Simplify the following text for a Grade 13 native English-speaking person.
Original: During the summer months , tropical waves can extend northward as far as the desert southwest of the United States , producing spells of intensified shower activity embedded within the prevailing monsoon regime .
Simplified: During the summer months , tropical waves can go northward as far as the desert southwest of the United States , producing spells of intensified shower activity surrounded within the current monsoon area .