Nice graphic and analysis:

The image and the following are from Tomer Burg (@burgwx):

The majority of ensemble members can be generally split into 2 scenarios:

- TD #9 quickly recurves & tracks up East Coast

- TD #9 slows down in eastern Gulf

One of the sources of forecast uncertainty is TD 9's short-term evolution itself. We can see that short-term latitude strongly correlates with longer-term longitude - meaning a further south TD 9 in the short term tends to track farther west in the Gulf of Mexico.

The trough itself is an important part of the equation too. The EPS have been consistently east of the GEFS & more inclined to recurve. The EPS not only have TD 9 farther east, but also have a deeper & slower NE US trough.