Simplify the following text for a Grade 12 native English-speaking person.
Original: Hurricane Katrina formed as Tropical Depression Twelve over the southeastern Bahamas on August 23 , 2005 as the result of an interaction of a tropical wave and the remains of Tropical Depression Ten .
Simplified: Hurricane Katrina began as Tropical Depression Twelve over the southeastern Bahamas on August 23 , 2005 .