Tropical Storm Melissa crawled through the Caribbean Thursday morning, moving at just 3 mph as officials warned the storm could rapidly intensify into a Category 4 hurricane by next week.

The National Hurricane Center reported Melissa was located about 240 miles southeast of Kingston, Jamaica, with sustained winds near 50 mph. Hurricane watches are in effect for Jamaica and parts of Haiti, with tropical storm warnings issued for Jamaica.

The United States mainland is not completely out of the woods, but a direct hit looks unlikely. If Melissa takes longer to turn north, it could bend toward eastern Cuba or the Bahamas before curving into the Atlantic. Rough surf and rip currents could spread along the U.S. East Coast next week.

The storm’s slow movement poses the greatest danger to the region. Melissa is forecast to bring 10 inches of rain across southern Haiti, the southern Dominican Republic, and eastern Jamaica through the weekend, with isolated areas seeing more than a foot of rainfall.

The National Hurricane Center warned that heavy rain could bring significant flash flooding and dangerous mudslides across the three countries. The storm is expected to reach hurricane strength by the weekend and likely become a major hurricane—Category 3 or greater—by Monday.

Three of the four Atlantic hurricanes this season underwent extreme rapid intensification: Erin, Gabrielle, and Humberto. Melissa could follow the same pattern as it moves over exceptionally warm Caribbean waters that have been untouched by any hurricane or tropical storm so far this year.

Melissa is the 13th named storm of the 2025 Atlantic hurricane season and the first to form in the Caribbean Sea this year. The Atlantic hurricane season runs through November 30.