WEATHERAmerica Tropical Weather Summary, Wednesday Evening, August 29, 2007

[Larry_Cosgrove]

Overview

The Atlantic Basin is suddenly awash in potential for tropical development, with growing threats to the Greater Antilles and North American coastline. there are four disturbances which exhibit signs of acquiring a circulation; a fifth, southeast of Newfoundland, is a cold low which may turn subtropical in character with threats to shipping and (after three or four days) to the British Isles.

Western Atlantic Basin
Disturbance Over The Yucatan Peninsula

Although written off by many forecasters, this feature continues to be well-defined and has exhibited a tendency to gain latitude through redevelopment of the center. Currently passing through areas devastated by Hurricane Dean, the tropical wave should emerge over the Bay of Campeche on Thursday. Steering currents to the north and west of the impulse are pointing toward Texas and Louisiana, and may allow for warm-core cyclogenesis and intensification if the thunderstorm bands can hold together passing over the Yucatan Peninsula.

Evolving Low Over The Gulf Stream

If you look closely at the attached satellite image, you can discern a circulation and vorticity center about 450 miles east of Savannah Georgia. The low is associated with convective remnants of a diffuse frontal structure, and is located over very warm waters suitable for tropical development. With inflow of tropical air from the Caribbean Sea and a weak anticyclone present along its north and west flanks, this system poses a threat to the Florida Peninsula. It is possible that the low could attain depression or named storm status before Saturday morning.

Equatorial Zone East Of The Lesser Antilles

Despite the shearing effects of a weakening TUTT signature to its north and east and ingestion of dry, dust-laden Saharan air, a tropical wave which spun off of the African ITCZ near cape Verde last week is still alive. There are still two impediments to development, however. Dry values surround the impulse, and the convective core is so small that it may be swallowed up by the much larger tropical wave approaching from the east.

Inter Tropical Convergence Zone Over Africa

The attached METEOSAT image shows that the lead impulse along the ITCZ, located close to the cape Verde Islands, is large, well-organized, and....ingesting Saharan dust. Still, the cTw values are not reaching the west or south perimeter of convection, so the circulation center will likely survive and reach warmer waters over the central and western Atlantic Basin. With most of the numerical models showing a vigorous Bermuda High developing over the eastern United States and the Gulf Stream, this feature may eventually pose a threat to the major islands or Florida Peninsula in about 240 hours.

Eastern Equatorial Pacific Theater
Tropical Storm GIL

Gil formed from a convective cluster west of the Mexican Riviera this morning, and is now situated just to the southwest of Cabo San Lucas in Baja California. Gil should begin to weaken on Thursday as it moves into a cooler, stable environment (note the marine layer cloud form to the northwest of the tropical storm), and likely poses no threat to any land area before it breaks up well east of Hawaii in about 72 hours.

[rainstorm]

thanks for the update. this is the peak and we must be alert