NEW ORLEANS (AP) — St. Charles Parish officials ordered evacuation Sunday for the parish’s 53,000 residents as Tropical Storm Isaac’s path moved west, threatening harsh winds and downpours from the sprawling storm.

The order was made Sunday evening because conditions are expected to worsen, parish spokeswoman Renee Simpson said. It was the largest evacuation so far in southeast Louisiana, where 15 coastal parishes east of Morgan City are under a hurricane warning.

“Early, early Tuesday ... is when we could see the greatest storm conditions in this area,” said Scott Whelchel, homeland security director for St. Charles Parish.

Isaac was expected to hit land as a strong Category 2 hurricane on Wednesday, the seventh anniversary of Hurricane Katrina, which flooded 80 percent of New Orleans and all of neighboring St. Bernard Parish in 2005, killing more than 1,400 Louisiana residents. The National Weather Service set a hurricane warning from east of Morgan City to Destin, Fla.

Jindal said the storm could bring 12 to 16 inches of rain with tropical storm winds — 39 to 74 mph — lasting up to 36 hours and up to eight hours of hurricane winds, defined as 75 mph or more, Gov. Bobby Jindal said. He called a state of emergency, suggesting people leave low-lying parts of the 15 parishes under a hurricane watch — Orleans, St. Bernard, Plaquemines, Jefferson, St. Charles, Lafourche, Terrebonne, Assumption, St. James, St. John, Ascension, Livingston, Tangipahoa, St. Tammany and Washington. State offices in all 15 will be closed Monday, officials said.

Earlier Sunday, Grand Isle Mayor David Camardelle ordered evacuation of the state’s only occupied barrier island, with tourists leaving Sunday and residents at 9 a.m. Monday. That also was when Lafitte Mayor Tim Kerner called a voluntary evacuation for the Lafitte, Crown Point, and Barataria in Jefferson Parish.

Evacuation was ordered Monday for occupants of Plaquemines Parish’s east bank — about 2,000 people — and voluntary evacuation for another 5,000 in the southern part of the parish. Most of the parish’s 23,000 residents live in Belle Chasse, where the parish was to open a shelter Monday.

If Isaac remains a threat to Louisiana, Jindal said, he will skip the Republican National Convention, where he is scheduled to speak Tuesday night. He said Isaac’s projected track seems to be moving west with each new forecast, heightening the threat to Louisiana.

That was why St. Charles Parish officials ordered the evacuation Sunday evening, with a 4:30 p.m. Monday deadline for anyone who needed parish assistance, Whelchel said.

“Only a few forecasts ago, the National Hurricane Center had this hurricane making landfall over 220 miles away in Florida. Now we find it right here, just this very small distance from our parish,” he said.

Whelchel said National Weather Service forecasters told him that a shift of 40 to 60 miles west would mean 5 ½ to 8 feet of storm surge in St. Charles Parish, which has no hurricane protection levee on its west bank. “Eighty percent of our structures on our west bank are at 5 feet of elevation or lower,” he said.

Public schools in several parishes, including Lafourche, Orleans and St. Charles, will be closed through Wednesday.

Jindal said Louisiana agencies were readying shelters, rescue boats, generators, buses for possible evacuations and items like tarps and sandbags. Prisoners in low-lying coastal areas were being moved to state prisons. Cleanup efforts from the BP oil spill were suspended.

Jindal said a state shelter was being readied Sunday in the central Louisiana city of Alexandria. “They’re putting up cots as we speak,” he said.

New Orleans Mayor Mitch Landrieu and heads of St. Bernard, Plaquemines, Jefferson and St. Charles all declared a state of emergency.

“Now is the time that we should get in battle rhythm,” Landrieu said.

Some Grand Isle residents weren’t waiting for their mayor’s evacuation deadline. At Ricky’s Motel, where one room and several RV parking spots were occupied before the announcement, manager Meakle Thibodaux said she was heading north as soon as the motel office closed Sunday afternoon. Most of the 15 rooms and three camps at the Cajun Holiday Motel were full until the evacuation order came Sunday, manager Millie Green said.

The Department of Transportation and Development suspended tolls on the highway at Leeville, the highway to Grand Isle, to ease evacuation and emergency services.

People who live outside hurricane protection levees, south of the Intracoastal Waterway and in other areas that they know are likely to flood in the 15 parishes under a hurricane watch should leave on their own, without waiting for officials to call for evacuation, Jindal said.

In Plaquemines Parish, crews were lining newly raised levees on the east bank of the Mississippi River with heavy plastic on Sunday to protect exposed dirt, and adding Hesco baskets to close gaps in low areas along Louisiana Highway 23, a news release said. Other crews were adding sandbags to levees in Pointe-a-la-Hache.

Parish and Army Corps of Engineers officials will discuss plans for barges that have been pumping fresh water into the parish system at Port Sulphur and Pointe-a-la-Hache because the low Mississippi River had let salt water move up from the Gulf of Mexico to freshwater intakes.

Mayor Mitch Landrieu said he expects New Orleans residents to shelter in place. But people need to be ready to leave, because if New Orleans is evacuated, there won’t be anywhere in the city to stay, he said.

“Neither the airport nor the Superdome nor the Convention Center is going to be a shelter of last resort,” he said. “In the event that an evacuation is called, everybody needs to make preparations because we will not be sheltering there.”

The New Orleans Fair Grounds Race Track ordered evacuation of about 700 horses from its stables and canceled races scheduled Wednesday through Sunday, saying they probably will rescheduled.

The New Orleans Saints canceled Monday practice and meetings to let players evacuate their families but planned to practice in Metairie on Tuesday before flying early to Tennessee to prepare for their final preseason game on Thursday against the Titans, interim coach Joe Vitt said. If they must leave earlier, he said, they will fly to Cincinnati on Monday if needed and practice in Nashville on Tuesday.