Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Sunday: Northwest flows aloft will bring some snowfall accumulations. Snow amounts 5-10 cm accompanied by moderate ridgetop winds from the West. Alpine temperatures near -6.0 and freezing levels at 800 m. Monday: A low pressure system over Gulf of Alaska will move onto the north coast, sliding South bringing light precipitation. Snow amounts near 5cm with moderate NW ridgetop winds. Alpine temperatures near -6 and freezing levels hovering around 800 m. Tuesday: Light-Moderate snowfall amounts expected. Alpine temperatures near -3.0. Ridgetop winds will shift out of the West in the light ranges.
Avalanche Summary
On Friday, reports of size 1-2 natural slab avalanches occurred. Explosive avalanche control produced numerous size 1-2 slab avalanches on NW-NE aspects from 1800-2200 m. Most releases were within the old storm snow.
Snowpack Summary
New snow accumulations around 25 cm overlie a variety of old surfaces including hard wind slabs, thin and thick crusts and large surface hoar crystals which can be found in sheltered areas below treeline. Recent winds have shifted snow into soft and hard slabs anywhere from 25-40 cm thick on lee slopes. The early January surface hoar layer is buried down 40-80 cm and seems to be gaining strength. Reports indicate that this layer is mainly unreactive, and would require a large trigger to set it off. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in unsupported, shallow, rocky terrain where more faceting has taken place.
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.