New Orleans on Tuesday braced for another hurricane as a strengthening Tropical Storm Isaac drew near, seven years after Hurricane Katrina left 1,800 dead in the fabled jazz city.
The US National Hurricane Center said in its 0900 GMT advisory that Isaac was "on the verge" of becoming a hurricane, warning of a "significant storm surge and freshwater flood threat to the northern Gulf coast."
The Miami-based NHC predicted the center of the storm would be over the Louisiana coast by late Tuesday or early Wednesday, saying "preparations to protect life and property should be rushed to completion."
President Barack Obama, no doubt mindful of the bungled handling of Katrina by his predecessor George W. Bush, on Monday declared a state of emergency in Louisiana, allowing federal funds and aid to flow to local authorities.
The president also convened a briefing with officials, including Federal Emergency Management Agency (FEMA) administrator Craig Fugate, hours before Tropical Storm Isaac was expected to become a Category One hurricane.
Katrina left behind a devastating sprawl of destruction and death when it hit New Orleans on August 29, 2005, and a halting emergency response from the Bush administration was a black mark on his second term in office.
A hurricane warning was issued earlier for New Orleans and nearby areas as Isaac churned toward the US Gulf coast, and Alabama governor Robert Bentley ordered mandatory evacuations in two Gulf coast counties.
In New Orleans, the normally bustling French Quarter was eerily quiet late Monday as the first rain drops fell and winds picked up.
Bored bouncers peered out of empty bars and strip clubs along Bourbon Street as the few die-hard tourists staggered down the cobblestones. Many restaurants had closed, and some hotels told guests to check out by midday Tuesday.
Louisiana Governor Bobby Jindal, who has recommended voluntary evacuations, urged people to prepare for the worst.
"If you are in low-lying areas and are thinking about evacuating, today is the day to do that," he said Monday.
"If you plan on hunkering down at home, today is the day to get supplies. I strongly encourage people not to wait," added Jindal, who stayed away from the weather-delayed Republican National Convention in Tampa, Florida.
Those heeding the call included Tammy Edmondson, who looked anxious as she picked through the grocery shelves at a Target store with her daughter.
Edmondson said she left town ahead of Katrina and that it was a month before she could go home. "We had a lot of damage -- we're still fixing some of it," she said.
FEMA said its National Response Coordination Center had been activated and would handle eventual requests for aid from affected states.
The emergency management agency has also deployed four disaster response teams to Gulf states and has moved other resources to pre-positioned command locations closer to the potential storm impact areas.
Mississippi activated 1,500 National Guard troops on Monday and Louisiana issued orders to approximately 4,100 soldiers and airmen in preparation of the storm making landfall. Florida called up only a few dozen service personnel.
Louisiana, Mississippi and Alabama issued emergency warnings on Sunday, 24 hours after Isaac forced the main program of the Republican convention to be postponed by one day.
The NHC warned that Isaac could dump up to 18 inches (45 centimeters) of rain along the Gulf coast and spawn "isolated tornadoes" over central and northwestern Florida.
Katrina was the third deadliest US hurricane on record, destroying homes and igniting a human crisis in New Orleans, a city famed for music, an easygoing atmosphere and Creole cuisine.
Seven years ago, 1.4 million residents and visitors were ordered to evacuate New Orleans as Hurricane Katrina approached, but many could not or would not leave and ended up stranded.
A lack of preparation forced residents to take shelter in attics and then break through their roofs to escape rising water, but countless numbers died while the nation's leaders appeared unwilling to address the disaster.
Isaac brought rain and choppy seas to the US coast after battering impoverished Haiti -- where 19 people died -- and Cuba over the weekend.
In Tampa, the Republican convention began with a whimper as the bad weather reduced the opening of Mitt Romney's coronation as the party's presidential candidate to a muted, symbolic session of less than two minutes.
Party officials have said prime-time speaking slots on Tuesday, Wednesday and Thursday -- including speeches by Romney, his wife Ann and running-mate Paul Ryan -- remain unchanged.