[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 242059
TCDAT3

Tropical Storm Hanna Discussion Number   8
NWS National Hurricane Center Miami FL       AL082020
400 PM CDT Fri Jul 24 2020

Satellite imagery, along with Doppler radar data from Houston and
Corpus Christi, indicate that Hanna has been getting better
organized over the past several hours. Curved banding features have
improved and a banding eye has developed in the radar data. The NOAA
reconnaissance aircraft reported SFMR winds of 43-45 kt on its last
outbound leg and a ship D5DE5 just east of the center reported an
elevated wind speed of 51 kt at 1400Z. Based on these data, along
with an estimated pressure of 999 mb from surrounding oil rigs, the
initial intensity has been conservatively increased to 45 kt.

Reconnaissance and radar fix data indicate that Hanna has turned
westward, and the motion is now 275/09 kt. Hanna is forecast to move
generally westward along the southern periphery of a deep-layer
ridge for the next 24 hours, with landfall expected along the
south-central coast of Texas within the hurricane warning area
Saturday afternoon or early evening. The new NHC forecast track is
just an extension of the previous advisory track, and lies close to
an average of the consensus models TVCN, NOAA-HCCA, and FSSE.

Given the improved internal structure noted in radar imagery, along
with SSTs of at least 30 deg C and an impressive outflow pattern,
increased frictional convergence as the cyclone moves closer to the
coast and the approaching nocturnal convective maximum should
support additional strengthening, and Hanna is now forecast
to become a hurricane prior to making landfall. The NHC forecast of
65 kt in 24 hours is between the latest HWRF model run, which
brings Hanna to 70 kt just prior to landfall, and the intensity
consensus models HCCA and IVCN, which are just below hurricane
strength.

Due to Hanna forecast to reach hurricane strength, Hurricane and
Storm Surge Warnings have been issued for portions of the Texas
coast.

Key Messages

1. There is a danger of life-threatening storm surge along the Texas
coast from Baffin Bay to Sargent, where a Storm Surge Warning is in
effect. Residents in these locations should follow advice given by
local emergency officials.

2. Hurricane conditions are expected along the Texas coast from
Baffin Bay to Mesquite Bay, where a Hurricane Warning is in effect.
Tropical storm conditions are expected to first reach the coast
within the warning area Saturday morning.

3. Hanna is expected to produce heavy rains across portions of
southern Texas and northeastern Mexico.  These rains could result in
life-threatening flash flooding and isolated minor to moderate river
flooding.

FORECAST POSITIONS AND MAX WINDS

INIT  24/2100Z 27.3N  94.3W   45 KT  50 MPH
 12H  25/0600Z 27.4N  95.6W   55 KT  65 MPH
 24H  25/1800Z 27.3N  97.2W   65 KT  75 MPH
 36H  26/0600Z 27.0N  98.6W   40 KT  45 MPH...INLAND
 48H  26/1800Z 26.6N 100.3W   25 KT  30 MPH...INLAND
 60H  27/0600Z 25.6N 102.0W   20 KT  25 MPH...INLAND
 72H  27/1800Z...DISSIPATED

$$
Forecaster Stewart
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