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Potential Tropical Cyclone Sixteen Discussion Number   1
NWS National Hurricane Center Miami FL       AL162019
1000 AM CDT Thu Oct 17 2019

A complicated weather situation is evolving in the Gulf of Mexico.
The circulation associated with the tropical disturbance over the
southwestern Gulf of Mexico is getting better defined, and the
associated convection is getting better organized.  However, a
strong mid- to upper-level trough is moving eastward across
southern Texas and northern Mexico, and a frontal system is present
over the northern and northwestern Gulf of Mexico.  The ECMWF and
GFS models suggest that the trough will spawn a low along the
front, with the tropical disturbance merging with that low.  On the
other hand, the UKMET suggests the tropical disturbance will become
the primary low pressure system.  Either way, it is likely that a
low pressure area with gale-force winds and at least some tropical
cyclone characteristics will move northeastward and affect
portions of the northern Gulf coast during the next 36-48 h.  Based
on this, advisories are initiated on Potential Tropical cyclone
Sixteen, and coastal tropical cyclone and storm surge
watches/warnings are being issued.

The system should track generally northeastward in the southern
portion of the mid-latitude westerlies, and the track model
guidance is in reasonably good agreement through 96 h.  The forecast
track lies a little to the south of the model consensus, as the
UKMET has a somewhat more southerly track.  The forecast track
brings the system across the southeastern United States between
48-72 h, and then has it moving into the Atlantic east of the
mid-Atlantic States.

Gradual strengthening is expected as strong upper-level
divergence caused by the trough partly prevails over strong
vertical shear.  Thus, the intensity forecast calls for gradual
strengthening along the lines of that in the global models. It is
unlikely, though, that the system will develop into a classical
tropical cyclone.  The system is expected to be fully extratropical
by 48 h, with gradual weakening expected after that time.

Regardless of the exact evolution of this weather 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.


KEY MESSAGES:

1. Dangerous storm surge inundation of up to 5 feet above ground
level is possible along the Florida Gulf Coast from Indian Pass to
Clearwater, where a Storm Surge Watch is in effect. Residents in
these areas should follow advice given by local officials.

2. Tropical storm force winds are likely along portions of the
north-central and northeastern Gulf Coast where tropical storm
watches and warnings are in effect. Regardless of the exact track
and intensity of the system, these winds will cover a large area,
especially east of the center, and begin well in advance of the
arrival of the center.

3. Wind and coastal flooding hazards along the U.S. East Coast will
be covered by non-tropical watches and warnings issued by local NWS
offices, since the system is expected to lose any tropical
characteristics after it moves inland along the Gulf Coast.


FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 22.4N  95.7W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  18/0000Z 23.7N  94.2W   35 KT  40 MPH...TROPICAL STORM
 24H  18/1200Z 25.8N  91.0W   40 KT  45 MPH
 36H  19/0000Z 28.5N  88.0W   45 KT  50 MPH
 48H  19/1200Z 30.9N  85.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  20/1200Z 35.5N  77.2W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  21/1200Z 37.5N  70.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  22/1200Z 38.0N  66.5W   25 KT  30 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven

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