Breaking Dense Fog Advisory: How This Morning’s Near-Zero Visibility Could Disrupt Your Commute

A widespread Dense Fog Advisory remains in effect this morning across several states, reducing visibility to a quarter-mile or less during the critical pre-dawn and rush-hour commute. The National Weather Service (NWS) warns that thick fog stretches from the Northern Rockies through the Mississippi Valley and parts of the Gulf Coast. In eastern Idaho—including Pocatello, Idaho Falls and surrounding highways—visibility has periodically dropped to near zero; the NWS office there has extended its advisory until noon MST today. Farther east, forecasters in Des Moines highlight “areas of fog, some dense,” with patchy freezing mist possible on untreated bridges and overpasses before temperatures climb later this afternoon. Similar low-visibility alerts blanket stretches of Louisiana and Mississippi, where moist Gulf air meets overnight radiational cooling. Travel impacts • Interstates 15, 84 and 90 in the northern tier, along with I-55 and I-10 in the South, are reporting slowed traffic and sporadic lane closures while road crews post reduced-speed advisories. • Regional airports from Boise to Baton Rouge are experiencing departure holds of 15–45 minutes; passengers should confirm status before leaving home. • School districts in at least four counties have announced two-hour delays; check local announcements if you have morning drop-offs. Why the fog is so thick Clear skies overnight allowed ground temperatures to fall rapidly, saturating the near-surface layer once dew points were reached. Light winds prevented mixing, so moisture pooled close to the surface. With sunrise not until after 7 a.m. in many of the affected zones, the dense layer is expected to persist through mid-morning before gradual improvement. Safety tips you can use now 1. Slow down and allow extra braking distance; wet roads and sudden “wall-of-fog” pockets can appear with little warning. 2. Use low-beam headlights or fog lights—never high beams, which reflect off the moisture droplets and worsen glare. 3. Leave plenty of following space; tail-light clustering is common and can trigger chain-reaction crashes. 4. If visibility drops to zero, pull completely off the roadway, turn on hazard lights and wait until conditions improve. 5. Air travelers should sign up for text alerts from their airline and consider arriving earlier than usual to navigate longer security lines caused by flight bunching. When will it lift? Meteorologists anticipate a gradual dissipation between 10 a.m. and noon local time as solar heating promotes vertical mixing. However, valleys, river bottoms and low-lying coastal zones could see patchy fog redevelop overnight, so commuters should stay alert for another advisory heading into Friday. Looking ahead A weak frontal boundary sliding in from the Pacific Northwest tonight will introduce a light breeze across the northern Plains, likely scouring out residual moisture there. Meanwhile, deep southerly flow over the Gulf states will keep humidity levels high; residents from Houston to Mobile may wake up to another blanket of fog tomorrow. Bottom line If you must travel this morning, budget extra time, drive defensively and stay tuned to updated NWS statements on your NOAA Weather Radio, mobile app or local news outlets. The fog will lift—but patience and caution now can prevent accidents and delays once you hit the road.