Avalanche Forecast

Moderate - Uncertainty is due to extremely variable snowpack conditions reported through the region.

Sunday night: Mostly cloudy, isolated flurries with a trace of accumulation, light southwest winds, alpine temperatures -5 C and freezing levels near 1000 m.

Monday: Cloudy with isolated flurries with 1-3 cm of accumulation, moderate southwest winds, alpine high temperatures around -3 C, with freezing levels around 800 m.

Tuesday: Cloudy, 5-10 cm of snow, moderate to strong southwest winds, alpine high temperatures around -1 C, with freezing levels around 1000 m.

Wednesday: Cloudy, 5-10 cm of snow, moderate to strong southwest winds, alpine high temperatures near 0 C with freezing levels rising to 1500 m.

Avalanche activity has decreased since the widespread avalanche cycle a week ago, and no recent activity has been reported. During that cycle, avalanches were reported to be running to valley-bottom in the north of the region, failing on deeply buried weak layers. See this MIN report of an avalanche involvement from last week for an example of this avalanche problem.

The possibility for large human-triggered persistent slab avalanches remains a concern at higher elevations in the northern part of the region (e.g., Duffey, Hurley, etc.), especially as recently formed wind slabs create the potential for small avalanches to step-down to these layers. These persistent weak layers continue to produce concerning snowpack test results and are expected to heal slowly. 

Snowpack variability between the northern and southern parts of the region is significant. 

In the north (e.g. Duffey, Hurley) 5-15 cm of recent snow has been drifted into shallow, reactive wind slabs on leeward features at upper elevations. Below the surface, a weak layer from late November (down 30-70 cm), composed of sugary faceted grains and hard melt-freeze crust, is a recipe for large and destructive avalanches. It presents a persistent slab problem that may persist for weeks to months. This persistent weak layer is largely absent in the south of the region.

• Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
• Uncertainty is best managed through conservative terrain choices at this time.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.