At 15Z today, advisories resumed on what was TD10 during the weekend. It had degenerated into an open wave on 9/15 at 21Z (as determined by visible satellite imagery and aircraft recon). Those same tools assisted in the recent upgrade. Deep convection has been remarkably persistent with this system, and there are now hints of what appear to be spiral bands trying to form. It is in 15kts of deep (850mb-200mb) SW shear, and the convection being displaced to the east of the center is one visible sign of that. The SST there is slightly warmer than 29C, which no doubt has been the cause for the copious convection (a lot of heat energy being supplied to it). The 15Z advisory places TD10 at 15.9N 77.2W (about 200km south of Jamaica) and tracking W at 8kts. Intensity is 30kts and 1009mb. The shear is marginal for development now, but it is expected to lessen, and combined with the warm SSTs, the storm should be able to intensify in the near future. Interaction with the mountains islands in the Greater Antilles may keep intensity down for the next couple days, but the forecast track is one that could give the storm plenty of time to get its act together. NHC's forcast is for gradual strengthening, just shy of being a hurricane by Friday morning, but admitedly, a lot can change in a short time. If named, it will become Isidore. Nearly all models keep the center south of the Greater Antilles (which include Cuba, Jamaica, Hispaniola, and Puerto Rico) and take the system between the Yucatan Peninsula and Cuba by Friday morning... in perfect position to enter the Gulf. GFDL is perhaps the quickest landfall model of the bunch, bringing the storm into the Tampa area on Saturday afternoon as an 80kt hurricane. If the storm is allowed to enter the Gulf, it would spend 2-3 days there (basically the weekend) and perhaps strengthen quite a bit. Remember the key to hurricanes in the Gulf... they almost have to make landfall somewhere. Elsewhere, there is a vortex with moderate convection at 33N 53W. Although formed from an upper-level Low, a surface circulation has developed and is taking on tropical characteristics. If further development occurs, it could be upgraded to TD11.
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