[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 260853
TCDAT3

Tropical Storm Hanna Discussion Number  14
NWS National Hurricane Center Miami FL       AL082020
400 AM CDT Sun Jul 26 2020

Hanna continues to weaken as the center crosses the Rio Grande
River from Texas into northeastern Mexico.  Satellite imagery shows
some warming of the cloud tops near the center, and WSR-88D radar
data shows that only about a third of the previous eyewall is still
present to the southeast of the center.  The storm is generating a
vigorous outer convective band over the eastern semicircle.  The
initial intensity is reduced to 50 kt based mainly on Doppler radar
winds of 50-65 kt at about 9000 ft to the northeast of the center,
and it is possible that this is generous.

The initial motion remains west-southwestward or 250/8 kt.  The
mid-level ridge over the central United States should continue to
steer Hanna west-southwestward until dissipation, and the new NHC
forecast track is little changed from the previous forecast.

Hanna should rapidly weaken as it moves over northeastern Mexico,
with the system expected to weaken to a depression in 12-18 h, if
not sooner.  The system is expected to dissipate completely over the
rugged terrain of Mexico between 36-48 h.

The radar signature of the storm has weakened to the point where
there will be no more hourly position updates between advisories.

Key Messages

1. Tropical storm conditions are expected to persist for several
more hours near the center of Hanna, and for a few more hours in
the warning area along the coast of Texas and northeastern Mexico.

2. 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.

3. Storm surge along the Texas coast should diminish today.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 26.3N  98.9W   50 KT  60 MPH...INLAND
 12H  26/1800Z 25.8N  99.9W   35 KT  40 MPH...INLAND
 24H  27/0600Z 25.1N 101.4W   25 KT  30 MPH...INLAND
 36H  27/1800Z 24.5N 102.7W   20 KT  25 MPH...POST-TROP/INLAND
 48H  28/0600Z...DISSIPATED

$$
Forecaster Beven
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