A reconnaissance plane investigated the system that was formerly designated Invest 91L on Friday afternoon and the plane found that the system had enough tropical characteristics to be classified as Tropical Depression 2 by the National Hurricane Center (NHC). At 5:00 p.m. EDT on Friday the center of Tropical Depression 2 (TD2) was located at latitude 28.5°N and longitude 74.7°W which put it about 435 miles (695 km) southeast of Charleston, South Carolina. TD2 was moving toward the west-northwest at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h). The minimum surface pressure was 1009 mb. A Tropical Storm Warning has been issued for the coast of South Carolina from the Savannah River to Little River Inlet.
The circulation in Tropical Depression 2 became better organized on Friday, but it would not yet be considered well organized. More thunderstorms formed near the center of circulation and a primary rainband now curls around the the northern and western sides of the center. However, there are only thin bands of showers in much of the eastern half of the circulation. With persistent thunderstorms near the core of TD2, it possess enough tropical characteristics to be considered a tropical cyclone.
An upper level low near Cuba and an upper level ridge northeast of TD2 are combining to generate northerly winds over the top of the circulation. Those winds are causing moderate vertical wind shear. TD2 will also be moving over slightly cooler Sear Surface Temperatures (SSTs) during the next 12 to 18 hours. The combination of the vertical wind shear and cooler SSTs could keep TD2 from intensifying much during that time period. TD2 will move over the warmer SSTs of the Gulf Stream later on Saturday. The vertical wind shear could also decrease somewhat. Warmer SSTs and less wind shear could allow TD2 to intensify into Tropical Storm Bonnie later on Saturday.
A ridge northeast of TD2 is steering the tropical depression toward the west-northwest and a general motion in that direction is expected for another 36 to 48 hours. After about two days the steering currents could weaken. On its anticipated track TD2/Tropical Storm Bonnie is expected to approach the coast of South Carolina on Sunday. Coastal erosion, rip currents and locally heavy rain are the primary risks. Wind damage is likely to be minimal.