Tropical Storm Isaac is forecast to become a hurricane and may impact the Republican National Convention, meteorologists said Wednesday. Watches and warnings were issued Wednesday for Caribbean nations in the projected path of the storm, the National Hurricane Center in Miami said. Meteorologists expect Isaac to curve northward, toward Florida and the southeastern United States next week, coinciding with the Republican National Convention in Tampa, Fla., said Alex Sosnowski, senior meteorologist with Accuweather.com. Isaac, with maximum sustained winds of about 45 mph, was becoming more organized and could intensify into a hurricane by Thursday, and a hurricane watch was in effect for Puerto Rico, the Dominican Republic and the U.S. and British Virgin Islands, the Weather Service said in its 2 p.m. EDT advisory. The storm was 75 miles east-northeast of Dominica and 95 miles ease-southeast of Guadeloupe, approaching the Leeward Islands as it traveled west at 21 mph. Isaac was expected to maintain its westerly course for the next couple of days, forecast to pass through the Leeward Islands Wednesday evening and move over the northeastern Caribbean Sea Thursday, the center said. Tropical storm-force winds extended outward from Isaac\'s center up to 45 mph. Isaac could generate 4- to 8 inches of rain over the northern Windward Islands and Leeward Island, the center said. Puerto Rico and the Virgin Islands could get 1-3 inches of rain with up to 6 inches possible.