One fine mess -- that sums up best what we have just off of the southeast coast of the United States this evening. It's my job to try to make some sense of it -- and I think I can do just that.
The main feature of interest is located at about 26N/78W as of midnight ET Wednesday morning, where a mid-level vortex with a developing surface circulation is moving toward the north-northwest paralleling the Florida coastline. Deep layer easterly flow at the surface across much of the western Atlantic associated with a strong surface ridge of high pressure coupled with relatively low (1005-1007mb) pressures over the northern Bahamas are creating winds to minimal tropical storm force on the north and east side of the complex.
The feature has become better organized around this mid-level circulation this evening and is a candidate for development in the next 12-24hr as it moves generally toward the northwest. As Stan has moved inland and weakened, the impacts from the outflow jet associated with the former hurricane and upper-low to the west of the tropical disturbance are lessening through time. However, the upper-low is contributing to somewhat of unbalanced convective distribution with most of the convection on the east side of the disturbance; at the same time, it is also serving to enhance said convection through upper diffluence (winds moving apart from each other on a horizontal surface). Surface water temperatures have recovered somewhat from Ophelia's passage but remain near 27-28C, nowhere near their peak earlier this season.
I expect the system to develop into a tropical storm upon investigation by the reconnaisance aircraft early tomorrow afternoon and strengthen marginally as long as it remains over water. Movement is expected to be toward the north-northwest, bending back toward the northwest in the next day or so. Primary landfall target is from Cape Canaveral, FL northward to Savannah, GA within 36-48hr as a moderate tropical storm. The primary steering influence for this one appears to be the upper-low over the northern Gulf with the northward movement of the system blocked by a progressive upper level ridge of high pressure centered over the mid-Atlantic states.
On that trajectory, the system would not reenter the Gulf of Mexico. My feeling is that the main energy from this system, whether or not it develops, will move inland across south/central Georgia until it is picked up by a deep trough projected to move into the eastern US over the next couple of days. A small piece of energy may cut-off from the system and move out over Gulf waters, but under the shearing environment associated with the approaching trough is not likely to be a candidate for tropical development. Elsewhere, the trailing end of this complex near Puerto Rico looks relatively impressive, but I feel that much of its energy will become caught in a deep trough over the central Atlantic and is not a candidate for development over the next few days. Some of the low-level energy may eventually feed into the developing disturbance near the Bahamas, but that's about all. This trough, extending down to 15N and out to 40W, pretty much spells the end of Cape Verde season. I'm not buying the spurious tropical storm the continually develops are recurves between 20-25W in the next couple of days; conditions are marginally favorable near Africa, but this wave is likely to meet the same fate as the last ten or so.
The remnant of Stan presents an interesting dilemma for both basins. While the main circulation is well inland over the skinny part of Mexico, fringe mid-level convective complexes -- one in the East Pacific along the Mexican shore and another over the Yucatan and in the Bay of Campeche in our basin -- may serve as the focus for development within both basins. In the East Pacific, the remnant low of Stan may merge with this mid-level convective complex to its west and develop into a tropical system that hugs the coast; whether or not it would retain the name Stan depends upon whether or not Stan remains classified throughout the period. In our basin, some of this energy may work its way over the Bay of Campeche and develop in a quasi-tropical or hybrid sense over the coming days in advance of the approaching trough. Anything that develops is likely to remain lopsided and relatively weak; something like Michael last year isn't out of the question. Needless to say, it bears watching.
To sum it all up, I think we'll get our next system out of the disturbance near 26N/78W sometime Wednesday with minimal threats for development -- at least tropically -- across the rest of the Atlantic and in associated with the trailing features lying behind the aforementioned disturbance.
More to come as events warrant.
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