Well, I don't have a hard pat answer for your question at this time, and I would really like to give credit to Clark's post forgiving me this theory...so if I happen to go astray/wrong, I hope he sets me straight.

At this time, Erin is no longer a tropical cyclone. However, the remanants of Erin continue to be that of a warm core low pressure system. Until the remanants of Erin phase out, it will continue to transport warm air and moisture to the upper levels. At this time, Erin's remenants are doing just that. It is this warm air and moisture that I conclude is pumping up the ridge (Keeping it strong enough) to have a blocking effect on the Upper Level Low over the Bahamas. In other words, keeping the ridge strong enough to prevent the Bahamas low from moving westward as quickly as expected by the models.

Itis tough to say when Erin will phase out for sure. In general, I am taking the entire interaction of the Atlantic Ridge, the Bahama's Low, the Gulf States Ridge and other weather features on a 24 hour by 24 hour basis. Now is as good of time as ever to sound like a broken record that we've all heard before.Models are not perfect science here when looking 3,4 or 5 days out folks. However, it is the best tool that the professionals have in making educated decisions. If you all remember correctly, when Dean First developed, the models had a pretty good handleon taking this storm across the NE corner of the Leewards and back into the SW Atlantic. That did not happen and the current 5 day forecast may likely be just as inaccurate, Likewise, it may be very accurate (just as we've seen on many previous storms). For now, do not put all ofyour eggs in one basket on the day 3,4,5 model plots. Dean is far enough away that everyone can be in a monitoring phase (on a 24 by 24 hour basis) and be aware that the upper level low over the Bahama's may have an effect on Dean after all if it continues to retrograde as slowly as it is right now. I know, lot'sof unanswered questions, but this is the best way to approach the future of Dean right now.