[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 250249
TCDAT3

Tropical Storm Hanna Discussion Number   9
NWS National Hurricane Center Miami FL       AL082020
1000 PM CDT Fri Jul 24 2020

Hanna continues to strengthen over the northwestern Gulf of Mexico.
Satellite and Doppler radar images indicate that the inner core
continues to become better organized and the outer bands are now
more symmetrical around the center.  The NOAA Hurricane Hunters are
currently investigating Hanna and have found maximum 850 mb
flight-level winds of 72 kt and maximum SFMR winds of 51 kt.  Based
on this data, the initial intensity is increased to 55 kt for this
advisory.  The aircraft has also reported a minimum pressure of 992
mb, which is a 8 mb drop from the flight earlier today.

The NOAA aircraft data indicate that the center has moved a little
south of west during the past few hours, and the storm is now a
little south of the previous forecast track.  A strengthening
subtropical ridge over the central U.S. should cause the storm to
continue to move generally westward, taking the center across the
southern Texas coast tomorrow afternoon or early evening.  After
landfall, the storm is expected to turn to the west-southwest or
southwest across extreme southern Texas and northern Mexico, and
that motion should continue until the system dissipates.

Hanna still has another 18 hours or so to strengthen as it remains
in light wind shear conditions and over the warm Gulf of Mexico
waters.  Since the structure of the system continues to improve, it
seems likely that Hanna will reach hurricane intensity before it
makes landfall.  The peak intensity could be higher than what is
shown in the intensity forecast below since landfall is expected
to occur between the 12 and 24 h forecast times. After landfall,
rapid weakening is anticipated, and Hanna is expected to dissipate
on Monday over the rugged terrain of northern Mexico.  The NHC
intensity forecast lies at the high end of the model guidance for
the next 24 h.

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
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 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  25/0300Z 27.1N  94.8W   55 KT  65 MPH
 12H  25/1200Z 27.1N  96.1W   65 KT  75 MPH
 24H  26/0000Z 27.0N  97.7W   60 KT  70 MPH...INLAND
 36H  26/1200Z 26.6N  99.3W   35 KT  40 MPH...INLAND
 48H  27/0000Z 25.9N 101.0W   25 KT  30 MPH...INLAND
 60H  27/1200Z 25.2N 102.4W   20 KT  25 MPH...POST-TROP/INLAND
 72H  28/0000Z...DISSIPATED

$$
Forecaster Cangialosi
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