Original: On August 13, while located near the northwestern Bahamas, a substantial increase in convection resulted in the upper-level low building downwards to the middle levels of the troposphere, coinciding with the development of an upper level anticyclone.
Simplified: On August 13, while located near the northwestern Bahamas, an increase in convection made the upper-level low building downwards to the middle levels of the troposphere, which caused the development of an upper level anticyclone.