Simplify the following text for a Grade 6 native English-speaking person.
Original: As the system moved to the west , it strengthened gradually , becoming Tropical Storm Ivan on September 3 and reaching hurricane strength on September 5 , 1,150 miles ( 1,850 km ) to the east of Tobago .
Simplified: Tropical Storm Ivan moved to the west and on September 5 it became a hurricane .