Weather forecasters say Tropical Storm Delta has winds of 104 kilometers per hour and is gaining strength in the central Atlantic. The storm could become a hurricane later Thursday.

Meteorologists designate storms with winds stronger than 119 kilometers per hour as hurricanes.

Tropical Storm Delta formed late Wednesday. At last report, it was located about 18,000 kilometers southwest of the Azores Islands, and was not a threat to land.

Delta is the 25th named storm of this record-breaking Atlantic hurricane season, which runs from June 1 to November 30.

Forecasters began using Greek letters to name the storms after they ran through their usual list of names in English.

Some information for this report provided by Bloomberg and Reuters.