Watches and warnings were issued Wednesday for Caribbean nations in the projected path of Tropical Storm Isaac, the National Hurricane Center in Miami said. Isaac, with maximum sustained winds of about 45 mph, was becoming more organized and could intensify into a hurricane by Thursday, the center said in its 8 a.m. EDT advisory. The storm was about 210 miles east of Guadeloupe as it traveled west at 19 mph. Tropical storm warnings were in effect for Martinique, Dominica, Guadeloupe, St. Martin, St. Kitts, Nevis, Antigua, Barbuda, Montserrat, Anguilla, Saba, St. Eustantius, St. Maarten, the British and U.S. Virgin Island, Puerto Rico, Vieques and Culebra. Hurricane watches were posted for Puerto Rico, Vieques, Culebra, the U.S. Virgin Islands, the southern coast of the Dominican Republic from Isla Saona west to the Haiti-Dominican Republic southern border. A tropical storm watch was effective for the northern coast of the Dominican Republic from the Haiti-Dominican Republic east to the northern Isla Saona. 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.