Beware of wind-loaded and sun-exposed slopes where the recent storm snow has settled into touchy slabs.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Expect continued cold and dry conditions for Wednesday, Thursday and Friday with the chance of some cloud late Thursday into Friday. Winds should remain light and variable for Wednesday and Thursday, but pick up to strong northerlies on Friday. Alpine temperatures are expected to remain in the -10 to -20 range with a weak inversion on Wednesday, but significant cooling for Friday.
Avalanche Summary
Reports from Monday include a few Size 1-2 naturally occurring storm slab avalanches on west through southwest aspects in the alpine. On Sunday, a small cornice was human-triggered and loose snow avalanches were noted in steeper terrain. Expect the recent storm snow to be reactive to light triggers in areas where it has settled into a cohesive slab, such as lee slopes near ridgecrests and terrain breaks and sun-exposed slopes.
Snowpack Summary
Around 20cm of low density snow recently buried the previous variable snow surface, which includes hard wind pressed or scoured areas, old wind slabs, weak faceted snow, or small surface hoar. The cold temperatures appear to be preserving the old (now buried) wind slabs from the end of last week and they still may be reactive to human triggering in isolated areas. In high elevation terrain, moderate southwest winds over the weekend may have redistributed some of the new storm snow and soft slabs may exist in immediate leeward features. The widespread mid-November crust is typically down 1-2m in the snowpack. Recent snowpack and explosive tests have shown the crust to be unreactive, but it could remain a problem in shallow alpine start zones.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.