Avalanche Forecast

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

Tuesday: Cloudy, 10-20 cm of snow, moderate to strong southwest winds, alpine high temperatures around -2 C, with freezing levels around 1400 m.

Wednesday: Cloudy, 20-30 cm of snow, moderate southwest winds, alpine high temperatures near 0 C with freezing levels around 1400 m.

Thursday: Partly cloudy, isolated flurries with trace accumulations, light variable winds, alpine high temperatures around -7 C.

The likelihood of triggering avalanches increases with the incoming storm.

Avalanche activity has diminished 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 and 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 newly formed wind slabs create the potential for smaller avalanches to step-down to these layers. 

The storm brings new snow for strong southwest winds to drift into touchy wind slabs in exposed areas near and above tree line. 

The snowpack below varies significantly between the northern and southern parts of the region. In the north (e.g. Duffey, Hurley) 5-15 cm of snow from the weekend has been drifted onto leeward features at upper elevations. Elsewhere this recent snow remains unconsolidated or was warmed as product of solar radiation and warm air temperatures. The interface below it may present as surface hoar in many sheltered locations. 

The upper snowpack consists of around 30-70 cm of snow that overlies a weak layer from late November composed of sugary faceted grains and hard melt-freeze crust. This presents a persistent slab problem that may persist for weeks to months with the potential to produce large and destructive avalanches. This persistent weak layer is largely absent in the south of the region.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Watch for avalanche hazard to increase throughout the day.