NEW ORLEANS (CNN) -- New Orleans and much of the Gulf Coast faced the anniversary of devastating Hurricane Katrina by hunkering down for a new storm amid "a high level of anxiety," as the Crescent City's mayor put it Monday.
Forecasters project Tropical Storm Isaac will reach hurricane strength and could be a Category 2 storm when it hits the northern Gulf Coast early Wednesday, seven years to the day after Katrina slammed ashore near the Louisiana-Mississippi state line. Residents of low-lying coastal areas from the Florida Panhandle to southeastern Louisiana were ordered to evacuate ahead of storm surges and heavy rain, while New Orleans Mayor Mitch Landrieu acknowledged his own jitters due to the coincidence.
Isaac is expected to be weaker than Katrina, a Category 3 hurricane with 125-mph winds. But as of Monday afternoon, the National Hurricane Center projected Isaac would come ashore with top winds around 100 mph.
New Orleans could start to feel tropical storm force winds by midnight Monday, and while Isaac may veer off its currently projected course, "It seems to be settling into a pathway and a speed that is becoming predictable," Landrieu said.
"It is quite ironic that we have a hurricane threatening us on the seventh anniversary of Katrina," he said. "That brings a high level of anxiety to the people of New Orleans." But he added that as of Monday afternoon, "There is nothing this storm will bring us that we are not capable of handling."
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.
At 5 p.m. ET Monday, Isaac was centered about 255 miles (415 kilometers) southeast of the mouth of the Mississippi River. Its top winds had increased to 70 mph (110 km/h), just 4 mph below hurricane strength, and it was moving to the northwest at 12 mph, the Miami-based National Hurricane Center reported.
The projected track brings it ashore before dawn Wednesday in the marshes downriver from New Orleans. But tropical-storm-force winds extended more than 200 miles from the center, and hurricane warnings stretched from Morgan City, Louisiana, to the Alabama-Florida border; while tropical storm warnings extended eastward to Destin, Florida and westward from Morgan City to Intracoastal City, Louisiana, about 150 miles west of New Orleans.
Landrieu has not ordered an evacuation of his city, most of which is below sea level and protected by a network of levees. But he said he would "strongly urge" about 900 people who live outside the levee system to leave -- and if anyone else is thinking about getting out, "now would be a good time to go."
Others in low-lying Louisiana parishes and in 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 Hurricane Center projected storm surges of three to six feet for the Florida Panhandle, six to nine feet for the Alabama coast and six 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, said Alexa Alexander.
"We are boarding up getting supplies ready," said 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. The skies there were just clouding up Monday afternoon, Alexander told CNN.
And Louisiana resident Ryan Unger plans to stay in place despite an evacuation order. He filled up gas tanks Sunday night in case he has to run his generator.
"Starting to get a little sense of anxiety, like, OK, am I ready for it?" he said. "Realizing we ain't really ready for a storm. So we're just all thinking about what we gotta do to get in place to get ready for it."
Some 9,000 residents in Jefferson Parish, Louisiana, were ordered to evacuate Monday morning. The towns of Jean Lafitte, Crown Point and Barataria are affected.
"We're worried about tidal surge," Jean Lafitte Mayor Tim Kerner said.
And Louisiana Gov. Bobby Jindal called on residents in coastal parishes prone to flooding to voluntarily evacuate. A mandatory evacuation was ordered for St. Charles Parish and for parts of Plaquemines Parish.
Even pro football player Courtney Roby of the New Orleans Saints was a little nervous.
"Kinda a scary feeling of uncertainty," he said via Twitter.
Mississippi officials dispatched 1,500 National Guard troops to the state's three southern counties to help with emergency operations, as well as 45 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.
In the coastal Mississippi city of Pass Christian, people were moving their boats to higher ground and preparing their homes.
"Lookin' like we're gonna be ground zero again," said Daryl Vaught, as he prepared to place sandbags in front of his doors and garage.
"It seems like Katrina just happened yesterday," Vaught told CNN affiliate WDSU. "Hopefully we'll dodge a bullet here this time. I didn't last time."
It appeared Monday that the storm's ferocity would mostly bypass Florida's west coast and the Republican National Convention in Tampa, where the schedule was pushed back a day by organizers over concerns about the storm. Isaac's eye is forecast to pass well west of Tampa.
Still, Isaac's reach is so large that much of south Florida got heavy doses of rain and wind. In Pompano Beach, Florida, Scott Segal put up hurricane shutters outside his condo as the rain came in horizontally.
"The wind is getting stronger, and the ocean is starting to build, and the waves are getting bigger," he said. "I am prepared, but not nervous."
After slamming into Haiti, where at least six people died in storm-related incidents Saturday, Isaac lashed Cuba and the Florida Keys.
As preparations continued on the northern Gulf Coast, Florida Gov. Rick Scott was assessing damage as Isaac skirted the state's western coast, bringing strong winds and heavy rain.
"We are experiencing some minor outages in the southern part of the state," he said at a news conference in Tampa. He said his main concern for Tampa was no longer a direct hit from Isaac but tropical-storm-force winds.