Variable snow amounts are forecasted across the region, with the most expected on the eastern slopes. Treat the hazard as higher if local snow amounts are substantially more than forecasted.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
THURSDAY: Cloudy with snowfall, accumulation 10 to 20 cm, light westerly winds, alpine temperature -4 C, freezing level 1400 m.FRIDAY: Cloudy with light snowfall, accumulation 5 cm, light easterly winds, alpine temperature -6 C, freezing level 1400 m.SATURDAY: Cloudy with snowfall, accumulation 10 to 15 cm, light to moderate northeasterly winds, alpine temperature -8 C, freezing level 1000 m.
Avalanche Summary
Widespread loose wet avalanches were noted on solar aspects to size 2 on Tuesday. There was evidence of slab activity from sometime over the past week. Some of the slabs stepped down to deep basal weaknesses.
Snowpack Summary
New snow will fall on a thick melt-freeze crust that exists on all aspects from recent warm temperatures and rain, except for possibly high elevation north. On shady aspects at high elevations, new snow will likely fall on lingering wind slabs in lee features and loose dry in sheltered features.A weak layer of surface hoar buried mid-February exists in parts of the region around 50 to 80 cm deep. The lower snowpack is weak with a combination of crusts and facets near the bottom of the snowpack that are widespread.
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.