Show Selection:
Show plain - Location:
#1018385 (Received by flhurricane at: 11:09 AM 22.Sep.2020)
TCDAT2

Tropical Depression Beta Discussion Number 20
NWS National Hurricane Center Miami FL AL222020
1000 AM CDT Tue Sep 22 2020

High-resolution visible satellite imagery, surface observations, and
NOAA Doppler weather radar data from San Antonio, Corpus Christi,
and Houston, Texas, indicate that Beta has moved a little farther
inland and has weakened to a tropical depression. The same data
also show that Beta has started a slow drift toward the northeast.
Deep convection has waned considerably since the previous
advisory, especially during the past few hours, with cloud tops now
warmer than -30 deg C, which no longer meets the Dvorak satellite
classification criterion. The initial intensity is 30 kt is based
on average Doppler velocities of 35-40 kt between 1500-2500 ft ASL
just to the southeast and south of Galveston.

The initial motion estimate is now 045/02 kt. Steering currents
around Beta remain weak. However, water vapor imagery indicates that
a broad mid- to upper-level trough over western Texas is moving
slowly eastward, and that feature should gradually force Beta
east-northeastward later today and tonight, followed by a faster
motion toward the northeast on Wednesday and Thursday across
Louisiana and Mississippi before dissipating in about 4 days. The
new NHC forecast track is similar to the previous advisory track,
which keeps Beta just inland from the Gulf coast, and lies near a
blend of the simple consensus models TVCA and GFEX, and the NOAA
corrected-consensus model HCCA.

Since Beta`s center is forecast to remain just inland for the next
36-48 hours, chances of the cyclone regaining tropical storm status
are becoming less likely. As a result, the new official intensity
forecast shows Beta remaining a 25-30 kt depression during that
time, followed by weakening to a remnant low by 48 hours, and
dissipation over Mississippi or Alabama by 96 hours. This is
consistent with the various simple and corrected-consensus models.

Although Beta is now an inland tropical depression, the National
Hurricane Center will continue to issue advisories on the cyclone
due to its proximity to the Gulf of Mexico and until it becomes
clear that re-strengthening into a tropical storm is unlikely.

Key Messages:

1. Significant flash and urban flooding is occurring and will
continue for the middle and upper Texas coast today. The slow motion
of Beta will continue to produce a long duration rainfall event from
the middle Texas coast to southern Louisiana. Flash, urban, and
minor to isolated moderate river flooding is likely. Periods of
rainfall will spread east into the Lower Mississippi Valley and
portions of the Southeast through the end of the week. Flash, urban,
and isolated minor river flooding is possible on smaller rivers.

2. Persistent onshore flow will continue to result in above normal
high tides, and coastal flooding over the next few days will be slow
to recede. For information on the ongoing coastal flooding, please
refer to coastal flood products issued by local National Weather
Service offices.


FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 28.9N 96.7W 30 KT 35 MPH...INLAND
12H 23/0000Z 29.0N 96.3W 30 KT 35 MPH...INLAND
24H 23/1200Z 29.6N 95.1W 30 KT 35 MPH...INLAND
36H 24/0000Z 30.4N 93.7W 25 KT 30 MPH...INLAND
48H 24/1200Z 31.7N 92.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 25/0000Z 33.1N 90.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 25/1200Z 34.4N 88.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 26/1200Z...DISSIPATED INLAND

$$
Forecaster Stewart