Simplify the following text for a Grade 7 native English-speaking person.
Original: The 13th named storm of the 2008 Atlantic hurricane season , Marco developed out of a broad area of low pressure over the northwestern Caribbean during late September 2008 .
Simplified: It was the 13th named storm of the 2008 Atlantic hurricane season . Marco started from a large storm over the northwestern Caribbean Sea during late September 2008 .