Extreme rainfall rates overwhelming New Orleans' drainage systems, agency says (2024)

A flash flood emergency is overwhelming New Orleans' complex network of pumps and other "aged" floodwater-mitigating infrastructure, according to the agency that manages it.

Roughly 4 inches of rain and exceptional rainfall rates nearing 5 inches per hour were reported at some pumping stations. The extreme rainfall rates are surpassing what the pumps can usually handle, Sewerage and Water Board of New Orleans officials told CNN.

Because parts of the area are below sea level, the city has to rely on a complex pumping system to prevent severe flooding. While some drainage infrastructure relies on gravity, most are fueled by electricity-powered pumps. During heavy rainfall, the pumps can get overwhelmed to the point they can no longer remove water fast enough, causing floodwater to build.

Seven drainage pumps in New Orleans were also out of service. Two of the pumps are out of service due to routine maintenance, while the rest are either out for refurbishment or out due to issues with the electric motor, the water board said.

One of the power generators for the pumps, Turbine 4, is also unavailable, according to SWBNO.

"We have one of the most active, complex, and aged drainage systems in the world in a city that sits half below sea level," Birch said. "Our thoughts are with our surrounding neighbors in the region who are experiencing more intense rain, high winds, and tornadoes."

More of the New Orleans metro is at risk for life-threatening flash flooding as torrential rainfall deluges the area.

An additional flash flood emergency was issued Wednesday afternoon for areas just west and south of New Orleans.

This new warning includes over 500,000 people and lasts until 4:45 p.m. ET (3:45 p.m. CT). In total, over 900,000 people in New Orleans and surrounding areas are under flash flood emergencies.

“Flash flooding is already occurring,” and damage could be catastrophic, the National Weather Service warned Wednesday afternoon.

Up to 3 inches of additional rain is possible in the heaviest storms before precipitation eases later this afternoon.

At least 29 flights have been canceled today at New Orleans International Airport while another 82 have been delayed, according to the flight-tracking data company FlightAware.

The airport tops the list for delays and cancelations today, according to FlightAware.

Parts of Louisiana are experiencing severe weather. In Slidell, multiple people have been transported to a hospital after a possible tornado hit the town and police there are working on rescuing people.

Multiple people have been transported to a hospital after a possible tornado hit the town of Slidell in Louisiana, according to St. Tammany Parish.

There are currently two open shelters in the parish, located at John Slidell Park gym and the recreation center in Lacombe, theparishsaid.

The Slidell Police Department in Louisiana is working on rescuing people after a possible tornado hit the area on Wednesday, according to Slidell public information officer Daniel Seuzeneau.

According to Seuzeneau, the police department rescued about 50 people from an apartment complex. Some of the rescued residents had minor injuries, but no fatalities have been reported, Seuzeneau said.

“I pray it stays this way; we have no reports of major injuries or fatalities,” he said. “If we somehow can make it out without any fatalities, it’s a miracle.”

An EF-1 tornado struck a Houston suburb early Wednesday, according to the National Weather Service.

The full damage survey was still ongoing Wednesday afternoon, but damage in the town was consistent with an EF-1 tornado packing 90 mph maximum winds, according to the service.

Other information, including the tornado's complete path, will be finalized when survey teams finish assessing damage.

There were no injuries from the storm in Katy, which damaged a strip mall and neighboring car maintenance business.

The tornado struck the businesses while they were still closed, which Assistant Fire Chief Mark Donovan said was also a stroke of good luck.

“I think we’re very fortunate that this took place when it did,”said Donovan.

CNN meteorologist Mary Gilbert contributed to this report.

A video posted to X shows the torrential rainfall New Orleans is dealing with at the moment. The city is under a flash flood emergency until until 3 p.m. ET (2 p.m. CT).

"Emergency management reported many roads in and around New Orleans are currently under water and impassible," the National Weather Service in New Orleans said.

At least 3 inches of rain have fallen in a short period of time, with more expected.

A line of powerful and dangerous severe thunderstorms is crossing the Mississippi and Alabama border. The line of storms is showing a bowed shape on radar, a sign it will unleash strong winds in its path.

Wind gusts of 70 mph are possible with any storms in this line in southwest Alabama, according to National Weather Service warnings. Tornado warnings were issued for parts of this line of storms in Louisiana and Mississippi, so prepare for tornadoes in Alabama, too.

The storms will also bring hail and gushing rainfall that could cause flooding issues.

The police department in Slidell, Louisiana, is warning residents to stay indoors and find a safe place, after a possible tornado hit the area Wednesday morning and left extensive damage in the city.

Slidell is northeast of New Orleans.

According to the police department, several homes, businesses, apartment complexes, and power lines were damaged in south Slidell.

“We are slammed busy right now, and things are not safe. Road conditions are not safe. Stay home, stay off the roads,” he said.

Videos posted by the Slidell Police Department's Facebook page show downed power lines and damaged businesses.