[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 070235
TCDAT4

Potential Tropical Cyclone Fourteen Discussion Number   2
NWS National Hurricane Center Miami FL       AL142018
1000 PM CDT Sat Oct 06 2018

The cloud pattern has improved in organization and surface pressures
are gradually falling, but there is no evidence that the system is
a tropical cyclone at this time.  All indications are, however, that
a tropical depression will likely form at any time soon. Strong wind
shear is expected to affect the disturbance, and the SHIPS model
only show a modest strengthening. This is in contrast to some global
models and the HWRF, which are more aggressive in developing this
system.  Since the environment is marginally favorable, the NHC
forecast only gradually strengthens the system at the rate of the
intensity consensus IVCN.  However, the forecast is highly uncertain
given the solution of the global models.

Since the system does not have a well-defined center, the initial
motion is also uncertain. The best estimate is toward the north or
360 degrees at 6 kt. Over the next 2 or 3 days, the cyclone will be
embedded within the deep southerly flow between a strong subtropical
ridge over the western Atlantic and a sharp mid-latitude trough
advancing eastward over the United States.  This flow pattern will
force the system to move northward at 5 to 10 kt across the
eastern Gulf of Mexico for the next 2 to 3 days. By day 4, the
system should have moved inland and be weakening. It should
then race northeastward farther inland across the eastern U.S.  The
track guidance envelope is remarkably quite tight. This increases
the confidence in the track forecast primarily after the cyclone
forms.

Key Messages for Potential Tropical Cyclone Fourteen:

1.  This system is producing heavy rainfall and flash flooding over
portions of Central America, and these rains will spread over
western Cuba and the northeastern Yucatan Peninsula of Mexico during
the next couple of days.

2.  The system is forecast to become a tropical storm by late
Sunday, and tropical storm conditions are expected over portions of
western Cuba, where a Tropical Storm Warning is in effect.

3.  The system could bring storm surge, rainfall, and wind impacts
to portions of the northern Gulf Coast by mid-week, although it is
too soon to specify the exact location and magnitude of these
impacts.  Residents in these areas should monitor the progress of
this system.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 18.8N  86.6W   25 KT  30 MPH...POTENTIAL TROP CYCLONE
 12H  07/1200Z 19.5N  86.5W   30 KT  35 MPH...TROPICAL CYCLONE
 24H  08/0000Z 21.0N  86.2W   35 KT  40 MPH
 36H  08/1200Z 22.3N  86.1W   40 KT  45 MPH
 48H  09/0000Z 23.8N  86.3W   45 KT  50 MPH
 72H  10/0000Z 27.4N  87.2W   55 KT  65 MPH
 96H  11/0000Z 32.0N  85.0W   30 KT  35 MPH...INLAND
120H  12/0000Z 38.5N  77.5W   30 KT  35 MPH...INLAND

$$
Forecaster Avila
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