Here’s why it’s been so foggy on the Coast lately

Fog surrounds birds as they rest along the beach in Biloxi in 2016.
Fog surrounds birds as they rest along the beach in Biloxi in 2016. Sun Herald file

The spell is lifting and the misty gray clouds of fog cursing the Coast with limited visibility and seasonal affective disorder should start to clear this weekend.

A cold front expected Saturday evening should clear things up, but it’s also expected to bring a line of storms that could put a damper on Mardi Gras festivities.

Several parades in New Orleans have been moved up or rescheduled, but the Coast’s only night parade, Carnival Association of Long Beach, says it will roll at 6 p.m. rain or shine.

There could be brief heavy downpours, gusty winds and lighting between 6-10 p.m. depending on how fast the cold front moves, said Phil Grigsby, forecaster at the weather service’s New Orleans office.

The front will bring dry air from the northwest and clear out the heavy fog that’s been hanging around by Saturday evening, he said.

But why has it been so foggy?

Grigsby said this time of year, between December and March, is typically fog season for the Gulf Coast. But he agreed the frequency duration of the fog spells seems high, although it’s hard to say for certain because the National Weather Service doesn’t track fog advisories over time.

But just in February, there’s been 11 days with dense fog advisories.

“This is kind of typical as far as the time of year for it to occur, but the duration of the events that we’ve been having is a little unusual,” he said, especially for those south of Interstate 10.

The reason? Warmer-than-average weather.

“We’re running a good 10 to 15 degrees above normal as far as temperatures go, he said.

“It’s almost like an April or May type weather pattern right now, as opposed to what we would typically see in February.”

And because the few cold snaps we have had cooled water temperatures down, that warm air causes fog.

When you get the warmer, more humid air to move over that cooler water, the air temperature cools and that causes it to condense down and turn into fog and then the south winds advect the fog, or push the fog onshore,” he said.

The good news is the cold front will drop temperatures back down closer to average, and a northeastern wind through most of the week means the Coast should be mostly fog-free.

There’s a 50 percent chance of rain Saturday, and the low is expected to be in the upper 50s, dropping into the mid- to low 40s by Sunday and Monday nights.

Temperatures should start to warm Tuesday with a chance of showers returning.

Lauren Walck has been in journalism on the Gulf Coast for 10 years, and she’s the Sun Herald’s senior news editor and a regional growth specialist. She is a native of Mobile, Alabama, and an alumna of Louisiana State University.
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