The 6z GFS (and recent runs) have been showing a tropical system forming in the Caribbean/Gulf of Mexico regions around the 18th. This system would likely be a very weak hurricane at best, with weak central pressure but high precipitation. The system would first make landfall in Florida.
Following the Florida landfall, the same system would restrengthen in the far western Atlantic just off Georgia and hit southern Carolina, likely as a weak tropical storm. This poses a threat for flooding if it were to verify, and some flood control systems may be put under unusual stress from this tropical system if it were to happen. That is unlikely, however, due to the drought in place over Florida and South Carolina.
However, what the 6z GFS itself is showing pales in comparison to what the ensembles are showing.
This is one of the stronger ensembles of the 6z GFS. It is depicting a 986mb tropical cyclone to make landfall in Florida. This would probably be a fairly strong hurricane. Not major, but 986 millibars is on the stronger side of the Category 1 hurricane spectrum. You can find links to the GFS ensembles by clicking here.