Chantal weakening in Caribbean

MIAMI, Florida (CNN) -- Chantal, the Atlantic's third tropical storm of the season, was weakening Thursday night into a strong tropical wave off the Windward Islands in the Caribbean.

All watches and warnings for the islands of the Lesser Antilles were discontinued, except for a tropical storm watch for Martinique and Guadeloupe. That watch is scheduled to be discontinued at 8 a.m. EDT Friday.

Forecasters have been keeping a close eye on Chantal, which early Thursday had been upgraded from an unnamed tropical depression. But reports on Thursday night from a U.S. Air Force "hurricane hunter" plane indicated that Chantal no longer had a center of circulation, the National Weather Service said.

CHANTAL INFORMATION At 8 p.m. EDT Thursday POSITION 13.0 north latitude 61.0 west longitude Near St. Vincent in the Windward Islands MOVEMENT West at near 29 mph (47 km/hr) WIND SPEED 40 mph (65 km/h) in a few squalls EXTRA INFORMATION In-Depth: Hurricanes     RESOURCES On the Scene: Chad Myers: Chantal expected to develop into hurricane

At 8 p.m. EDT (0000 GMT) Thursday, the dissipating center of Tropical Storm Chantal was near St. Vincent in the Windward Islands. The wave was moving west at near 29 mph (47 km/h), with a rapid westward movement expected for the next day or so.

Chantal was carrying maximum sustained winds of near 40 mph (65 km/h) in a few squalls.

A tropical depression becomes a tropical storm when its sustained winds reach 39 mph (63 km/h), and a storm becomes a hurricane when its winds reach 74 mph (98 km/h).

Tropical storm force winds extended 115 miles (185 km) from Chantal's center.

Rainfall amounts of 2 to 4 inches, with locally higher amounts in mountainous areas, were still possible over some of the Lesser Antilles, the National Weather Service said.

The Atlantic has not yet seen a hurricane this season, which began in June. Two tropical storms, Allison and Barry, made landfall along the northern Gulf Shore of the United States with heavy rains and flooding.

Allison's 12-day march from Texas to New England left 35 people dead and caused more than $1 billion in damage.