Additional explanation for why the Upper Level Low over the Bahamas is not moving as much as expected:

In my previous post, I indicated that yes, while the ridge to the north of Dean is nudging at the Upper Level Low over the Bahamas from the east, the high over the Missippi Valley/GA (Which extended southward into the northern half of the Gulf and the Western Guld Coast States) was also pushing back from the west. Inhibiting the Bahamas Cutoff Low and southward extending TUTT like feature from retrograding westward as quickly as indicated.

It does look reasonably apparent that Erin may have helped to pump up the intensity of the Missippi Valley Ridge and may be continuing to do so. I would like to revisit a post from Clark that he made yesterday... Also, here is a repost of the Water Vapor Link for the Entire Atlantic Basin: http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html

Quote from a FL Hurricane Poster:
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About the only way that Erin could affect dean is if it weakens the high pressure system developing over the central US that is going to cut Dean off from an east coast hit and help force it into the gulf.

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Clark's Answer:
Well, it could also help to strengthen that high pressure ridge (due to the warming at upper levels from its convective outflow), resulting in impacts on the pattern further to the east. It's kinda like the case of a recurving system leaving behind a weakness to cause other systems to recurve days later, except the reverse scenario. Granted, in this case, it's likely to be a very small impact -- but probably still a noticeable one.

(Edit -- on retrospect, I see that this also helps answer the question posted by "tumbleman" in the second post in this thread. If they would like more info on this, please reply and explain.)