South Columbia

Snow amounts will gradually accumulate over a variety of potential weak layers in the coming days. Updated 8:30am Dec18

Moderate - Intensity of incoming weather systems is uncertain on Tuesday

MONDAY: Snow Sunday night into Monday accumulations 10-20cm then cloudy with scattered flurries / Light to moderate northwest / Alpine temperature -9 TUESDAY: Periods of snow accumulations 15-20cm / Light to moderate southeast wind / Alpine temperature -12 WEDNESDAY: Cloudy with isolated flurries, accumulation 5cm / Light north wind / Alpine temperature -15

Recent reports of avalanche activity are limited to a few very soft slab and/or loose snow avalanches to size 1.5 on northerly aspects in the alpine. As snow amounts begin to accumulate in the coming days expect to see an increase in avalanche activity.

The 25-40 cm of new snow accumulating Friday through Sunday evening now sits on a wide variety of old surfaces including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. As the snow load builds and slab properties develop, it will be important to monitor how the new snow is bonding to the old surfaces. Most concerning would be areas that have surface hoar sitting on top of a hard crust. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 60-80cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it. Snowpack depth decreases rapidly below tree line. Look out for early season hazards such as rocks, stumps, and open creeks.