[Tropical] Tropical Cyclone Discussion

EMWIN Server emwin at nashvilleweather.net
Sat Jul 25 03:37:55 CDT 2020


WTNT43 KNHC 250837
TCDAT3

Tropical Storm Hanna Discussion Number  10
NWS National Hurricane Center Miami FL       AL082020
400 AM CDT Sat Jul 25 2020

Hanna continues to become better organized on satellite images,
with an extensive area of cold cloud tops in both its Central Dense
Overcast and in banding features over the eastern and southern
parts of the circulation.  Dvorak intensity estimates from TAFB and
SAB are at 55 kt, but with the continued increase in organization
over the past couple of hours, the current intensity is set at 60
kt.  This is also in agreement with the latest objective Dvorak
estimate from UW-CIMSS.  A NOAA Hurricane Hunter aircraft is
scheduled to investigate Hanna later this morning which should
provide a more precise intensity estimate.  Since Hanna should
remain in an atmospheric and oceanic environment that is conducive
for strengthening up to landfall, the cyclone should become a
hurricane very soon.  The NHC intensity forecast is close to the
model consensus.

The center is moving just slightly south of due west or around
265/8 kt.  A mid-level subtropical high to the north of Hanna has
built a little and this should result in a turn toward the
west-southwest during the next 12-24 hours.  After landfall, the
track guidance shows a continued west-southwestward motion until
dissipation over the mountainous terrain of northeastern Mexico.
The official track forecast has been adjusted just a bit to the
south of the previous forecast.  This is just north of the
dynamical model consensus and just south of the latest ECMWF
track.

Based on the new official forecast track, the Storm Surge Warning
has been extended southward to Port Mansfield, Texas.


Key Messages

1. There is a danger of life-threatening storm surge along the Texas
coast from Port Mansfield 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
Port Mansfield to Mesquite Bay, where a Hurricane Warning is in
effect.  Tropical storm conditions are expected to first reach the
coast within the warning area this 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  25/0900Z 27.0N  95.8W   60 KT  70 MPH
 12H  25/1800Z 26.9N  97.1W   70 KT  80 MPH
 24H  26/0600Z 26.5N  98.5W   50 KT  60 MPH...INLAND
 36H  26/1800Z 26.0N 100.0W   30 KT  35 MPH...INLAND
 48H  27/0600Z 25.5N 101.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  27/1800Z...DISSIPATED

$$
Forecaster Pasch
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