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 -11 with West winds 20-50 km/h. New snow 5-10 cm.Monday: Snow 15-25 cm with alpine temperatures near -11 and ridgetop winds southwest 30-70 km/h.Tuesday: Snow 5-10 cm with alpine temperatures -10 and ridgetop winds southwest 20-40km/h.
Avalanche Summary
On Friday, isolated wind slabs and sluffing up to size 1.5 were reported. With increased winds on Sunday new wind slab problems will be the primary concern. Storm slabs will likely build on Monday.
Snowpack Summary
Due to recent cold and clear conditions a variety of surface snow exists from faceted (sugary) crystals to surface hoar crystals up to 8 mm in size. Forecast new snow will likely have a poor bond to these surfaces. Variable wind effect has created wind slabs in isolated areas at upper elevations. A buried surface hoar layer may exist down 30-40cm. The depth of the mid-November crust is also variable across the region. Reports have the crust down between 100-200 cm and snowpack tests have produced a variety of results from moderate and sudden to hard and resistant, and in some cases no result. If you dig down to the crust, watch for facets developing above and/or below. This may provide a weak layer above a smooth sliding surface 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.