A disturbance in the Caribbean expanded into Tropical Storm Rafael on Monday afternoon. The storm is expected to become a hurricane on Tuesday.

Rafael, formerly known as Potential Tropical Cyclone 18, formed on Sunday. As of 4:00 PM ET on Monday, the winds were about 175 miles south of Kingston, Jamaica, with maximum sustained winds of 45 mph, moving northward at about 9 mph, according to the National Hurricane Center ( NHC).

Rafael is the 17th named storm of the Atlantic hurricane season, and will be the 11th hurricane if it continues to strengthen as expected. The season lasts until November 30, although peak activity is usually around September 10.

The storm system is expected to approach the United States later this week, the hurricane center said, and a tropical storm watch was issued Monday afternoon for the lower and middle Florida Keys and for the Dry Tortugas. Parts of Florida and nearby areas in the Southeast could experience heavy rainfall by mid-week, although NHC forecasters say it is too early to make predictions about impacts to the Gulf Coast.

A hurricane warning has been issued for the Cayman Islands and a tropical storm warning is in effect for Jamaica.

The government of Cuba has issued a hurricane watch for a handful of provinces, and a tropical storm watch for other areas.

Forecasters expect the weather system to move near Jamaica late Monday and then near or over the Cayman Islands late Tuesday, at which point it could be near or at hurricane intensity. The country is then expected to approach Cuba on Wednesday.

As early as Monday morning, NHC forecasters said the chance of the storm becoming a hurricane over the next 48 hours would be “nearly 100%.”

Rafael is forecast to dump 3 to 6 inches of rain across much of the western Caribbean, with up to 10 inches in some areas. The heaviest precipitation is expected in Jamaica.

Minor coastal flooding is possible in Jamaica on Monday evening, and storm surge up to three feet is expected in the Cayman Islands on Tuesday, the NHC said. Floods and mudslides may also occur in parts of Jamaica and Cuba.