Weather Forecast
Saturday: Moderate SW ridge top winds diminishing after sunset. Occasional flurries. 1500m temp: -12 Freezing level: SurfaceSunday: Moderate SW ridge top winds. 1500m temp -9. Isolated flurries. Freezing Level: SurfaceMonday: Light E-SE ridgetop winds. Treeline temp -16. No snow. Freezing Level: Surface
Avalanche Summary
We're starting to see the effect of the big winds midweek. We're getting observations from across the region of a natural avalanche cycle to size 2 in the alpine. These avalanches are coming from steep terrain below ridgetop.
Snowpack Summary
Winds picked up mid week and moved a lot of storm snow around, especially in the upper treeline & alpine elevations. The recent storm deposited 25-50 cm in the North of the region near Golden, and 30-80 cm further South near the Purcell Wilderness Conservancy. Moderate to strong winds Wednesday/Thursday created windslabs capable of producing size 2 avalanches at and above treeline. Windslab distribution and size is wildly inconsistent across the region, but it feels like they grow in size as you travel further south. There is some talk about a December 16th surface hoar layer, but it's distribution is *very* spotty.
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.