[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 240834
TCDAT3

Tropical Storm Hanna Discussion Number   6
NWS National Hurricane Center Miami FL       AL082020
400 AM CDT Fri Jul 24 2020

Satellite imagery shows well-defined convective banding features
over the eastern and southern portions of the circulation with some
cooling of the cloud tops.  This suggests that the associated
thunderstorm activity is becoming more vigorous.  However, surface
observations over the Gulf and a scatterometer pass from a few
hours ago indicate that the system has not strengthened further at
this time.  The current intensity estimate is held at 35 kt in
agreement with a Dvorak classification from TAFB.  A NOAA Hurricane
Hunter aircraft is scheduled to investigate the storm later this
morning and they should provide a good estimate of Hanna's
intensity.  The storm has an impressive upper-level anticyclonic
outflow structure and should remain in a low shear environment
until it reaches the coast.  Therefore strengthening is likely
prior to landfall and the NHC intensity forecast is near the model
high end of the intensity model suite.

The storm has moved a little faster toward the west-northwest over
the past several hours, and the initial motion estimate is 290/8
kt.  There is very little change to the official track forecast or
reasoning from the previous cycle.  A gradual turn toward the west
is likely in 12 hours or so as a mid-level ridge to the north of
Hanna builds a bit.  The forecast track takes the center inland
over Texas within the tropical storm warning area on Saturday.
This is in good agreement with the dynamical model consensus and
the latest ECMWF model solution.


Key Messages

1. Hanna is forecast to strengthen and it is expected to
bring tropical-storm-force winds to portions of the Texas coast,
where a tropical storm warning is in effect.

2. Hanna is expected to produce heavy rains across portions of
southern Texas.  These rains could result in flash flooding and
isolated minor to moderate river flooding.


FORECAST POSITIONS AND MAX WINDS

INIT  24/0900Z 26.7N  92.4W   35 KT  40 MPH
 12H  24/1800Z 27.1N  93.7W   40 KT  45 MPH
 24H  25/0600Z 27.3N  95.5W   50 KT  60 MPH
 36H  25/1800Z 27.3N  97.1W   55 KT  65 MPH
 48H  26/0600Z 27.2N  98.6W   40 KT  45 MPH...INLAND
 60H  26/1800Z 26.5N 100.0W   30 KT  35 MPH...INLAND
 72H  27/0600Z 26.0N 101.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  28/0600Z...DISSIPATED

$$
Forecaster Pasch
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