A tropical storm warning for Isaac has been extended farther up Florida's west coast, north of the Tampa Bay area.
The wider warning comes soon before the Republican National Convention was scheduled to begin Monday. Most of the schedule has now been put off until Tuesday.
At 11 p.m. Saturday, the center of the storm was located about 340 miles (547 kilometers) east-southeast of Key West.
It was moving northwest at 17 miles per hour (27 kph) with maximum sustained winds of 60 mph (97 kph).
A tropical storm warning for Haiti, where Isaac killed at least four people, was canceled.
Tropical Storm Isaac is expected to scrape the coast of southwest Florida as it turns north into the Gulf of Mexico, said Storm Team 8 meteorologist Megan Hatton. It is now forecast to strengthen into a Category 2 hurricane before making landfall in northern Florida, Alabama or Mississippi, Hatton said.
The center of Issac is forecast to pass 60 to 120 miles west of Tampa on late Sunday night and during the day on Monday, said fellow Storm Team 8 meteorologist Brooks Garner.
The Tampa Bay area will see the heaviest wind and rain from the storm Sunday night into Monday, just as the Republican National Convention is expected to get under way, Hatton said.
But even as the storm moves past the area, heavy wind could continue to lash the Bay area, she said.
"Unfortunately because it’s a large storm, we’re going to be dealing with some wind for quite some time," Hatton said.
Gov. Rick Scott declared a state of emergency to make sure local and state agencies would be ready. The governor said during a media briefing that delegates were being told on how to stay safe during a storm, and officials were ready for storm surge, bridge closures and other problems that could arise during the convention. He also said he was in close communication with local, state and federal agencies, as well as convention officials.
"We are a hospitality state. We know how to take care of people and we want to ensure their safety," Scott said Saturday.
Garner said the storm could have winds of 85-100 mph within 50 miles of its eye when it passes us, but that should stay offshore. If the track deviates eastward, however, we could see that high wind closer to our shores.
Garner said it will be very breezy Sunday, becoming windy Sunday night and through the day Monday and then subsiding Tuesday.
Based on its forecast strength, winds will start blowing from the southwest – right up the Bay – Monday night into Tuesday. This could result in storm surge of 5 to 7 feet, according to the Weather Channel. Tropical Storm Debby was estimated to have produced a 2- to 4-foot surge.
This could flood Bay Shore and other prone coastal area, Garner said.
Roughly 70,000 people, including delegates, media members, protesters and visitors, are expected to be in town for the convention.
GOP officials said on Friday that the convention will go on.
There are no plans to shorten or cancel the event, which starts on Monday.
Protests were to start in full force on Sunday afternoon, and demonstrators have vowed that they will make their presence known rain or shine.
Convention CEO William Harris said GOP officials continue to plan for the event and expect a successful convention.
In the Florida Keys, officials organized shelters and urged vacationers to leave as Isaac approached on Saturday.
A hurricane warning had been issued for the Keys.
Isaac was blamed for at least three deaths after dousing flood-prone Haiti and was expected to scrape eastern Cuba on Saturday. It was forecast to hit the Keys late Sunday or early Monday, and it then could bring stormy conditions to Florida's west coast before moving to the Panhandle.
Still, the storm was days away from the Panhandle. It was sunny and breezy on the beach Saturday in Pensacola, with people out strolling and playing in the sand. Condo associations told people to move furniture inside, but full-scale preparations hadn't yet begun. Waves weren't yet big enough for surfers.
When the storm hits, strong winds will be "enough to knock you over" and produce severe thunderstorms, said National Hurricane Center spokesman Dennis Feltgen.
Storm surge and tornadoes also are possible when Isaac hits, and winds could topple power lines and lead to lengthy power outages, Feltgen said. The Panhandle already has had a wet summer, so potential flooding was especially possible there.
Schools, airports, parks and beaches across South Florida closed ahead of the storm. In the Florida Keys, officials said they would open storm shelters and urged vacationers to leave. State officials warned Isaac was a massive storm — even though the eye may not pass over Tampa, tropical storm-force winds extended 230 miles from the center.
Officials were handing out sandbags to residents in the Tampa area, which often floods when heavy rainstorms hit. Sandbags also were being handed out in Homestead, 20 years after Hurricane Andrew devastated the community there. Otherwise, however, convention preparations were moving ahead as usual.
Groups including Code Pink, People for the Ethical Treatment of Animals, the AFL-CIO union and Planned Parenthood have already started arriving in Tampa, regardless of the forecast.
Police said even heavy rain could reduce the protesters' ranks, and could also bring relief from another worry: extreme heat.
Flooding and beach erosion is also a concern for southwest Florida. The hurricane warning included the west coast of Florida from Bonita Beach southward.