Tropical Storm Danny, downgraded as its wind speeds dropped, is now moving west at 15 mph (24 kph) with sustained winds of 50 mph (80 kph). As of 11 a.m. ET Sunday, it was 275 miles (442.5 kilometers) east of Guadeloupe in the Lesser Antilles. Strong winds extend some 60 miles (96.5 kilometers) from the center.

The storm is expected to track through the Leeward Islands in the Caribbean over the next 24 hours, according to the National Hurricane Center. Rain from 2 to 4 inches could fall as the center moves over the islands Sunday night or early Monday. It is forecast to continue moving northwest over the next five days.

Danny is not expected to intensify. Weather models show the storm weakening to a tropical depression or wave by day five. However forecasters warn that conditions can change quickly and say they will be monitoring closely.

Tropical storm warnings are in effect for Antigua, Barbuda, Montserrat, St. Kitts, Nevis and Anguilla.

A tropical storm watch it in effect for Puerto Rico, Vieques, the U.S. Virgin Islands, Saba and St. Eustatius, St. Maarten, and Culebra.

Tropical storm watches have been discontinued in Guadeloupe, St. Barthelemy and St. Martin.

According to the National Oceanic and Atmospheric Administration Climate Prediction Center, which has updated its 2015 Atlantic hurricane season outlook, there is a 90% chance of a below-normal hurricane season this year.

Of the six to 10 named storms expected for the 2015 season, only one to four are likely to become hurricanes.

There's an even smaller chance that one of these storms will transform into a major hurricane, defined by the National Hurricane Center as any storm that is Category 3 -- with sustained winds of 111-130 mph (96-113 kt or 178-209 kph) -- or higher.

For almost a decade, the United States hasn't seen a hurricane greater than a Category 3, putting it in a nine-year major hurricane "drought."

It has been the longest period to pass without a major hurricane hitting the United States since reliable record-keeping began in 1850, a 2015 NASA study said.

Hurricane Arthur, a Category 2 storm, was the last hurricane to make landfall in the United States when it came ashore in July 2014 between Cape Lookout and Beaufort, North Carolina, according to the National Hurricane Center.

CNN's Melissa Gray contributed to this report.