Potential Tropical Cyclone Sixteen Discussion Number 4
NWS National Hurricane Center Miami FL AL162019
400 AM CDT Fri Oct 18 2019
Although the convection associated with the disturbance has
increased during the past few hours, there is no evidence that a
well-defined center has formed yet. One can observe several swirls
of low clouds rotating within a larger gyre. Most of the global
models forecast that the system will become better organized
later today, and given the current trend, NHC forecasts that a
tropical or most likely a subtropical cyclone will form later this
morning. A reconnaissance plane will investigate the disturbance in
a few hours.
The disturbance is located to the east of an upper trough which
is digging along the western Gulf of Mexico, and the upper-level
diffluence caused by the trough should induce some strengthening
during the next 24 hours or so before the system moves inland.
However, the simulated convection by the GFS and the ECMWF models
resembles a comma-shape pattern which is characteristic of a
subtropical cyclone. After landfall, the cyclone is expected to
become extratropical and gradually weaken while it moves
northeastward near the southeast U.S. coast. By day 5, the low is
forecast to be absorbed by a front over the western Atlantic.
Since the center is not well defined, the initial motion is highly
uncertain. The best estimate is toward the northeast or 045 degrees
at 12 kt. The system should accelerate later today and continue
toward the northeast embedded within the flow ahead of the trough.
Track models are in remarkably good agreement, and the NHC
forecast is in the middle of the tight guidance envelope.
Regardless of the exact evolution of the system, portions of the
northern coast of the Gulf of Mexico will experience strong winds,
locally heavy rains, and storm surge Friday and Saturday. Similar
impacts are expected across portions of the Atlantic coast of the
southeastern United States Saturday and Sunday.