Haitian authorities identified 1,250 shelters throughout the country, 500 of them in the capital. The International Organization for Migration opened about 45 early, spokesman Leonard Doyle said. But the storm will still take a heavy toll. “It’s all very, very bad news for Haiti.’’

In South Florida, the Keys and Southwest Florida were expected to feel the brunt, with tropical force winds beginning early Sunday and building to hurricane force throughout the day. Much of South Florida, including Miami-Dade and Broward, could see tropical storm-force winds.

“It’s going to be a day to stay inside,” said Adam Futterman, a meteorologist in the National Weather Service’s Key West office. “Travel is strongly discouraged.’’ Once in warm waters in the Gulf of Mexico, Isaac also could whip into a far more formidable concern next week as it bears down on the Panhandle. The NHC had it approaching the region Tuesday as a Category 1 hurricane.

Gov. Rick Scott said that he was increasingly concerned about North Florida.

“The more time it spends over warm water, the greater chance it will be a worse storm,” he said late Friday. “No evacuations in the state at this point.”

Scott plans to hold two storm briefings in Broward County on Saturday before he heads to Tampa on Sunday with his wife, children and mother for the Republican National Convention. Scott was still hopeful that the convention would not be disrupted. “We’re still a couple of days out and we’ll see what happens,” he said. “My biggest concern is the safety of the citizens.”

Though they weren’t facing a major hurricane, many South Florida residents were taking no chances, reminded of the possibilities by the 20th anniversary of Hurricane Andrew, a Category 5 monster that devastated South Miami-Dade. Supermarkets and hardware stores reported steady traffic. “We’ve been seeing a rush in our stores for your typical supplies,” said Winn-Dixie spokeswoman Mayra Hernandez. “With the anniversary of Andrew people are just alarmed, and it’s best to be prepared.”

But at Casey’s Corner Nursery in Homestead — ground zero for Andrew — it was business as usual. On Friday, owner Susan Casey was pulling plants for a show.

“Honey, there’s no wind out here. There’s no rain out here,” she said. “I go by what I see outside and my feelings, and there’s nothing.”

Miami Herald staff writers Jacqueline Charles in Haiti; Cammy Clark in the Keys; Christina Veiga, Ina Paiva Cordle, Frances Robles and Charles Rabin in Miami; and Toluse Olorunnipa and Times/Herald staff writer Brittany Alana Davis in Tallahassee contributed to this report.