Tropical Storm Rafael is producing heavy rain over islands of the Caribbean as it slowly increases in strength, forecasters said. At 2 p.m. EDT Saturday, the storm was 100 miles southeast of St. Croix, moving north at 9 mph with maximum winds of 40 mph, the National Hurricane Center in Miami reported. Rafael is forecast to drop 3 to 5 inches of rain over the Lesser Antilles, the Virgin Islands, Culebra and Vieques, with as much as 10 inches possible in some areas. Dangerous surf conditions are possible in the Lesser Antilles and the Virgin Islands through Sunday, forecasters said. The center of Rafael is expected to be over the Virgin Islands by Saturday night. Tropical-storm force winds extend as far as 175 miles, mainly to the southeast of the center. Some strengthening of its winds is expected within the next 48 hours. Tropical storm warnings are in effect for much of the Caribbean, including Anguilla, Barbuda, St. Kitts, Nevis, Antigua, Montserrat, Guadeloupe and many of the smaller islands. Puerto Rico is under a tropical storm watch. The storm is expected to turn toward the north-northwest by Saturday night and continue in that direction through early Monday.