The potential for a landfall as soon as Tuesday prompted evacuations along a wide area of the Gulf Coast and sent people out to stock up on staples.
"I gassed up — truck and generator", John Corll, 59, a carpenter, said as he left a New Orleans coffee shop Monday morning. He went through Katrina in 2005 and was expecting a weaker storm this time, adding that he thinks the levee system is in better shape to handle a storm surge than when Katrina hit. "I think the state and local governments are much better prepared for the storm surge and emergencies," Corll said.
Isaac blew past the Florida Keys and was rolling northwestward over the open Gulf of Mexico on Monday. The National Hurricane Center predicted it would grow to a Category 1 hurricane over the warm water and possibly hit late Tuesday somewhere along a roughly 300-mile stretch from the bayous southwest of New Orleans to the Florida Panhandle.
That would be one day shy of seven years after Katrina struck catastrophically in 2005, although Katrina was a much stronger Category 5 storm with winds over 157 miles per hour. Isaac is expected to have top winds of around 90 mph when it hits land.
The size of the warning area and the storm's wide bands of rain and wind prompted emergency declarations in four states, and hurricane-tested residents were boarding up homes, sticking up on food and water or getting ready to evacuate.
On the Alabama coast, Billy Cannon, 72, was preparing to evacuate with several cars packed with family and four Chihuahuas from a home on a peninsula in Gulf Shores. Canon, who has lived on the coast for 30 years, said he thinks the order to evacuate Monday was premature.
"If it comes in, it's just going to be a big rain storm. I think they overreacted but I understand where they're coming from. It's safety," he said.
The storm that left eight dead in Haiti blew past the Florida Keys with little damage and promised a drenching but little more for Tampa, where the planned Monday start of the Republican National Convention was pushed back a day in case Isaac passed closer to the bayside city.
Isaac could pack a watery double punch for the Gulf Coast. If it hits during high tide, Isaac could push floodwaters as deep as 12 feet onto shore in Louisiana, Mississippi and Alabama and up to six feet in the Florida Panhandle, while dumping up to 18 inches of rain over the region, the National Weather Service warned.
Louisiana Gov. Bobby Jindal called a state of emergency, and 53,000 residents of St. Charles Parish near New Orleans were told to leave ahead of the storm. Mississippi Gov. Phil Bryant, Florida Gov. Rick Scott and Alabama Gov. Robert Bentley also declared states of emergency.
The oncoming storm stopped work on rigs that account for 24 percent of daily oil production in the U.S. potion of the Gulf of Mexico and eight percent of daily natural gas production there, the federal Bureau of Safety and Environmental Enforcement said in its latest update Sunday.
The Gulf of Mexico accounts for 23 percent of total U.S. crude oil production, 7 percent of the nation's natural gas and more than 40 percent of refining capacity.
Several regional governors altered their plans for this week's GOP convention in Tampa. Bentley has canceled his trip, and Jindal said he's likely to do so unless the threat from the storm subsides. Scott gave up a chance to speak.
Amtrak cancelled train service in Louisiana for Tuesday and Wednesday. The route than runs from New York to New Orleans would end in Atlanta, while its route from Los Angeles to New Orleans would stop in San Antonio. Amtrak was also suspending part of its rail line between Miami and Orlando, Fla.
Grocery and home improvement stores as well as fuel stations in Louisiana reported brisk business as residents sought to prepare for Isaac. Some gas stations were running out of supplies.
Even though the storm was moving well west of Tampa, tropical storm-force winds and heavy rains were possible in the area because of Isaac's large size, forecasters said. A small group of protesters braved rainy weather Sunday and vowed to continue despite the weather, which already forced the Republicans to cancel Monday's opening session of the convention. Instead, the GOP will briefly gavel the gathering to order Monday afternoon and then recess until Tuesday.
The Gulf Coast hasn't been hit by a hurricane since 2008, when Dolly, Ike and Gustav all struck the region.