Tropical Storm Erika moved steadily toward the Leeward Islands on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Erika was located at latitude 16.7°N and longitude 60.2°W which put it about 110 miles (175 km) east-southeast of Antigua and about 1400 miles east-southeast of Miami, Florida.  Erika was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1006 mb.  Tropical Storm Warnings have been issued for Anguilla, Saba, St. Eustatius and St. Maarten, Puerto Rico, U.S. Virgin Islands, British Virgin Islands, Montserrat, Antigua, Barbuda, St. Kitts, Nevis, St. Martin and St. Barthelemy.  Tropical Storm Watches have been issued for the coast of the Dominican Republic from Cabo Engano to Cabo Frances Viejo, the southeastern Bahamas and the Turks and Caicos, and Guadeloupe.

Although Erika looks very impressive on infrared satellite images with a large area of cold cloud tops, it is in reality very poorly organized.  The thunderstorms generating those cold clouds are located southeast of the low level center of circulation.  There are not really any thunderstorms in other parts of Erika.  There could be a mid-level center of circulation within the cluster of thunderstorms southeast of the surface center.  Well organized tropical cyclones are vertically stacked with the mid-level center directly above the surface center.  This is certainly not the case with Erika.  Upper level winds from the west appear to be causing vertical wind shear over Erika and that is contributing to the poor organization.

Erika is moving over water where the Sea Surface temperature is almost 29°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, an upper level trough over the central Caribbean Sea could continue to cause wind shear over Erika.  The intensity guidance is inconsistent.  Some guidance strengthens Erika to a hurricane during the next few days, while other guidance weakens it.  Until the circulation become more well organized and thunderstorms develop near the center of circulation, significant intensification is unlikely.  If the vertical wind shear gets any stronger it could weaken Erika to a tropical depression.

The track forecast is also challenging.  The numerical guidance shifted the track toward the east on Wednesday evening, but that was due to the fact that the models were predicting that Erika would become a stronger hurricane.  If it become a stronger storm with a taller, vertically coherent circulation, then the upper trough over the Caribbean could push Erika farther east.  However, if Erika remains weaker, then the winds in the lower levels of the atmosphere could push it farther to the west.  On its anticipated track Erika could approach southeastern Florida in about four days.