Urgent Dense Fog Advisory Issued—Expect Hazardous Commutes and Flight Delays

Early morning commuters across large portions of the Gulf Coast, Florida Peninsula, Central Valley of California and the Upper Midwest awoke Friday to pea-soup conditions after the National Weather Service (NWS) blanketed more than a dozen states with Dense Fog Advisories. Visibility routinely dropped below ¼ mile from South Texas beaches through Louisiana bayous, the I-4 corridor in Florida and as far north as International Falls, MN. Why the widespread haze A stagnant high-pressure ridge, clear overnight skies and abundant low-level moisture set the stage for rapid radiational cooling. As surface temperatures fell to the dew point, water droplets condensed into a thick ground-hugging cloud layer. Light winds then allowed the fog to expand over land and adjacent near-shore waters, prompting simultaneous Marine Dense Fog Advisories from Tampa Bay to Galveston Bay. In California’s San Joaquin Valley—the nation’s “fog bowl” this time of year—NWS Hanford warns the advisory may persist through Saturday morning, threatening zero-visibility “Tule fog” along I-5 and SR-99. Impacts on travel and commerce • Highways: Florida Highway Patrol reported multiple minor crashes on I-75 near Sarasota before sunrise; speeds were reduced to 45 mph on long stretches of I-10 east of Houston. • Air: Tampa International listed arrival delays averaging 40 minutes, while patchy fog at Houston Hobby caused periodic ground stops. • Marine: Operators on Galveston Bay, Tampa Bay and Mobile Bay were urged to sound fog signals and use radar after visibilities fell below one nautical mile. When will it lift? Most coastal and interior sections of Florida, Alabama and Texas should see the fog erode between 9 a.m. and noon local time as solar heating mixes the boundary layer; however, pockets in low-lying river valleys could linger longer. Central Valley motorists may contend with dense fog again overnight as similar radiational conditions redevelop. Safety checklist for dense fog 1. Slow to 30-40 mph or lower; allow at least five seconds of following distance. 2. Use low-beam headlights or fog lights—never high beams. 3. Avoid sudden lane changes; use pavement reflectors as lane guides. 4. At intersections, roll down windows to listen for oncoming traffic you cannot see. 5. Boaters should run navigation lights continuously and monitor marine VHF channel 16. What’s next A weak cold front sliding through the Southern Plains late Friday could introduce drier air and gradually end the Gulf Coast fog cycle this weekend. In Florida, moisture returns Monday ahead of another round of sea fog, so drivers should stay alert to renewed advisories. Bottom line If your Friday plans involve pre-dawn driving, early flights or boating along the Gulf Coast or Central Valley, build in extra time and keep those low beams on until the sun can do its work. Stay tuned to your local NWS office and trusted outlets such as the Tampa Bay Times for real-time updates.