MIAMI - The lower and middle Florida Keys are now under a tropical storm warning as Tropical Storm Rafael is forecast to grow steadily as it churns past Jamaica's west coast on a path for Cuba, where it's expected to arrive later in the week as a hurricane.

Tropical Storm Rafael is forecast to become a hurricane in the northwestern Caribbean near the Cayman Islands before making landfall in Cuba.

The National Hurricane Center forecasts Tropical Storm Rafael to grow into the season’s 11th hurricane on Tuesday as it moves toward Cuba with winds and storm surge expected to affect the Florida Keys this week.