Short term forecast from the National Weather Service

LOW BASED CLOUDS BANKED UP ALONG THE MOTHER LODE FOOTHILLS AND
HIGHER SIERRA SLOPES ARE RESULTING IN A LOCALLY DENSE FOG.
VISIBILITIES HAVE BEEN REDUCED TO LESS THAN A QUARTER OF A MILE IN
THESE REGIONS... INCLUDING GRASS VALLEY AND BLUE CANYON.

MOTORISTS ARE ADVISED TO SLOW DOWN AND KEEP HEADLIGHTS ON WHEN
ENTERING AREAS OF HEAVY FOG. VISIBILITIES WILL INCREASE AS
CLOUDBANK LIFTS LATE THIS MORNING.