NEW ORLEANS — Hurricane Isaac spun into the southern Louisiana coast late Tuesday, sending floodwaters surging and unleashing fierce winds as residents hunkered down behind boarded-up windows. New Orleans calmly waited out another storm on the eve of Hurricane Katrina’s seventh anniversary, hoping the city’s strengthened levees will hold.

Isaac, a massive storm spanning nearly 200 miles from its center, made landfall at about 6:45 p.m. near the mouth of the Mississippi River. But it was zeroing in on New Orleans, about 75 miles to the northwest, turning streets famous for all-hours celebrations into ghost boulevards.

The storm drew intense scrutiny because of its timing — just before the anniversary of the hurricane that devastated that city, while the first major speeches of the Republican National Convention went on in Tampa, Fla., already delayed and tempered by the storm

While many residents stayed put, evacuations were ordered in low-lying areas of Louisiana and Mississippi, where officials closed 12 shorefront casinos. By late Tuesday, more than 100,000 homes and businesses had lost power.

Ed Rappaport, deputy director of the National Hurricane Center, said Isaac’s core would pass west of New Orleans with winds close to 80 mph and head for Baton Rouge.

“On this course, the hurricane will gradually weaken,” Rappaport said Tuesday night from the Miami-based center. He said gusts could reach about 100 mph at times, especially at higher levels which could damage high-rise buildings in New Orleans.

As Isaac neared the city, there was little fear or panic. With New Orleans’ airport closed, tourists retreated to hotels and most denizens of a coastline that has witnessed countless hurricanes decided to ride out the storm.

“Isaac is the son of Abraham,” said Margaret Thomas, who was trapped for a week in her home in New Orleans’ Broadmoor neighborhood by Katrina’s floodwaters, yet chose to stay put this time. “It’s a special name that means ‘God will protect us’.”

Officials, chastened by memories and experience, advised caution.

“We don’t expect a Katrina-like event, but remember there are things about a Category 1 storm that can kill you,” New Orleans Mayor Mitch Landrieu said, urging people to use common sense and to stay off any streets that may flood.

Tens of thousands of people were told to leave low-lying areas, including 700 patients of Louisiana nursing homes, but officials decided not to call for mass evacuations like those that preceded Katrina, which packed 135 mph winds in 2005.

Isaac also promised to test a New Orleans levee system bolstered after the catastrophic failures during Hurricane Katrina. But in a city that has already weathered Hurricane Gustav in 2008, calm prevailed.

“I feel safe,” said Pamela Young, who settled in to her home in the Lower 9th Ward — a neighborhood devastated by Katrina — with dog Princess and her television. “Everybody’s talking ‘going, going,’ but the thing is, when you go, there’s no telling what will happen. The storm isn’t going to just hit here.”

Young, who lives in a new, two-story home built to replace the one destroyed by Katrina, said she wasn’t worried about the levees.

“If the wind isn’t too rough, I can stay right here,” she said, tapping on her wooden living room coffee table. “If the water comes up, I can go upstairs.”

While far less powerful than Katrina, Isaac posed similar political challenges, a reminder of how the storm seven years ago became a symbol of government ignorance and ineptitude.

Political fallout was already simmering. Republican Gov. Bobby Jindal, who canceled his trip to the convention, said the Obama administration’s disaster declaration fell short of the federal help he had requested, and asked for a promise to be reimbursed for storm preparation costs.

“We learned from past experiences, you can’t just wait. You’ve got to push the federal bureaucracy,” Jindal said.

FEMA Administrator Craig Fugate said such requests would be addressed after the storm.

Obama promised that Americans will help each other recover, “no matter what this storm brings.”

“When disaster strikes, we’re not Democrats or Republicans first, we are Americans first,” Obama said at a campaign rally at Iowa State University. “We’re one family. We help our neighbors in need.”

The storm’s landfall didn’t appear to affect prime-time coverage of the RNC, where Ann Romney and New Jersey Gov. Chris Christie were to speak after a day of delays.

While politicians from both parties were careful to show their concern for those in the storm’s path, Gulf residents and visitors tried to make the best of the situation on the ground.

In New Orleans’ French Quarter, Hyatt hotel employee Nazareth Joseph braced for a busy week and fat overtime paychecks. Joseph said he was trapped in the city for several days after Katrina and helped neighbors escape the floodwaters.

“We made it through Katrina; we can definitely make it through this. It’s going to take a lot more to run me. I know how to survive,” he said.

Maureen McDonald of Long Beach, Ind., strolled the French Quarter on her 80th birthday wearing a poncho,  accompanied by family who traveled from three different cities to meet her in New Orleans to celebrate.

“The storm hasn’t slowed us down. We’re having the best time,” she said.

But farther east along the Gulf, veterans of past hurricanes made sure to take precautions.

At a highway rest stop along Alabama’s I-10, Bonnie Schertler, 54, of Waveland, Miss., said she left her coastal home for her father’s place in Alabama “because of the ‘coulds.”’

“I just feel like the storm may stay for a few days and that wind might just pound and pound and pound and pound,” said Schertler, whose former home in Waveland was destroyed by Hurricane Katrina. A slow storm is more dangerous, she said, “’cause it can knock down just virtually everything if it just hovers forever.”

Local officials, who imposed curfews in Mississippi’s Harrison, Hancock and Jackson counties. And in Theodore, Ala., 148 people took refuge in a shelter at the town’s high school by midday Tuesday, with minds focused as much on the past as on the present storm.

Charlotte McCrary, 41, at the shelter with husband, Bryan, and their two sons, 3-year-old Tristan and 1-year-old Gabriel, recalled the year she spent living in a FEMA trailer after Katrina destroyed her home.

Seven years later, the storm reminds her that she still hasn’t gotten back to same place.

“I think what it is,” Bryan McCrary said, “is it brings back a lot of bad memories.”