Hurricane Barry is barreling northwest toward Louisiana, packing maximum sustained winds of 75 miles per hour (120 km/h), with heavy rain, storm surges and unsafe winds expected along the northwest Gulf Coast.
Hurricane Katrina, which hit New Orleans in 2005, caused catastrophic flooding and was blamed for as many as 1,800 deaths in Louisiana and other states.
Despite the flooding concern, however, New Orleans experienced only light rain and winds on Saturday, and no flooding.
Though the system was downgraded to a tropical depression Sunday afternoon and its winds were steadily weakening since it made landfall Saturday in Louisiana, Barry's rain bands created a flooding and tornado threat stretching from central Louisiana to eastern MS and beyond.
Governor Gavin Newsom is sending emergency teams from California to Gulf States to assist in relief efforts against Tropical Storm Barry.
"This rainfall is expected to lead to risky, life-threatening flooding", forecasters wrote in an advisory Sunday morning.
Officials said an estimated 400 people were ordered evacuated in Terrebonne Parish, which is about 100 kilometers (62 miles) southwest of New Orleans.
That tropical moisture from Barry will add to the building humidity this week in Upstate New York.
Barry's centre was moving from northern Louisiana into Arkansas.
The Governer took to twitter to say that "No one should take this storm lightly".
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About 75,000 customers in Louisiana, 4,000 customers in MS and another 1,800 customers in Arkansas were without power Sunday evening, according to poweroutage.us.
Fears that the levee system in New Orleans could be compromised had eased after the Army Corps of Engineers voiced confidence that it would hold, but Mayor LaToya Cantrell urged residents not to be complacent.
But it said "life-threatening storm surge inundation" continued as it moved inland.
By 12pm Central on Sunday, more than 126,000 buildings in Louisiana and MS were without power, according to PowerOutage.US.
This graphic from the National Weather Service shows observed rainfall.
Around 300 National Guard troops and rescue teams have been stationed around Louisiana with boats, high-water vehicles and helicopters. Mandatory evacuations were being put into effect for areas south of Highway 317 with sheriff's deputies going door to door to notify residents.
In Mandeville, a city on the north shore of Lake Pontchartrain across from New Orleans, storm surge and choppy waters sent waves over the seawall and into nearby communities.
The National Hurricane Centre at the NOAA warned: "Life-threatening flash flooding and significant river flooding are still expected along Barry's path inland from Louisiana up through the lower Mississippi Valley, through at least Monday".
The rain was expected to raise the already flooded Mississippi River but not overtop the levees. The couple, 72 and 70-years-old respectively, walked a mile in the rain from their trailer to a shelter at a Baton Rouge middle school only to be told that they could not bring in their two cats and small dog.