Why super fog is continuing to create dangerous driving conditions in Louisiana

Relentless drought conditions fueling the persistence of marsh fires burning in parts of southeastern Louisiana are causing a continuation of super fog events on regional highways during peak commute times.

Interstate 10 and Highway 11 near New Orleans were closed in the morning on Tuesday and Wednesday due to poor visibility on the major thruways, causing dangerous driving conditions.

A dense fog advisory was issued for much of eastern Louisiana on Wednesday morning, from Baton Rouge to Slidell, also extending into eastern portions of New Orleans. Visibility ranged from just .25 miles in Slidell, in northeast Louisiana, about 7 miles in Baton Rouge and 2.5 miles in New Orleans, according to the National Weather Service.

While there were no accidents on Wednesday morning in the region, Tuesday saw several crashes and at least one fatality, according to Louisiana State Police.

Super fog conditions have been ongoing since Oct. 23, after low visibility that day caused at least eight fatalities and dozens of injuries in pileups on Interstate 55 near New Orleans.

The intense fogs typically form as marsh fires burning in the region mixes with the moisture released from smoldering damp organic material, such as brush, leaves and trees, and condensed water vapor, according to the NWS.

Areas of smoke will continue to be possible in the region as various marsh fires continue to burn. The potential for dangerous areas of dense fog and some super fog will continue to be possible until the marsh fires can be fully extinguished, removing the smoke from the surrounding air.

The location of the densest fog and most dangerous conditions vary day to day. On Wednesday morning, the worst of the fog was on the eastern side of Lake Pontchartrain, northeast of downtown New Orleans, including stretches of I-10 and also portions of I-12. Visibilities were near-zero in some spots.

Super fog can be especially dangerous when they develop near and over highways. The localized nature of the weather phenomenon means that visibility conditions can worsen rapidly within a very short distance, which can lead to a hazardous combination of sudden low to near-zero visibility and vehicles traveling at a high speed on a highway.

The very limited visibility then hinders a driver's ability to react to changing conditions on a roadway.

While morning fog is not uncommon in the region this time of the year, this area and nearly the entire state of Louisiana continues to battle relentless drought conditions. More than 67% of the state remains under "exceptional drought" conditions, the most concerning drought category, according to the U.S. Drought Monitor, which is elevating fire danger.

By Friday and into the upcoming weekend, rain is in the forecast and could help suppress the marsh fires in the area, leading to short-term relief of super fog. However, foggy conditions will persist but not be as intense.

The rain also won't end the relentless drought, so if additional marsh fires spark in the coming weeks, super fog could be a concern once again.