Simplify the following text for a Grade 12 native English-speaking person.
Original: On September 23 the area of low pressure moved over the Yucatan Peninsula and was creating thunderstorms from the southern Gulf of Mexico to the northwestern Caribbean Sea .
Simplified: On September 23 the area of low pressure moved over the YucatÃ n Peninsula and was producing thunderstorms from the southern Gulf of Mexico to the northwestern Caribbean Sea .