Cranking ridgetop winds will likely build fresh and touchy wind slabs.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Sunday
Weather Forecast
A series of Pacific frontal systems will hit the Interior region starting tonight and continue through next week. Each system will be a bit stronger bringing moderate to heavy snow amounts and strong winds. Sunday: Cloudy, alpine temperatures -9 with West winds 30-40 km/h. New snow 5-10 cm.Monday: Snow 15-25 cm with alpine temperatures near -7 and ridgetop winds southwest 30-70 km/h.Tuesday: Snow 5-10 cm with alpine temperatures -8 and ridgetop winds light from the southwest.
Avalanche Summary
On Friday, isolated natural and rider triggered wind slabs and sluffing up to size 1.5 were reported. The avalanche danger will rise with new wind slab problems being the primary concern Sunday and storm slabs building on Monday.
Snowpack Summary
Recent wind has formed isolated wind slabs on a variety of aspects in the alpine. The surface snow has been faceting due to the cold temperatures, and some surface hoar has been developing in sheltered locations. The mid-pack has been reported to be well settled above a crust that was buried in mid-November. This crust is be buried 90-160cm deep, depending on elevation and previous exposure to winds. Snowpack tests on the crust have shown variable results from sudden to no result. If you dig down to the crust, watch for facets (sugary crystals) developing above and below. This may provide a hard surface with a weak sliding layer in the future.
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.