Complex sentence: Shortly after Arthur became a tropical storm on July 24, a tropical storm warning was issued for Trinidad, Tobago, and Grenada; six hours later, it was extended to the Grenadines.
Split into simpler sentences: Shortly after Arthur became a tropical storm on July 24, a tropical storm warning was issued for Trinidad, Tobago, and Grenada. Six hours later, the tropical storm warning was extended to the Grenadines.