Tropical Storm Isaac could threaten Florida

A new tropical storm -- Isaac -- has formed in the eastern Caribbean.

At 11 p.m. Tuesday, the system's center was located at 15.6 North, 55.6 West, about 380 miles east of Guadeloupe with maximum sustained winds of 40 mph.

The National Hurricane Center says Isaac is moving west at 17 mph.

Tropical storm watches are in effect for most of the Lesser Antilles, including Martinique, Dominica, St. Martin, St. Kitts, Antigua, Barbuda, the Virgin Islands and Puerto Rico. A warning means tropical storm conditions are expected somewhere within the warning area within 36 hours.

On the forecast track, Isaac should move through Antilles Wednesday afternoon or evening, emerging in the eastern Caribbean Sea by Thursday, strengthening into a Category 1 hurricane.

From there, it's path is uncertain. Some forecast models have it curling through the Gulf of Mexico and making landfall in Southwest Florida, while others have it staying south of Cuba. If it does wind up heading this way, South Florida could begin feeling Isaac's effects as early as Sunday, forecasters say. It could also disrupt the Republican National Convention in Tampa next week.

The National Hurricane Center also is monitoring a separate disturbance in the eastern Atlantic, giving it a high chance of developing. Models indicate that system will trek northwest over the next five days.