sentences:  Three other ships reported tropical storm-force winds.Humberto was the second of four tropical waves in quick succession in the tropical Atlantic that all eventually became tropical storms or hurricanes; it was preceded by the wave that became Iris, and followed by the waves that became Karen and Luis.It was also the first of three tropical cyclones to form within a 24-hour period on August 21 and 22; Iris formed 12 hours later and Jerry formed 18 hours later.