Tropical Weather Update – September 13, 2019

Potential Tropical Cyclone Nine Discussion Number 4

NWS National Hurricane Center Miami FL AL092019

1100 AM EDT Fri Sep 13 2019

Preliminary data from a reconnaissance plane indicate that the

disturbance has not developed a well-defined center yet and

continues to be characterized by an elongated SW to NE trough of low

pressure. Satellite images however, suggest that the system could

be consolidating a little bit farther to the east within the area of

deep convection. The reconnaissance plane will also check this

region soon. In this advisory, the initial position is a point near

the middle of of the trough, but not quite as far east as the

convective area. The initial intensity remains 25 kt.

The disturbance is embedded within a moderate shear environment, but

this parameter is not expected to be strong enough to halt

development. The NHC forecast still calls for this system to

become a tropical cyclone later today or Saturday. Global models

develop the system and guidance suggests that the cyclone could even

reach hurricane intensity by the end of the forecast period. By

then, the system is expected to be over the Atlantic well southeast

of the coast of the Carolinas.

Due to a lack of a well-defined center, the initial motion is highly

uncertain. It appears that there has been little motion during

the past few hours. A weakness in the ridge over the western

Atlantic is forecast to develop and this pattern should steer the

system slowly toward the northwest and then northward. In about 3

days, an eastward moving mid-latitude trough will force the system

to recurve away from the coast toward the Atlantic. The guidance

has shifted a little to east this morning and consequently the NHC

track forecast was adjusted in that direction. However, the official

forecast is still on the western edge of the guidance envelope. If

the disturbance develops a little more to the east, the track

forecast will probably adjusted to the right later tod