The forecast new snow and wind should increase the avalanche danger. If the storm comes early the danger may be high by Friday afternoon.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Friday
Weather Forecast
Overnight and Friday: Freezing level dropping down to about 600 metres overnight. Snow starting in the early morning near the coast and moving inland as a warm front moves across the region. Expect 15-20 cm of snow near the coast, and 10-15 cm inland during the day. Southwest winds should build to strong values by the afternoon and freezing levels should rise to about 1500 metres.Saturday: A trailing cold front should bring another 15-20 cm of snow to near coastal areas and 5-10 cm further inland by morning. Winds should slow to moderate Southwest during the day as snow continues. Freezing level rising to about 1500 metres during the day.Sunday: Snow ending overnight or early morning. Light Southerly winds and freezing levels rising to about 1300 metres.
Avalanche Summary
No new reports of avalanches.
Snowpack Summary
The recent snow is expected to settle and bond to the mix of old surface crusts and wind slabs with daytime warming and overnight freezing levels dropping down to near valley bottoms. The forecast new snow and strong Southwest winds are expected to develop new storm slabs over the next few days that may release down to the old surface of melt-freeze crusts and/or where facets are sitting on old wind slabs. The added load of storm snow or storm slab avalanches in motion may trigger the March persistent weak layer. The early-March crust/facet layer is down about 100-150 cm and the early February layer is now down close to 200 cm.
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.