What drives this unusual phenomenon?
Look carefully at the abnormally low temps and low humidity for Gainesville, Florida and Valdosta, Georgia US on the 9th of August, 2002.
It isn’t a cold front, it isn’t even widespread, and the wind isn’t blowing Northwest it’s blowing out of the Northeast and the East
https://www.wunderground.com/history.../date/2002-8-9