MIAMI, Florida (Reuters) -- Tropical Storm Debby steered over the open Atlantic well away from land Thursday while a band of squalls in the southeastern Caribbean threatened to coalesce into a new tropical storm.
Forecasters at the U.S. National Hurricane Center said the latest Caribbean weather disturbance was pelting the Windward Islands with gusty rain and could soon become Tropical Storm Ernesto.
"It's very, very close to that threshold now," said James Franklin, a senior hurricane specialist at the center.
An Air Force reconnaissance plane was flying out to check whether that system's sustained winds had reached a strength of 39 mph needed to become a named storm.
In the eastern Atlantic, Tropical Storm Debby -- the fourth of the 2006 Atlantic hurricane season -- had top winds of 50 mph. Forecasters expected it to strengthen gradually, possibly becoming the season's first hurricane in about three days.
It would become a hurricane if sustained winds reach 74 mph.
But as Debby moves over warmer waters that add fuel to tropical cyclones, it will also encounter sheering winds that could rip it apart.
Regardless of what happens, Debby's most likely path kept it over the open Atlantic, where it was only a threat to ships, forecasters said.
Debby was about 955 miles west-northwest of the Cape Verde Islands and moving west-northwest at 20 mph. It was expected to curve to the northeast early next week, away from the United States.
The current June 1 to November 30 Atlantic hurricane season has been fairly quiet, but storm formation typically ramps up during the peak mid-August to late October period.
Last year produced a record 28 tropical storms and hurricanes. Katrina devastated New Orleans and killed about 1,500 people along the Gulf coast, according to the latest estimate by the hurricane center.