weathernet
(Storm Tracker)
Tue Sep 02 2008 06:10 PM
Re: Concern

uh oh...., speaking of models, am curious to see if in light of the GFS now swinging more to the left with its 12Z run, if in fact the GFDL runs today will follow suit.

For the moment however, the latest NOGAPS ( as of 12Z today ) now shows Hanna closer and just off shore ( approx. 79W ? ) the greater Miami/Ft. Lauderdale area, and basically making landfall somewhere around W. Palm Beach, moving WNW'ward and sitting over Lake 'O in 66 hr's. This as well, is a swing to the left from both the 0Z and 6Z run. Of course, next run could be entirely the opposite.................. or greater confirmation of a possible trend to the left. More importantly, will wait and see if other models trend more westward or not.

My guess would have involved a more westward track in the short term, due to steering being controlled more by the lower levels. In fact, what "may" occur, might be this. NHC has duly been predicting a NW motion primarily caused by Hanna being at a point, where a large and strong 594mb mid level Atlantic ridge would be practically forcing a motion towards the NW. This high has been migrating westward across the Altantic, and will continue to do so, especially as a trough off Nova Scotia eventually pulls up and out of the picture. I believe that as such, the orientation of this mid level high would have already started impacting Hanna by now. However, perhaps either by northerly 200-300mb winds aloft ( which impact shear, and much less motion ), or simply because Hanna is simply somewhat more of a shallow system due to the very shear it is fighting, this very delay in the projected NW motion, even if by 12 or 24 hours, might just cause enough of a delay so that the orientation of the building W. Atlantic ridge, might just start filling over and north of Hanna enough, then rather than an outright NW motion to ensue, we might eventually start seeing a similar but more WNW motion instead. Almost as if a storm were rather "indented" into the lower left quadrant of a westward migrating ridge, rather than simply rounding the corner of it. If this theory were correct, than I would presume that once such a motion were to start, it might be fairly slow steady motion until once again, Hanna were to round the perifiery of the high, only then.....to turn more poleward.

This scenario, whether if exact or just causing the official forecast to be tweaked more westward, would seem to place Hanna too close to the lower Florida southeast coast than exact forecasting error would allow for error. Therefore, and purely assuming that model guidance does shift more westward, and more importantly, assuming that Hanna does track a little bit more west or WNW'ward......., I cannot help but imagine that Tropical Storm Watches would have to go up perhaps as early as late tonight for at least the Palm Beach coastline, and possibly even south from there. Naturally the longer any delay in Hanna's motion were to continue, than the the less likely Watches would be necessary until perhaps tommorrow.



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