IWIC Atlantic Tropical Weather Discussion 11:00 PM EDT, August 25, 2003
General Pattern: Conditions are favorable for development across much of the Gulf of Mexico and Caribbean Sea. An upper level trough is enhancing upper level winds between 25N-30N from 80W eastward. the Saharan Air Layer is a dominant feature between 35W-50W. Upper level winds are favorable across much of the Mean Development Region (the area between the Lesser Antilless and Africa).
Gulf of Mexico: A westward moving upper level low located near Oaxaca, Mexico is enhancing upper level winds over the Bay of Campeche and also across the Yucatan. Convection has increased over land due to the upper feature. The convection is nontropical. A mid-level circulation visible on water vapor imagery is located just west of Florida. It will drift westward over the next 4-5 days before being drawn northward into Louisiana. No development is expected. the remnants of Tropical Depression Nine in the northwest Caribbean will drift westward into the Yucatan. Regeneration is highly unlikely.
Caribbean Sea: One area worth monitoring is a tropical wave moving just south of Hispaniola. Convection has been on the increase the past six hours and QuikSCAT data shows that a low level circulation may be located just east of the strongest thunderstorm activity. A ridge of high pressure aloft is located directly over the wave. Some shear is present along the eastern edge of that ridge, possibly forcing most of the thunderstorm activity just west of the center....not enough to inhibit slow development. The problem is that the wave has been moving west-northwest towards Hispaniola and Cuba. The global models are in agreement with a track into the Bahamas. But that is another problem. there is an upper level trough situated across the western Atlantic. Vertical shear levels in this are not expected to decrease anytime soon. If the WNW track were to continue, and the model forecasts verify, the chances of development would be almost impossible. However, the wave does have a shot. As I have mentioned the past several days, low level steering winds in the northern Caribbean are coming straight out of the east. This would support the idea of a more westerly track just south of Hispaniola and Cuba. This is why the remnants of TD9 continued moving more westward. Also remember that the models had a northerly bias. Model data indicates that upper level winds may be a bit more condusive for development in this area. The latest infrared loop shows that there may be a slightly more westerly motion. I would like to see if this trend continues over the next 6-12 hours.
Atlantic Ocean: A weak tropical wave near 40W has shown no signs of development. The SAL and subsidence will prevent development from this wave.
A more impressive tropical wave exited the coast of Africa within the last 24 hours. There is a good amount of moisture for the wave to work with and upper level winds appear to be favorable for slow development. Water vapor imagery does show a slight increase in subsidence northeast of the MLC which is located near 11N/20W. This may inhibit development over the next 24 hours. The overall structure remains impressive so it must be watched as it moves westward.
There are some indications that we will see a spike in activity during the first week of September. The negative phase of the Madden Julian Oscillation is expected to move into the Atlantic Basin at around that time. the North Atlantic Oscillation should still be negatibe by the time the MJO moves in. In addition, the SOI has gone negative. Sometimes this is an indication of Atlantic development 8-10 days down the road. We have a long way to go. We're currently in a short lull before the real activity begins.
For a basic and general rundown, refer to our tropical weather outlook. These are unofficial products, and are not from the NHC.
Forecaster: Moreland
Comments?
..as always great JOB!!! 
