The annual wintertime fog in the Central Valley has been especially dense this year, creating a major hazard for roadway travelers and resulting in Clovis Unified’s first foggy day bus schedule in more than two decades.
What’s causing the extra persistent haze?
Foggy conditions have lingered longer throughout the day because of extra moisture left behind from prior storm systems, said Brian Ochs, a meteorologist at the National Weather Service’s Hanford office.
Ochs said an inversion layer situated above the Valley is keeping the weather stable — allowing the foggy weather to thrive without wind or rain to break it up.
While temperatures typically decrease with elevation, an inversion layer will result in temperatures getting warmer until about 4,000 feet, Ochs said. This stable, high-pressure system both traps the moisture and keeps weather disturbances at bay.
The Valley can expect the fog to linger until at least the end of this week.
With the hazy conditions, roadway travel has been particularly hazardous. A 17-vehicle pileup on Highway 99 in Fresno resulted in one fatality last weekend. This week, a pedestrian was struck in a hit-and-run in thick fog, and a pickup driver died in a crash with a big rig.