That's a funky soulution that the 06Z GFDL has, having Katrina take a sharp left turn before hitting the east coast of Florida, then getting a ways out into the Gulf. Also interesting to note that after not even strengthening the system to a tropcial storm through the 00Z run, it now strengthens it into a cat 2 hurricane before reaching the far SE coast of FL and then blows the system up into a major hurricane over the Gulf in the 06Z run.

Considering the unrealistic looking SW turn of the storm in the model, the solution has to be considered suspect at best, but it illustrates how little changes can make huge differences in the models, especially for tropical systems.

--edited to change cat 1 to cat 2 in first paragraph