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. 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. 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. 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.