Last Updated 5:03 p.m. ET
(CBS/AP) WASHINGTON - Airlines cancelled hundreds of flights as Tropical Storm Isaac lashed southeastern Florida Sunday.
The airports in Miami and Fort Lauderdale were hit the hardest, cancelling 573 flights the vast majority of the 654 U.S. flights grounded overall because of the storm as of Sunday morning, according to the flight-tracking service FlightAware.
American Airlines and its American Eagle affiliate cancelled 460 flights. The last American flight left Miami at noon Sunday. The airline hopes that inbound and outbound Miami flights can resume by 10 a.m. Eastern time Monday, said airline spokeswoman Andrea Huguely. But specific plans "will depend on the path Isaac takes," she said. American runs a hub in Miami, a jumping-off point for flights to the Caribbean and Latin America.
Isaac, already carrying winds of more than 60 miles an hour, was expected to cross the Keys by late afternoon. The storm will likely pick up strength from the warm, open waters of the Gulf of Mexico and strike as a dangerous Category 2 hurricane somewhere between New Orleans and the Florida Panhandle on Wednesday, the seventh anniversary of Hurricane Katrina.
Inside the American Airlines terminal in Miami Sunday, travelers craned for a look out of one of the doors as Isaac pelted the airport with strong rain and wind.
At Fort Lauderdale-Hollywood International Airport, the check-in line at the Southwest Airlines counter was completely empty at 7 a.m. Typically at that time on a Sunday the area is jammed, mainly by people leaving from vacations and cruises.
Delta Air Lines dropped three round-trip flights between its Atlanta hub and hard-hit Key West. "No others as of yet," Delta spokesman Morgan Durrant said by email Sunday afternoon. "We anticipate running a full schedule with the exception of Key West."
United Airlines and its United Express affiliate dropped 26 flights in the path of the storm.
Tampa, where the Republican party postponed the start of its political convention because of bad weather, has largely been spared flight cancellations: Just 26 inbound and outbound Tampa flights had been cancelled Sunday morning, according to FlightAware.
The airlines are waiving fees for travelers who have to change their plans because of Isaac.
Amtrak on Saturday suspended part of its Silver Service line between Miami and Orlando through Monday "as a precaution against potential damaging winds and flooding."