Avalanche Forecast

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack. We are confident about the possible sizes of avalanches, should one release; what is less certain is the likelihood of triggering.

Friday night: Mostly cloudy, light west wind, temperatures near -8 C.

Saturday: Mostly cloudy with scattered flurries developing later in the day and bringing 1-3 cm of new snow by morning. Moderate southwest winds, alpine high temperatures around -6 C in the north of the region, closer to -3 C in the south. 

Sunday: A mix of sun and cloud. Light southwest winds, alpine high temperatures around -2 C and freezing level rising to 900 meters.

Monday: Mix of sun and cloud. Light to moderate southwest winds, alpine high temperatures around -3 C.

Avalanche observations have been on a declining trend since the widespread avalanche cycle observed last weekend. 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 weekend for an example of this avalanche problem.

The possibility for large human-triggered persistent slab avalanches remains a serious concern at higher elevations in the northern half of the region (e.g., Duffey, Hurley, etc.) as these persistent weak layers continue to produce concerning snowpack test results and are expected to heal slowly. 

5-10 cm of new snow has fallen on a weak interface with moderate west winds forming shallow, touchy wind slabs on lee features in the alpine. 

Below the surface, the storm at the end of last week brought over 120 cm of snow to the south of the region and about 40 cm to the north of the region. This snow is gaining strength, but conditions beneath this layer vary dramatically and, in some areas, highly problematic.

In the north of the region, the above-mentioned storm snow brought a critical load to a now 30-70 cm-deep weak layer from late November composed of sugary faceted grains and hard melt-freeze crust. This structure is a recipe for large and destructive avalanches and a problem that may persist for weeks to months. This problematic layer is largely absent in the south of the region.

• Uncertainty is best managed through conservative terrain choices at this time.
• Persistent slabs have potential to pull back to lower angle terrain.
• Avoid steep convexities or areas with a thin, rocky, or variable snowpack.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.