Regions
Northwest Coastal.
Another 20-30 cm, strong-extreme winds and warmer temperatures create the perfect recipe for High Danger and widespread natural avalanche activity.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Wednesday night-Thursday: snow amounts 15-30 cm with light winds gusting extreme from the SW. Alpine temperatures near -1 and freezing levels 700 m. Friday: Periods of snow 5-10 cm. Ridgetop winds light gusting to 65 km/hr from the SW. Alpine high of -5 and freezing levels falling to 400 m. Saturday: Mostly cloudy with sunny periods. Snow amounts 3-8 cm and ridgetop winds generally light. Alpine temperatures high of -5 and freezing levels 300 m.
Avalanche Summary
On Tuesday, explosive results saw several size 1 slab avalanches which initiated within the recent storm snow. Loose dry sluffing from steeper terrain features were also noted. More snow and strong winds will continue to build reactive storm slab avalanches.
Snowpack Summary
Recent storm snow 20-50 cm has buried a variety of old snow surfaces including surface hoar, facets, crusts, stiff wind slab and a melt/ freeze crust below 1600 m. The deeper storm snow amounts exist in the Shames/ Terrace area with less accumulations further North and East. The new snow will likely have a poor bond to these older surfaces. Deeper in the snowpack 60-90 cm down a layer of surface hoar was buried on February 10th at tree line elevations and continues to be reactive in some recent snowpack tests. Below this layer, the snowpack is generally settled and strong with the exception in shallow snowpack areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern.
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.