Fog blankets Calif. I-5 'indefinitely,' forecasters warn drivers to use caution

"After recent rains drenched the Central Valley, dense fog is now rolling in through the holiday weekend. Murky conditions blanketed the region Friday morning, earning a dense-fog advisory through 10 a.m. due to visibility of less than a quarter of a mile. The most affected areas included Bakersfield, Delano and the southern portion of Interstate 5, Stephen McCoy, a meteorologist with the National Weather Service, told SFGATE."

"Though the advisory lifted later on Friday morning, McCoy said the thick fog is likely to reappear because there aren't any large-scale weather patterns in the forecast that would change the conditions. He described the weather pattern as "benign" because the low clouds are expected to stick around, causing more fog overnight and in the early mornings. "Just because we get some clearing throughout the day, doesn't mean it won't be coming back the next day," McCoy said."

"The fog also is lingering over the region because above-average rainfall from earlier this season caused a large amount of moisture at the surface, he said. The moisture is evaporating from the ground and condensing. "Because we're surrounded on three sides by the mountains that air doesn't really go anywhere," McCoy said. "There's no place for it to go and so it just kind of sticks around in this area. That kind of creates our fog and our low cloud conditions that we're currently seeing.""

Dense fog formed across the Central Valley after recent heavy rains, producing a dense-fog advisory when visibility dropped below a quarter mile. Bakersfield, Delano and the southern portion of Interstate 5 experienced the worst conditions, while areas north near Fresno saw visibility between one-half and one mile. The largest fog field stretched roughly 60 miles between the coastal range and the Sierra Nevada, with a 30-by-50-mile pocket from the Grapevine to Bakersfield along Highway 99. A benign large-scale pattern and abundant surface moisture from above-average rainfall allow low clouds and fog to persist overnight and into mornings, as surrounding mountains trap the air. Drivers should exercise caution during foggy morning commutes.

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