Tropical Disturbance Brings Rain to Southeastern Bahamas

A tropical disturbance brought rain to the Southeastern Bahamas on Wednesday.  The disturbance was also designated at Invest 95L.  At 8:00 p.m. EDT on Wednesday the center of the tropical disturbance was located at latitude 21.8°N and longitude 74.0°W which put it about 30 miles (50 km) southeast of Acklins Island, Bahamas.  The disturbance was moving toward the west-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1010 mb.

The circulation around the tropical disturbance was not well organized on Wednesday.  There were indications of cyclonic turning in the wind flow, but there were no reports of westerly winds at the surface.  The lack of westerly winds indicated that there probably was not a defined center of circulation at the surface.  There were some thunderstorms near the apparent middle of the tropical disturbance.  There was a larger cluster of thunderstorms east of the middle of the disturbance and a second cluster of thunderstorms northeast of the middle of the disturbance.

The tropical disturbance will be in an environment marginally favorable for the development of a tropical cyclone.  The disturbance will move over water where the Sea Surface Temperature is near 29°C.  A large upper level low over the eastern Gulf of Mexico is producing southerly winds which are blowing over the western half of the disturbance.  Those winds are producing moderate vertical wind shear.  There is another, smaller upper level low near Bermuda.  An small upper level ridge is developing between the two upper lows.  The winds are weaker in the ridge which is over the eastern half of the tropical disturbance.  It is possible that a center of circulation could develop in one of the clusters of thunderstorms east and northeast of the middle of the disturbance.  The National Hurricane Center is indicating that there is a 50% probability of development of a tropical cyclone during the next 48 hours and a 70% during the next five days.

The upper low over the Gulf of Mexico and the developing upper ridge are likely to combine to steer the disturbance toward the northwest during the next few days.  It is difficult to anticipate the  track until a distinct center of rotation forms.  If the center reforms east or northeast of the current middle of the disturbance, then that would affect the future track.  On the most probable track the disturbance would move across the southeastern and central Bahamas during the next several days.  It could approach southeast Florida or the Florida Keys on Friday night.  The disturbance could move into the eastern Gulf of Mexico during the weekend.  If the disturbance brings any significant rain to the northern Bahamas, that would hamper efforts to recover from the catastrophic damage caused by Hurricane Dorian.