Warming temperatures and Solar radiation will play a leading role in the avalanche hazard in the coming days. Pay special attention to large ripe cornices !
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Synopsis: The Pineapple express that plowed its way across the province in the last few days has moved south and east leaving us with a high pressure and some clearer weather for the next few days.Tonight: Clear with cloudy periods, freezing level at valley bottom. ridge top winds light to moderate from the north west.Tuesday: Mix of sun and clouds, no precipitation in the forecast, light to moderate winds at ridge tops, freezing level climbs to 1500.Wednesday: Sunny with cloudy periods, no precipitation in the forecast, freezing level rising to 1800m. winds from the south west, light to moderate.Thursday: Sunny with cloudy periods, possibility of flurries, freezing level rising to 1500m. Light ridge top winds from the west.
Avalanche Summary
The numbers avalanches running naturally has diminished, with the bulk being in the south of the forecast area. Cornice failures are beginning to show up on the reports, and explosive testing is producing large avalanches with widespread propagations. Neighboring forecast regions have reported large avalanches initiating in the new storm snow, then stepping down to deeper layers, some running full path to the ground. The South Columbia's reported a size 4.5 on a south-west aspect than ran more that 1500 vertical metres.
Snowpack Summary
Recent snowfall amounts have been highly variable throughout the region. In some deeper snowpack areas 80 to 100cm of storm snow overlies a weak surface hoar layer that has been preserved in sheltered areas. A buried sun crust exists on solar aspects and and there are growing wind slabs in exposed terrain. On lee slopes these accumulations have been pushed into much deeper deposits by moderate to strong southwest winds. Warming has added cohesion to the slab and wider propagations have been reported. With rising temps and solar radiation, moist snow surfaces have been reported into the alpine.Wet avalanches on solar aspects have also been reported. There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies between 60 and 160cm below the surface, and includes surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. In manyparts of the forecast area, large destructive avalanches are still a very real concern with ongoing reports of natural avalanches running full path. Weak basal facets exist in many areas, but without a large load, triggering now is unlikely.
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.
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.