Tropical Storm Joaquin is on the verge of reaching hurricane intensity. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Joaquin was located at latitude 25.8°N and longitude 71.7°W which put it about 360 miles (580 km) east of the Northwestern Bahamas and about 680 miles (1100 km) south-southeast of Cape Hatteras, North Carolina. Joaquin was moving toward the west-southwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 988 mb. The government of the Bahamas has issued a Hurricane Watch for the Central Bahamas.
The organization of the circulation of Tropical Storm Joaquin increased on Tuesday in spite of moderate amounts of vertical wind shear. More thunderstorms developed near the core of circulation and a partial eyewall formed around the southern and eastern parts of the center. Although it is more organized, the circulation is still asymmetrical and the stronger winds were found in the eastern side of the tropical storm.
A thin upper level ridge is east of Florida and clockwise flow around the ridge is producing northerly winds over the top of Joaquin. Those winds produced moderate vertical wind shear on Tuesday but the shear appears to be decreasing with time. Joaquin is over water where the Sea Surface Temperature is near 30°C. As the upper level winds diminish, the environment favors intensification and Joaquin is likely to become a hurricane on Wednesday. Joaquin will continue to be in an environment that favors intensification during the next several days.
A ridge of high pressure north of Joaquin is blocking it from moving north and the ridge is forcing the tropical storm to move toward the west-southwest. That general motion is expected to continue for another 24 to 48 hours and it could bring Joaquin near the Central and Northwestern Bahamas. When Joaquin reaches the western end of the ridge it will turn toward the north. An upper level trough over the eastern U.S. will cause Joaquin to move more quickly toward the north at the end of the week. On its anticipated track, Joaquin could be approaching the Mid-Atlantic Coast of the U.S. by the weekend.