| typhoon_tip |
| (Meteorologist) |
| Mon Sep 03 2007 02:34 PM |
Re: Region of interest just off the SE U.S. Coast
|
Update...
Convection persists in associating with the area of disturbed weather situated along the tail end of a slowly decaying frontal boundary, which extends seaward from approximately 50miles east of the central Georgia Coast. Nestled in this vicinity is a region of slightly improved cyclonic organization.
The general parameters are essentually unchanged for now:
Oceanic heat content is large in that vicinity -- positive
Upper air analysis suggests evolving divergent vectors in the 200mb level -- positive
Pressures remain high in that region -- negative
Forecast models:
They are showing trends toward a converged opinion as of the 12z run this morning, that this region will likely continue to evolve and eventually lead to a Tropical Depression. Models typically will not perform stellar during the genesis phase of any given TC (Dean was a startling exception rather than the rule), so timing the birth of this feature is inherently going to be low skill. The general consensus of the models is to drift a beta low toward the east-southeast where it will slowly gather purer tropical characteristics. By 72-84 hours, the NAM has a depression centered near 70/30. (*The NAM is a low skill predictor for tropical weather phenomenon) This is intriguing because the GFS also places a similarly defined system at that location and time; from that point forward in time, it then shows a west movement with some implications for development as it approaches the Eastern Seaboard by as near as 120 - 132 hours. The most glaring solution is that of the CMC, which shows also this similar solution through 84 hours as the GFS and NAM, but then it does something interesting: It bombs this into an intense hurricane and has it moving due N about 50 to 100 miles east of Cape Hatteras, NC, by 132 hours. (*The CMC is also a low skill predictor for tropical weather phenomenon, tending to over-production). The 12z ECM is also now developing this system close to the same location as the NAM, GFS and CMC, and in similar timing. It also shows it moving back west and at least implies intensification. I have not seen the 12z UKMET.
Visible imagery is showing a general albeit weak for now, cyclonic motion, with some indication of a mid-level circulation displaced east of the weakly discernable broad low level rotation. However, given to:
The persistence of convection and on-going phase transition from barolcinic to barotropic
The favorable parameters discussed
The emerging model consensus
slow development is quite plausible if not likely. Can never be certain about these things.