Once Earl makes it into the same area Charley was, historical maps look like this:
One model last week initialized Charley wrong (didn't read the trough strength right) and put it off the TX coast as a Category 4/5 storm (Click Here for Image). That forecast was based mostly off storm speed and water temperatures (which will both be similar for Earl). If windshear is light (it looks like it will be) and Earl can slow down from it's current speedy track, he will certainly be one to watch carefully.
So, assuming that no major frontal system works into the Gulf (it does not appear likely). Charley will likely enter the south central GOM by late Thursday or Friday. It should be a category 1 or 2 at that time and will have a big pool of quite warm water ahead of it. Hurricanes often do weird things around the Yucatan Peninsula so it is difficult to say what the real world consequences in the US will be.
The model that did the best with Charley takes Earl to the Yucatan Peninsula in 5 days, it extrapolates into the central GOM by day 6.
GFDL Animation - Press "Fwd" to loop
Danielle looks quite beautiful this afternoon but will affect no one:
