Spring sun could push the hazard higher than forecast on solar aspects. Keep an eye on cornice hazards
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Synopsis: A weak ridge of high pressure sits over the forecast area and should block out any major precipitation for the next 2 days.Tonight: Clear periods, no precipitation in the forecast, freezing level around 100 metres, winds light, from the north.Saturday: Cloudy with trace a of precipitation, freezing level around 1300 metres, ridge top winds should be light from the south east.Sunday: Cloudy periods, trace of precipitation in the forecast, freezing level around 1800 metres, light ridge top winds from the south west.Monday: Cloudy with flurries, freezing level around 2000 metres, winds light to moderate from the south.
Avalanche Summary
Avalanche activity from yesterday confined to small ( size 1 to 1.5 )soft slabs, wind slabs and some loose wet sluffs in steep south facing terrain. Caution should be exercised on solar aspects as the spring sun begins to heat things up. Cornices are becoming large and mature and deserve serious respect.
Snowpack Summary
Up to 60cm of snow has fallen in parts of the forecast region in the past 7 days. This storm snow combined with winds has continued to produced wind slabs overlying the storm slabs at tree line and above. The storm slab is sitting on a variety of layers. A well developed sun crust has formed on solar aspects and, prior to this storm, surface hoar formed on shady, sheltered slopes. At lower elevations, a melt-freeze (or rain) crust can be expected in most areas. Below the storm snow, the snowpack is generally well settled from the recently warm weather. Two persistent weak layers remain a concern but these problems are becoming more isolated. Before the recent storms, the early-March crust/facet layer was down roughly 1m and the early Feb. layer is down 1.5m or more. These layers are now deep enough that human-triggering is unlikely, but smaller avalanches or cornices failures have the potential to step down to these layers, and,.... cornices are definitely getting larger these days. Lowered freezing levels are good for overnight recovery of the snowpack below 1700 metres. Daytime warming could produce loose, wet avalanches below 1700m especially on steep solar aspects.
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.