Alert archive / Texas / Flash Flood Watches in 2018

Flash Flood Watch 9, NWS Houston/Galveston, TX

September 12, 20189 counties in Texas

NWS Houston/Galveston, TX issued this flash flood watch at Sep 12, 2018, 3:06 PM CDT for 9 counties in Texas. It took effect at Sep 13, 2018, 12:00 AM CDT. It was in force for 52 hr.

The area

The counties it named.

The facts

Issued
Sep 12, 2018, 3:06 PM CDT (20:06 UTC)
In effect from
Sep 13, 2018, 12:00 AM CDT
Expired
Sep 15, 2018, 4:00 AM CDT
In force
52 hr
Issued by
NWS Houston/Galveston, TX
Flood severity
None

Counties Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Harris County, TX, Jackson County, TX, Liberty County, TX, Matagorda County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 43 km from the middle of the area, began a volume at 20:09 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 8.1 hours before the alert went out and 237 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Lake Charles Mun, LA at 12:00Z on 2018-09-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 711 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lake Charles Mun, LA at 12:00Z on 2018-09-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
711 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
748 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
29 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Houston/Galveston, TX wrote its last area forecast discussion before this flash flood watch went out at Sep 12, 12:34 PM CDT, 2 hours 32 minutes earlier.

Area forecast discussion, Sep 12, 12:34 PM CDT, 2 hours 32 minutes before
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Hazardous weather outlook, Sep 12, 3:39 AM CDT, 11 hours 27 minutes before
Hazardous Weather Outlook
National Weather Service Houston/Galveston TX
339 AM CDT Wed Sep 12 2018

TXZ163-164-176>179-195>200-210>214-226-227-235>238-300-313-
335>338-436>438-131200-
Austin-Brazoria Islands-Brazos-Burleson-Chambers-Coastal Brazoria-
Coastal Galveston-Coastal Harris-Coastal Jackson-
Coastal Matagorda-Colorado-Fort Bend-
Galveston Island and Bolivar Peninsula-Grimes-Houston-
Inland Brazoria-Inland Galveston-Inland Harris-Inland Jackson-
Inland Matagorda-Madison-Matagorda Islands-Montgomery-
Northern Liberty-Polk-San Jacinto-Southern Liberty-Trinity-Walker-
Waller-Washington-Wharton-
339 AM CDT Wed Sep 12 2018

This hazardous weather outlook is for portions of Southeast Texas.

.DAY ONE...Today and Tonight

Scattered to numerous showers and thunderstorms are possible,
especially close to the coast. Locally heavy rainfall is possible,
and flooding could develop if the heaviest rains fall over already
saturated grounds.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Scattered to numerous showers and thunderstorms will remain possible
through Saturday as a tropical disturbance moves inland along the
Texas coast. Locally heavy rainfall is possible, and flooding could
develop if the heaviest rains fall over already saturated grounds.

.SPOTTER INFORMATION STATEMENT...
Spotters activation might be needed.

GMZ330-335-350-355-370-375-131200-
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-
339 AM CDT Wed Sep 12 2018

This hazardous weather outlook is for portions of Southeast Texas.

.DAY ONE...Today and Tonight

Expect increasing winds and building seas. Higher winds and seas
as well as reduced visibilities in heavy rains can be expected in
any strong shower or thunderstorm activity.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

As a tropical disturbance progresses toward the Texas coast through
the end of the week, expect strengthening winds along with building
seas and swells. Mariners are urged to keep up with the latest
forecasts, as they will be subject to significant changes and
dependent on the eventual evolution of this system.

.SPOTTER INFORMATION STATEMENT...
Spotters activation might be needed.

The office that day

Everything else NWS Houston/Galveston, TX issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 12, 6:03 AM CDTAreal Flood AdvisoryHGXGalveston, Harris117 min
Sep 12, 6:27 AM CDTFlash Flood WarningHGXGalveston, Harris2 hr
Sep 12, 7:30 AM CDTAreal Flood AdvisoryHGXHarris60 min
Sep 12, 8:29 AM CDTFlash Flood WarningHGXGalveston, Harris3 hr

Nearby

Flash Flood Watches in Texas, 2018Every flash flood watch in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.