North Columbia

Cranking ridgetop winds will likely build fresh and touchy wind slabs.

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Sunday

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.

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.

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.