Tropical Storm Isaac rolled over the open Gulf of Mexico on Monday, where it was expected to grow into a hurricane before hitting land somewhere between Louisiana and Florida and close to the seventh anniversary of Hurricane Katrina.
The storm that left 21 dead in Haiti and the Dominican Republic 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.
The National Hurricane Center predicted Isaac would grow to a Category 1 hurricane over the warm Gulf and possibly hit late Tuesday somewhere along a roughly 300-mile (500-kilometer) stretch from the bayous southwest of New Orleans to the Florida Panhandle. That would be one day shy of seven years after Hurricane Katrina struck catastrophically in 2005.
Earlier predictions said Isaac would be a Category 2 hurricane but National Hurricane Center director Rick Knabb told ABC's "Good Morning America" on Monday that Isaac wouldn't be as strong as they initially thought. But Knabb urged residents not to focus their preparations the storm's current strength because such storms often do not stick to forecasters' predictions.
The size of the warning area and the storm's wide bands of rain and wind prompted emergency declarations in four states, and the hurricane-tested residents were boarding up homes, sticking up on food and water or getting ready to evacuate.
Forecasters said Isaac could pack a double punch of flood threats for the Gulf Coast. If it hits during high tide, the storm could push floodwaters as deep as 12 feet (four meters) on shore in Louisiana, Mississippi and Alabama and up to six feet in the Florida Panhandle.
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.
Meanwhile, the oncoming storm stopped work on rigs that account for 24 percent of daily oil production in the U.S. portion 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.
Several area governors have altered their plans for this week's Republican 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.
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 Republicans will briefly gavel the gathering to order Monday afternoon and then recess until Tuesday.
As of 1200 GMT Monday, the storm was centered about 185 miles (295 kilometers) west-southwest of Fort Meyers, Florida., and 360 miles (575 kilometers) southeast of the mouth of the Mississippi River, according to the National Hurricane Center in Miami. Isaac had top sustained winds of 65 mph (100 kph) and was moving west-northwest near 14 mph (22 kph).
Florida, historically the state most prone to hurricanes, has been hurricane-free since it was hit four times each in 2004 and 2005.
Isaac knocked out power temporarily for around 16,000 customers throughout South Florida, and 555 flights were canceled at Miami International Airport. That forced some people to shuffle their travel plans and kept many, at least for a day, from enjoying their beach vacations.
In the low-lying Keys, isolated patches of flooding were reported and some roads were littered with downed palm fronds and small branches. But officials said damage appeared to be minimal, and many Keys residents held true to their any-excuse-for-a-party reputation.
The Gulf Coast hasn't been hit by a hurricane since 2008, when Dolly, Ike and Gustav all struck the region.
Before reaching Florida, Isaac was blamed for 19 deaths in Haiti and two more in the Dominican Republic, and downed trees and power lines in Cuba. It bore down on the Keys two days after the 20th anniversary of Hurricane Andrew, which caused more than $25 billion in damage and killed 26 people in South Florida.
Associated Press writers Tony Winton in Key West, Melissa Nelson in Pensacola, Florida.; Mike Schneider in Tampa, Florida.; and Tim Reynolds, Curt Anderson and Suzette Laboy in Miami contributed to this report.