Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 30, NWS Houston/Galveston, TX

August 16, 2021Harris County, Texas

NWS Houston/Galveston, TX issued this flash flood warning at Aug 16, 2021, 4:48 PM CDT for Harris County, Texas. It was in force for 48 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 16, 2021, 4:48 PM CDT (21:48 UTC)
Expired
Aug 16, 2021, 5:36 PM CDT
In force
48 min
Issued by
NWS Houston/Galveston, TX
Area
Storm-based polygon
Flood severity
None

County Harris County, TX

The radar

The Houston radar (KHGX), 49 km from the middle of the area, began a volume at 21:51 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.

What was reported inside it

TimeReportWhereRemark
Aug 16, 5:00 PM CDTFLASH FLOOD1 Nw West University Pl, TXSEVERAL VEHICLES FLOODED DUE TO FLOODING.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 9.8 hours before the alert went out and 220 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 2021-08-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1386 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, Lake Charles Mun, LA at 12:00Z on 2021-08-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -6 square meters per square second.1939Sfc1 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
1386 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
812 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
-6 m²/s²
0-3 km storm-relative helicity
-4 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

266 
WGUS54 KHGX 162148
FFWHGX
TXC201-162245-
/O.NEW.KHGX.FF.W.0030.210816T2148Z-210816T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
448 PM CDT Mon Aug 16 2021

The National Weather Service in League City has issued a

* Flash Flood Warning for...
  Southwestern Harris County in southeastern Texas...

* Until 545 PM CDT.

* At 448 PM CDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  2 and 4 inches of rain have fallen across portions of the warned 
  area. Additional rainfall amounts of 2 to 4 inches may be possible 
  across portions of the the warned area. Flash flooding is ongoing 
  or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  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...
  Northwestern Pasadena, Bellaire, West University Place, Galena 
  Park, Jacinto City, Hunters Creek Village, Bunker Hill Village, 
  Piney Point Village, Memorial Park, Neartown / Montrose, Fourth 
  Ward, Greater Heights, Afton Oaks / River Oaks Area, Midtown 
  Houston, Greenway / Upper Kirby Area, Downtown Houston, University 
  Place, Near Northside Houston, Greater Third Ward and Macgregor.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2983 9563 2984 9518 2970 9519 2969 9562

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

Cady
2 follow-up statements
878 
WGUS74 KHGX 162221
FFSHGX

Flash Flood Statement
National Weather Service Houston/Galveston TX
521 PM CDT Mon Aug 16 2021

TXC201-162245-
/O.CON.KHGX.FF.W.0030.000000T0000Z-210816T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Harris TX-
521 PM CDT Mon Aug 16 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM CDT THIS 
AFTERNOON FOR SOUTHWESTERN HARRIS COUNTY...

At 521 PM CDT, Doppler radar and automated rain gauges indicated 
thunderstorms producing heavy rain across the warned area. Between 2 
and 4 inches of rain have fallen.

The heaviest rains have diminished across the area. However, there 
are widespread reports of street flooding and floodwaters may be 
slow to recede.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar and automated gauges.

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...
  Northwestern Pasadena, Bellaire, West University Place, Galena 
  Park, Jacinto City, Hunters Creek Village, Bunker Hill Village, 
  Piney Point Village, Memorial Park, Neartown / Montrose, Fourth 
  Ward, Greater Heights, Afton Oaks / River Oaks Area, Midtown 
  Houston, Greenway / Upper Kirby Area, Downtown Houston, University 
  Place, Near Northside Houston, Greater Third Ward and Macgregor.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2983 9563 2984 9518 2970 9519 2969 9562

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

Cady
882 
WGUS74 KHGX 162236
FFSHGX

Flash Flood Statement
National Weather Service Houston/Galveston TX
536 PM CDT Mon Aug 16 2021

TXC201-162246-
/O.CAN.KHGX.FF.W.0030.000000T0000Z-210816T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Harris TX-
536 PM CDT Mon Aug 16 2021

...FLASH FLOOD WARNING FOR SOUTHWESTERN HARRIS COUNTY HAS BEEN 
REPLACED WITH A FLOOD WARNING...

The heaviest rains have diminished across the area. However, there 
have been widespread reports of street flooding across the Houston 
area and floodwaters may be
slow to recede. Continue to avoid any flooded roads and exercise 
increased caution if traveling.

LAT...LON 2983 9563 2984 9518 2970 9519 2969 9562

$$

Cady

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 16, 4:23 PM CDTAreal Flood AdvisoryHGXHarris52 min
Aug 16, 4:43 PM CDTSpecial Weather StatementHGXHarris32 min
Aug 16, 5:36 PM CDTAreal Flood WarningHGXHarris84 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.