The National Weather Service has issued a Dense Fog Advisory for portions of the Mother Lode, which is in effect until 10 AM this morning.
Visibilities are below one quarter mile in many foothill locations and in some areas the visibility is down to nearly zero.
Morning commuters are likely to be impacted by dangerous drops in visibility and other commuters slowing down in areas of reduced visibility.
Clearing skies and cool overnight temperatures allowed the fog to form over many locations.
Three local mountain passes remain closed this morning, due to snow in the Sierra Nevada earlier this week. Tioga Pass (Hwy 120) Sonora Pass (Hwy 108) and Ebbetts Pass (Hwy 4) are all closed.