Flash Flood Warning 23, NWS Houston/Galveston, TX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1235 AM CDT Tue Sep 22 2020

...Very Dangerous Flash Flood Threat Developing Tonight...

Tropical Storm Beta's feeder bands containing showers and possible embedded
thunderstorms will continue to develop and spread across parts of Southeast
Texas overnight. Lots of models are showing a lot more rain possibly
moving across the same areas that received very heavy rainfall Monday
evening and produced flash flooding. Many locations stretching from
southern Harris County into the northern parts of Brazoria County and
Galveston County have already received 5 to almost 8 inches of rain.
If the overnight through early morning feeder bands develop and train
across these same areas...a very dangerous flash flooding event will
occur with another round of 5 to up to 10 inches of rain possible.

Remember...Turn around, don't drown when encountering flooded roads.
Most flood deaths occur in vehicles.

Be especially cautious overnight when it is harder to recognize the
dangers of flooding.

42/43/11/24

&&

.AVIATION...

06Z TAFS will be dealing with MVFR/IFR conditions overnight and possibly
throughout much of the day tomorrow as periods of SHRA and possible
TSRA related to the outer bands of Tropical Storm Beta move across
the area. Rains could be heavy at times and winds could be gusty at
times.  42

&&

.PREV DISCUSSION... /ISSUED 720 PM CDT Mon Sep 21 2020/

SHORT TERM [Through Wednesday Night]...

Tropical Storm Beta is still slowly moving its way to the SETX
coast. Sitting just outside the Matagorda Bay area, landfall is
expected tonight still. Rain fall is still expected to continue
through the evening and into the night. Winds are decreasing in
speed and expected to decrease under tropical storm force tomorrow
night as the system moves along the coastline near the
Matagorda/Angleton Co area. Rain bands will become more wide spread
across the SETX area as the storm loses strength and organization
throughout tonight and the day tomorrow. Tomorrow night and through
Wednesday morning, the system is expected to be moving out of the
area. Chances will be decreasing across the CWA through Thursday
early morning. Winds are going to be on the decline tonight with
winds at or under tropical storm force along the southern coastal
counties. By wednesday night and into Thursday early morning, winds
will have decreased to northerly around 10mph. 35

LONG TERM [Thursday through Monday]...

While the remnants of Beta are expected to be well E/NE of the CWA
by Thurs, some isolated/widely scattered rain chances could linger
over parts of SE TX through the end of the week. A broad mid/upper
level trof axis is progged to develop across the state (stretching
from the lower Rio Grande Valley E/NE towards SE TX) could provide
enough instability to produce some activity across this area. How-
ever, moisture levels should be rather limited in the wake of Beta
and will keep our "best" POPs over the eastern CWA. These low POPs
could persist into Fri/Sat as light onshore winds resume...and may
be helped along by the seabreeze.

While previous model runs were more aggressive with the idea of a
cold front moving down into the region on Sun, 12Z runs appear to
be backing off a little bit. A rather amplified upper ridge build-
ing in over the western U.S. seems to be shunting the bulk of the
colder air more east of the region initially(Sun) but a deepening
upper low tracking over the Northern Plains could be advantageous
in driving a second stronger cold front into SE TX by next Tues.
Time will tell. 41

MARINE...

With Tropical Storm Beta continuing to slowly make its way towards
the Central TX coast, conditions will remain poor across our bays/
coastal waters tonight into tomorrow morning. The latest TPC track
has Beta moving along/just off the Upper TX coast through tomorrow
as it weakens to a remnant low. The southerly flow on the backside
of this storm system (mainly our offshore waters tonight/tomorrow)
will be shifting to the N/NW by Weds as it moves northeasterly out
of the region. Tropical storm conditions are expected to "improve"
to Small Craft Advisory conditions early late Tue night/early Weds
morning...with most flags likely gone by Weds night. Thereafter, a
generally light/moderate offshore flow should prevail for the rest
of the week. Light onshore winds are set to resume by late Fri and
Sat. A weak cold front is possible Sun, but models are now hinting
that a second stronger front could push off the coast by next Tues.
41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      67  78  65  82  65 /  70  50  10  10   0
Houston (IAH)              71  81  70  84  70 /  80  60  20  20  10
Galveston (GLS)            76  84  74  84  74 /  70  70  40  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Tropical Storm Warning for the following zones: Brazoria
     Islands...Chambers...Coastal Brazoria...Coastal Galveston...
     Coastal Harris...Coastal Jackson...Coastal Matagorda...
     Galveston Island and Bolivar Peninsula...Inland Brazoria...
     Inland Galveston...Inland Jackson...Inland Matagorda...
     Matagorda Islands...Southern Liberty...Wharton.

     Storm Surge Warning for the following zones: Brazoria Islands...
     Chambers...Coastal Brazoria...Coastal Galveston...Coastal
     Harris...Coastal Jackson...Coastal Matagorda...Galveston
     Island and Bolivar Peninsula...Matagorda Islands.

     Flash Flood Watch through Wednesday morning for the following
     zones: Austin...Brazoria Islands...Chambers...Coastal
     Brazoria...Coastal Galveston...Coastal Harris...Coastal
     Jackson...Coastal Matagorda...Colorado...Fort Bend...
     Galveston Island and Bolivar Peninsula...Inland Brazoria...
     Inland Galveston...Inland Harris...Inland Jackson...Inland
     Matagorda...Matagorda Islands...Montgomery...Northern
     Liberty...Southern Liberty...Waller...Wharton.

GM...Tropical Storm Warning for the following zones: Coastal waters
     from Freeport to Matagorda Ship Channel TX out 20 NM...
     Coastal waters from High Island to Freeport TX out 20 NM...
     Galveston Bay...Matagorda Bay...Waters from Freeport to
     Matagorda Ship Channel TX from 20 to 60 NM...Waters from
     High Island to Freeport TX from 20 to 60 NM.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
907 PM CDT MON SEP 21 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0814 PM     FLASH FLOOD      2 ENE BROOKSIDE VILLAGE 29.60N 95.29W
09/21/2020                   HARRIS             TX   FIRE DEPT/RESCUE

            FIRE DEPARTMENT RESPONDING FOR WATER RESCUE
            NEAR THE INTERSECTION OF S SAM HOUSTON AND
            TELEPHONE RD.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1023 PM CDT MON SEP 21 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0941 PM     TROPICAL STORM   18 ESE PALACIOS         28.59N 95.98W
09/21/2020                   GMZ350             TX   MESONET

            WIND GUST WAS MEASURED AT THE MATAGORDA BAY
            WEATHERFLOW SITE XMGB.

&&