Tropical Storm Isaac closing in on Gulf Coast, hurricane status likely soon
"I don't know if it's going to be a true test, because they're saying it's not going to be that bad. But you never know what bad is. We didn't think Katrina was going to be bad, either."
Most of Katrina's nearly 1,800 deaths occurred when the protective levees around New Orleans failed, flooding the city. But Landrieu said the levees have had $10 billion in improvements since 2005, and the city's pump stations have backup generators ready in case of electrical outages.
One of those stations is the biggest in the world, and some can move as much as 150,000 gallons per second.
"This is the best system that the greater New Orleans area has ever seen," said Col. Ed Fleming of the Army Corps of Engineers.
A hurricane warning was in effect east of Morgan City, Louisiana, to the Alabama-Florida border, including metropolitan New Orleans. A hurricane watch was in effect from Intracoastal City to Morgan City, Louisiana.
Tropical storm warnings and watches extended to the east and west.
As the storm heads north, its rain is expected to benefit some drought-ravaged states like Arkansas, Illinois, Indiana and Missouri.
Some people in low-lying Louisiana parishes and coastal counties and barrier islands of Mississippi, Alabama and northwest Florida were told to clear out ahead of the storm. In Alabama, state Emergency Management Agency Director Art Faulkner warned that strong winds and high water may affect the Mobile area even if the storm hits as far west as Louisiana.
"It is a very large storm," Faulkner said. "And oftentimes we confuse and focus on a specific dot that may be identified as the center of the storm when very dangerous conditions may exist as far as 200 miles from that specific dot."
The storm lashed Cuba and the Florida Keys over the weekend after slamming into Haiti, where at least 19 people had been reported dead by Monday, the country's civil protection agency reported.
The Hurricane Center projected storm surges of 3 to 6 feet for the Florida Panhandle, 6 to 9 feet for the Alabama coast and 6 to 12 feet for the Mississippi and southeastern Louisiana shores.
But on Dauphin Island, south of Mobile, many residents were preparing to sit out Isaac at home as well.
"We are boarding up (and) getting supplies ready," said Alexa Alexander, who lives and tends bar on the island. "We've had a little bit of people leave Dauphin Island, but not much. Most of the locals are going to ride it out."
Dauphin Island was badly damaged by Katrina, which cut the island in half -- a gouge since filled by sand and rock.
In nearby Bayou La Batre, Alabama, shrimpers hunkered down.
"All the boats are coming in. We're anchoring them down and getting ready for this blow, hoping it's not too bad," Dominick Ficarino, the owner of Dominick's Seafood, told affiliate WPMI-TV.
Airports across the region also made plans to shut down as the storm passed. New Orleans shut its international airport after its last flight Monday night, spokesman Ryan Berni said, while smaller airports in Mississippi, Alabama and Florida also announced closures starting Tuesday.
Mississippi officials dispatched 1,500 National Guard troops to the state's three southern counties to help with emergency operations, as well as extra state troopers to ease traffic flow.
The state has distributed 10,000 sandbags to residents ahead of the storm.
"In short, we have done everything in our power to be prepared for the storm," Mississippi Gov. Phil Bryant said.
Most of the storm's ferocity bypassed Florida's west coast and the Republican National Convention in Tampa, where the schedule will begin in earnest Wednesday after organizers pushed events back a day because of concerns about the storm. The system passed well west of Tampa, although it did soak the bay area with heavy rain and blustery winds.
CNN's Ed Payne, Mariano Castillo, Matt Smith, Josh Levs, Dave Alsup, Chelsea J. Carter, Tom Cohen, Martin Savidge, Gary Tuchman and Jim Spellman, along with journalist Jean Junior Osman, contributed to this report.