SAN JUAN MOUNTAIN WEATHER: 2/8/13 UPDATE

07 Feb SAN JUAN MOUNTAIN WEATHER: 2/8/13 UPDATE

Very temporary high pressure is bringing sunny, dry conditions to our forecast area today (Thursday) as the Gulf of Alaska storm currently along the Pacific NW coast swirls inland. Two models show the strong closed low invading the Great Basin Friday afternoon while flow aloft turns SW Friday morning with the nose of the upper jet moving into southeast Utah and western Colorado Friday afternoon.

Anticipate snow and mixed snow/rain in the valleys by Friday afternoon/evening and probably some thunderstorms. Precipitation looks limited early in the storm, but a tail of warm Pacific moisture may get entrained by the digging low that contains most of the moisture. The storm could produce high precip rates late Friday because of orographic lift and storm energy rounding the bottom of the trough then ejecting north east Saturday morning. Anticipate decent snowfall with strong winds causing blowing snow Friday evening into Saturday. Elevations above 11,000′  on favored SW aspects could receive two feet of snow from this storm.

Strong southwest orographic flow and jet dynamics Friday night will favor south facing slopes then shift to north facing slopes Saturday evening as the low moves east and the backside of the trough brings northwest flow to the front of the San Juans. Also a secondary trough will move down the backside of the  low as it moves into the plains bringing good moisture and unstable cold air  fueling snowfall for the NNW San Juans Sunday through Monday afternoon.