I don't see the path for this thing to go significantly eastward (e.g. a loopback towards the FL peninsula - or really anything much east of Mobile.)

I just went through the expected pattern evolution for the next 48 hours, looking at the expected features over the US, in conjunction with the 4pmCDT advisory. Right now you can see the trough very clearly on the WV loop, along with the weakness on the tail end of it as it dives southward.

(I use the Unisys links for GOES, which can be had at http://weather.unisys.com/satellite/sat_ir_enh_se_loop-12.html - from that link you can select WV, IR, Vis, which bird and which view, looped or single image. All in one place, very nice...)

Forecast is for that trough to lift out to the NE over the next 36 hours, leaving a weakness ahead of a second feature that is moving in across roughly the TX/OK boundary aproaching from the west. That gap looks to be roughly aligned right over the north of the system in 48 hours - right about when the forecast is for landfall. Ths is a clear weakness in the overall pattern and I see no reason for Katrina not to move into the gap, and then be forced NNE as the trailing feature moves east.

For the storm to move to the NE, the trough currently over Tennessee would have to dive further south than forecast and fail to lift out to the NE over the next 36 hours. If that was to occur then there would be a gradient that would lift Katrina to the NE - which is the scenario that some here are positing.

But - the northeast edge of that trough is already starting to fold up and back - clearly visible on the WV loop. For the trough to continue to hold its strength through the forecast period with that sort of presentation would be pretty odd at this time of year - you might see that in November, but not in August.

I'm not buying it. The high that was feeding dry air into the core from the north is basically off the table, which is why you're seeing the north and northeast quadrants explode. They were being inhibited by this inflow, and its gone. The relaxing of that influence is also what is picked up by the models in allowing the movement to the NW and North.

I buy the models at this point, absent some truly extraordinary changes in the overall pattern in the next 24 hours. If anything I'm seeing a bit east of the NHC's track, but not by much - and probably not terribly material in terms of those who are "under the gun."

In short, the cone looks good to me.... but with this system being as large as it is, the exact center isn't the issue - if you're within 100nm you're going to get some NASTY weather, especially to the east.