Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 33, NWS Houston/Galveston, TX

September 13, 2021Matagorda County, Texas

NWS Houston/Galveston, TX issued this flash flood warning at Sep 13, 2021, 10:31 PM CDT for Matagorda County, Texas. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Sep 13, 2021, 10:31 PM CDT (03:31 UTC)
Expired
Sep 14, 2021, 1:30 AM CDT
In force
3 hr
Issued by
NWS Houston/Galveston, TX
Area
Storm-based polygon
Flood severity
None

County Matagorda County, TX

The radar

The Houston radar (KHGX), 114 km from the middle of the area, began a volume at 03:31 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

Corpus Christi, TX (KCRP), launched 00:00Z, 3.5 hours before the alert went out and 180 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, Corpus Christi, TX at 00:00Z on 2021-09-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 36 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Corpus Christi, TX at 00:00Z on 2021-09-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -68 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
36 J/kg
Mixed-layer CIN
-242 J/kg
Mixed-layer LCL
656 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-68 m²/s²
0-3 km storm-relative helicity
-42 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

651 
WGUS54 KHGX 140331
FFWHGX
TXC321-140630-
/O.NEW.KHGX.FF.W.0033.210914T0331Z-210914T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
1031 PM CDT Mon Sep 13 2021

The National Weather Service in League City has issued a

* Flash Flood Warning for...
  Central Matagorda County in southeastern Texas...

* Until 130 AM CDT.

* At 1031 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing and 
  may worsen as additional rainfall occurs.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Matagorda and Sargent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2876 9605 2893 9568 2876 9562 2868 9575
      2858 9599 2858 9603

FLASH FLOOD...RADAR INDICATED

$$

kp

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 13, 7:32 PM CDTFlash Flood WarningHGXBrazoria, Jackson, Matagorda3 hr
Sep 13, 9:46 PM CDTFlash Flood WarningHGXBrazoria, Galveston, Matagorda4 hr
Sep 13, 10:06 PM CDTHurricane WarningHGXBrazoria, Jackson, Matagorda6 hr
Sep 14, 1:43 AM CDTFlash Flood WarningHGXBrazoria, Galveston, Harris, Matagorda4 hr
Sep 14, 3:33 AM CDTFlash Flood WarningHGXBrazoria, Chambers, Galveston, Harris4 hr
Sep 14, 3:57 AM CDTSmall Craft AdvisoryHGX18 hr
Sep 14, 4:04 AM CDTCoastal Flood AdvisoryHGXBrazoria, Chambers, Galveston, Harris, Matagorda14 hr
Sep 14, 4:42 AM CDTRiver Flood WarningHGXGalveston, Harris28 hr
Sep 14, 5:29 AM CDTRiver Flood WarningHGXGalveston, Harris21 days
Sep 14, 5:31 AM CDTRiver Flood WarningHGXGalveston, Harris21 days
Sep 14, 5:45 AM CDTFlash Flood WarningHGXBrazoria, Chambers, Galveston, Harris3 hr
Sep 14, 8:11 AM CDTAreal Flood WarningHGXBrazoria, Galveston, Harris3 hr

Nearby

Flash Flood Warnings in Texas, 2021Every flash flood warning in 2021

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.