Avalanche Forecast

Fair - Timing of incoming weather systems is uncertain

The sub-tropical storm system continues to produce similar weather conditions on Thursday. Freezing levels will be around 2000m, alpine winds should remain strong, and we can expect another 5-15mm of precipitation. Things start to change on Friday as freezing levels should drop below 1500m and alpine winds ease during the day. Lingering precipitation is expected on Friday with amounts around 2-4mm. A ridge of high pressure is expected to begin to build on Saturday resulting in a mix of sun and cloud. Freezing levels are expected to be back down near valley bottom and winds should be calm or light.

Reports from Wednesday includes natural loose wet avalanches up to size 1.5 from steep terrain up to 2200m and explosive triggered slab avalanches up to size 2.5. These slabs are typically around 20cm thick. I expect as more snow accumulates in the alpine and the slab gets thicker, we should start seeing natural storm slab avalanches, especially from the more wind loaded areas.

Rain to high elevations is expected to be saturating the upper snowpack. A wet snow surface is expected up to 2000m elevation and moist snow to around 2400m. Strong winds are loading leeward features in the alpine. Below the new storm snow may be a layer of surface hoar which was buried on Dec 5. Another 15-20cm below this you may find a hard rain crust. In the Golden area this crust exists up to around 1600m, whereas in the south it is up to 2000m or higher. Deep in the snowpack you may find the mid-November weak layer (surface hoar, facets, and/or a crust) and/or a faceted rain crust from early November. The reactivity of these layers may be slowly diminishing, but they still warrant cautious consideration. In some areas that already avalanched, the new storm snow may be sitting on a thick layer of facets that are sitting on the ground.