[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 252059
TCDAT3

Hurricane Hanna Discussion Number  12
NWS National Hurricane Center Miami FL       AL082020
400 PM CDT Sat Jul 25 2020

NOAA Doppler weather radar data from Brownsville and Corpus Christi,
Texas, along with reconnaissance data from the Air Force Hurricane
Hunters indicate that Hanna has continued to strengthen this
afternoon. A 30-nmi-wide eye remains distinct in the radar data, and
dropsonde and 700-mb flight-level-level height data from the
aircraft indicate that the central pressure has decreased to 973 mb.
The aircraft measured a peak 700-mb flight-level wind speed of 86 kt
on its last outbound leg, which equates to about 77 kt at the
surface. Coincident with the flight-level wind data were SFMR
surface wind speeds of 80 kt. In addition, Doppler velocity values
have been averaging close to 100 kt between 5000-6000 ft in the
northern and northeastern eyewall, which converts to 80-kt surface
wind speed estimates. Based on these data, the initial intensity has
been increased to 80 kt. No further strengthening is anticipated
before the center of Hanna's eye makes landfall along the south
Texas coast in a few hours.

Doppler radar and aircraft reconnaissance fixes indicate that Hanna
has finally made the much anticipated turn toward the
west-southwest, now showing an initial motion of 255/07 kt. A
west-southwestward motion is expected to continue for the next 48
hours, which will take Hanna well inland over south Texas, followed
by eventual dissipation in about 48 h over over the mountains of
northeastern Mexico. The new NHC track forecast remains unchanged
from the previous advisory, and lies near the center of the tightly
packed consensus models.


Key Messages

1. Life-threatening storm surge will continue along portions of 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 will continue within the Hurricane Warning
area along the Texas coast through this evening. Strong winds will
also spread inland across portions of South Texas where Tropical
Storm and Hurricane Warnings are in effect.

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


FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 26.8N  97.2W   80 KT  90 MPH
 12H  26/0600Z 26.7N  98.4W   50 KT  60 MPH...INLAND
 24H  26/1800Z 26.0N 100.0W   30 KT  35 MPH...INLAND
 36H  27/0600Z 25.5N 101.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  27/1800Z...DISSIPATED INLAND

$$
Forecaster Stewart
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