(CNN) - Barry weakened Sunday afternoon as it crept over northwestern Louisiana, but the storm was still threatening millions with possible "life-threatening" flooding.
As it headed deeper inland, Barry was downgraded to a tropical depression, according to the National Hurricane Center's latest public advisory.
A tropical storm is a weather system that has sustained winds from 39 mph to 73 mph. The sustained wind speeds of a tropical depression are up to 39 mph.
As of Sunday afternoon, Barry was crawling north across Louisiana at around 9 mph -- slower than a bicyclist. That means it's still hovering over the same state where it made landfall Saturday, dumping copious amounts of rain on cities already deluged.
And it's not even close to done.
"Barry is expected to produce additional rain accumulations of 3 to 6 inches across portions of the lower Mississippi Valley with isolated maximum amounts of 10 inches across eastern Arkansas, western Tennessee, southeast Missouri, and northwest Mississippi," the NHC said.
An additional 3 to 5 inches of rain are expected across south-central Louisiana, with as much as 15 inches in some spots, the NHC said, adding that the additional rain could cause "dangerous, life-threatening flooding."
More than 11 million people are under flash-flood watches Sunday from the Gulf Coast all the way to the southern Midwest, CNN meteorologist Haley Brink said.
"Tornadoes are also possible across areas of Louisiana, Mississippi, Alabama, and Arkansas today," she said.
"The system is expected to track -- slowly -- north over the coming days, bringing heavy rain with it along the Mississippi River."
The center of the tropical depression is forecast to move into Arkansas Sunday evening and Monday, the NHC said.
Louisiana's governor urged residents to stay alert and follow any orders from officials.
"Now is not the time to let your guard down," Edwards said. "In addition to the rainfall, there has been increased tornadic activity and a continued chance for more flash flooding as well."
'The house was under water'
In St. Mary Parish, about 60 miles east of where Barry made landfall, 64-year-old Joyce Webber hunkered down with about 20 other people at a community center when she learned a large tree branch had fallen on her mobile home, and her storm door had blown off.
"Trailers don't hold, no matter what type of storm," Webber said. "They just don't hold."
In Mandeville, Ludovico Torri woke up Saturday to a surprising sight: Lake Pontchartrain was suddenly at the door of his house.
"The entire street and area under the house was underwater," Torri said.
It took just 90 minutes for the water to rise another foot. Torri's car nearly flooded. And his family, including four children, were stranded in their home.
Others, like Ollie and Hazel Jordan, struggled to find a place where both they and their pets can stay safe. The couple, both in their early 70s, walked a mile in the rain from their trailer to a shelter at a Baton Rouge middle school -- only to be told they couldn't in their two cats and small dog.
But officials learned after Hurricane Katrina that some residents wouldn't evacuate because they couldn't bring their pets. That led to tragic outcomes.
This time, officials set up a mobile disaster pet shelter, where the Jordans were able to safely house their dog and cats.
Torrents of water overwhelm levees
Three levees in St. Mary Parish were overtopped by water Saturday, said David Naquin, the parish's director of homeland security and emergency preparedness.
The Glencoe community had to be evacuated, but Naquin said Sunday he believes only a few homes have flooded.
In Plaquemines Parish, southeast of New Orleans, multiple levees were overcome by floodwaters Saturday.
The overtopping happened in less populated areas. But officials worry that Highway 23 could flood, trapping more residents.
The Big Easy can breathe a bit easier
The good news: Fears of catastrophic storm surges overwhelming New Orleans' levee system didn't materialize this weekend. But that doesn't mean Barry is done thrashing the Big Easy.
All eyes were on the Mississippi River, as forecasts showed a possible storm surge of 2 to 3 feet that could have raised the river's level to 19 feet in New Orleans. The levees protect up to only 20 feet.
But the storm surge was lower than expected. And even with the heavy rain ahead, the National Weather Service is now only predicting the river will rise only to 17.1 feet, with the next crest expected to happen on Monday.