Avalanche Forecast

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

The stormy conditions continue with another 10-25cm of snowfall forecast Sunday overnight and Monday. Amounts will be greatest along the coast and taper substantially as you move inland. Alpine winds should be moderate to strong from the southwest and freezing levels should be around 1200m. The last weak storm pulse is forecast to bring another 10-15cm for Monday overnight or Tuesday morning. By Tuesday afternoon the storm system should clear out as a ridge of high pressure builds. Freezing levels should drop to valley bottom by Tuesday night and alpine winds should die off. Mostly sunny conditions are expected for Wednesday.

On Saturday, numerous size 1 soft slab avalanches were reported in the region. Isolated natural wind slab avalanches were reported from steep leeward features at treeline and in the alpine. These appear to be mainly north through east aspects. Ski-cutting was producing similar results from wind-loaded features at treeline and in the alpine. Slab depths varied from 10 to 40cm thick and many were running on the recently buried mid-January surface hoar layer. On Friday, a few natural storm slab avalanches size 2-2.5 were reported from a variety of aspects. These varied in thickness from 15-45cm and were releasing on the early-January surface hoar layer. Natural and human-triggered avalanches are expected to increase in size and reactivity as the storm continues.

15-30cm of recent storm snow has buried the newest layer of surface hoar (Jan 15) which is reported to extend into the alpine. As you move inland, cumulative storm snow amounts from the first half of January taper off substantially. There are two other weak layers in the upper snowpack which are still reactive. The Jan 11 surface hoar layer is down 40-70cm and the early-January surface hoar layer is down 50-80cm. We are seeing the likelihood of triggering these layers to be going down but the resulting size and destructive potential of avalanches on these layers is increasing. Below these layers, the mid and lower snowpack is generally strong. At lower treeline elevations, warm temperatures and rain/wet snow have saturated the upper snowpack. Moist surface snow has recently been reported as high as 1950m. At higher elevations, moderate to strong southwest winds continue to load lee features at treeline and in the alpine.