces are either moist or refrozen. Where it did snow, moderate southerly winds formed soft slabs which seemed most reactive in lee alpine terrain, although warm temperatures and the "greenhouse effect" from cloudy skies on Tuesday have surely promoted significant settlement. The new snow overlies a sun crust on sun-exposed slopes, dry settled powder on shady slopes and moist snow below 1800m. Below the new snow the snowpack is strong and well-settled throughout with no notable persistent weaknesses. Cornices are huge and fragile.
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.