Spring sun could push the hazard higher than forecast on solar aspects. Keep an eye on cornice hazards
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Synopsis: A northwesterly flow will bring cool and unsettled weather for the next few days .Tonight: Cloudy, trace to 5 cm of precipitation, freezing level at valley bottom, winds light from the south east.Friday: Cloudy, no precipitation in the forecast, freezing level at valley bottom, light south east ridge top winds.Saturday: Cloudy with snow, 5 to 10cm of precipitation, freezing level at valley bottom, ridge top winds, light to moderate from the south east.Sunday: Sunny with cloudy periods, No precipitation in the forecast, freezing level around 600 metres, light ridge top winds from the north.
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
10 to 20cm of overnight snow combined with winds have produced yet another set of wind slabs overlying the storm slabs at tree line and above. The storm slab, however, 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. Moderate to strong SW winds have formed wind slabs on lee slopesBelow the storm snow, the upper 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 storm, 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.