[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 180236
TCDAT1

Potential Tropical Cyclone Sixteen Discussion Number   3
NWS National Hurricane Center Miami FL       AL162019
1000 PM CDT Thu Oct 17 2019

The disturbance over the southwestern Gulf of Mexico continues to
produce a large area of cloudiness and thunderstorms over much of
the central and southwestern Gulf of Mexico.  The system is not yet
a tropical or subtropical cyclone as it still lacks sufficient
convective organization and an Air Force reconnaissance aircraft
that flew into the disturbance late this afternoon found a broad
circulation, but no evidence of a well-defined center. The global
models indicate that the circulation will become better defined by
early Friday, and that the low will deepen within an area of strong
upper-level divergence to the east of an upper-level trough over
southeastern Texas.  As a result, strengthening is forecast while
the system moves over the Gulf of Mexico during the next 24 to 36
hours.  While the system is unlikely to develop into a classical
tropical cyclone, it is expected to obtain enough organized
convection to become a tropical or subtropical cyclone on Friday or
Friday night before is reaches the northern Gulf coast. 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.

The disturbance is moving northeastward at about 10 kt.  The system
should accelerate northeastward ahead of the aforementioned trough
on Friday, and the northeastward motion should then continue during
the next few days. The low is forecast to slow down and turn
east-northeastward after 72 hours when the mid-level flow becomes
more zonal.  The new NHC track forecast uses a blend of the lastest
global model fields and is very similar to the previous advisory.

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.

Key Messages:

1. There is a danger of life-threatening storm surge inundation of
up to 5 feet above ground level beginning Friday along the Florida
Gulf Coast from Indian Pass to Clearwater, where a Storm Surge
Warning is in effect. Residents in these areas should follow advice
given by local officials.

2. Tropical storm force winds are likely by Friday afternoon along
portions of the central and eastern Gulf Coast, where tropical storm
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.

3. Isolated flash flooding is possible along the central and eastern
Gulf Coast, mainly Friday and Friday night. Since soils across the
southeast are dry, the risk of flash flooding will be confined to
the immediate coast where heavier rainfall is possible.

4. 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  18/0300Z 24.1N  93.7W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  18/1200Z 26.0N  91.1W   35 KT  40 MPH...TROPICAL STORM
 24H  19/0000Z 28.2N  88.5W   45 KT  50 MPH
 36H  19/1200Z 30.2N  86.1W   45 KT  50 MPH
 48H  20/0000Z 32.2N  82.9W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  21/0000Z 36.1N  74.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  22/0000Z 37.0N  69.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  23/0000Z...DISSIPATED

$$
Forecaster Brown
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