An area of disturbed weather in association with a weak surface trough and a stronger upper-level trough between the Bahamas and Bermuda developed on September 6.[2] High pressure ridging strengthened by Tropical Storm Fay caused the trough to become more organized and close off into a broad non-tropical low on September 7.[2] By September 8, the system had developed enough convection near its center of circulation to be classified Subtropical Depression Eight while located southeast of Cape Hatteras, North Carolina.[2] Later that day, data from a Hurricane Hunter reconnaissance aircraft indicated that the system had strengthened into a subtropical storm, and the depression was upgraded to Subtropical Storm Gustav.[3]