The circulation in Tropical Depression 11 exhibited more organization on Monday night and the National Hurricane Center upgraded it to Tropical Storm Joaquin.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Joaquin was located at latitude 26.7°N and longitude 70.4°W which put it about 400 miles (640 km) northeast of the Central Bahamas and about 670 miles (1080 km) south-southeast of Cape Hatteras, North Carolina.  Joaquin was moving toward the southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1002 mb.

Tropical Storm Joaquin formed when an upper level low sat in place over warm Sea Surface Temperatures for a few days.  Transfers of momentum slowly increased the rotation in the lower atmosphere until a distinct center of circulation developed.  However, northwesterly winds in the upper levels created vertical wind shear that inhibited the development of the system.  Eventually, the wind shear decreased enough to allow more thunderstorms to develop near the center of circulation.  Condensation in those storms created a warm core in the middle and upper atmosphere and Joaquin began to intensify.  Now, upper level divergence is beginning to develop and the environment is becoming more favorable for intensification.

A ridge north of Joaquin is steering it slowly toward the west and that steering pattern is expected to continue for the next day or two.  An upper level trough approaching from the west is expected to turn Joaquin toward the north.  Guidance from numerical models is divergent.  Some models bring Joaquin to the Mid-Atlantic Coast while other models forecast Joaquin to move toward Long Island.  The future track of Joaquin will depend on how far west it moves before it turns northward and how strong it gets.