Tropical Storm Rafael is passing south of western Jamaica and is forecast to strengthen into a hurricane possibly by Tuesday evening.Rafael, which formed Sunday and was previously known as Potential Tropical Cyclone 18,

Rafael is forecast to strengthen Tuesday and will likely become a hurricane over the next 24 hours as it batters the western Caribbean on the first leg of an uncertain journey toward the US Gulf Coast.

Tropical Storm Rafael is intensifying as it moves toward the Cayman Islands and western Cuba. It will likely enter the Gulf of Mexico as a hurricane - here's what you need to know.