Simplify the following text for a Grade 11 native English-speaking person.
Original: A tropical storm is an organized system of strong thunderstorms with a very clear surface circulation and maximum sustained winds between 17 and 32 m\/s ( 34 â `` 63 kt , 39 â `` 73 mph , or 62 â `` 117 km\/h ) .
Simplified: A tropical storm is an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds between 17 m ( 39 m ) and 32 m ( 73 m ) .