Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 22, NWS Houston/Galveston, TX

June 21, 2021Harris County, Texas

NWS Houston/Galveston, TX issued this flash flood warning at Jun 21, 2021, 5:34 PM CDT for Harris County, Texas. It was in force for 116 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jun 21, 2021, 5:34 PM CDT (22:34 UTC)
Expired: Jun 21, 2021, 7:30 PM CDT
In force: 116 min
Issued by: NWS Houston/Galveston, TX
Area: Storm-based polygon
Flood severity: None

County Harris County, TX

The radar

The Houston radar (KHGX), 41 km from the middle of the area, began a volume at 22:33 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, 10.6 hours before the alert went out and 185 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 2694 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 647 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: -21 m²/s²
0-3 km storm-relative helicity: 182 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

246 
WGUS54 KHGX 212234
FFWHGX
TXC201-220030-
/O.NEW.KHGX.FF.W.0022.210621T2234Z-210622T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
534 PM CDT Mon Jun 21 2021

The National Weather Service in League City has issued a

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

* Until 730 PM CDT.

* At 534 PM CDT, Doppler radar indicated slow moving thunderstorms 
  producing heavy rain across the warned area. Rainfall rates of 
  2-3.5 inches per hours. So far between 1 and 3.5 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Northwestern Baytown, Barrett, Highlands, Channelview, Cloverleaf, 
  Crosby, Sheldon, northern Houston Ship Channel and Lake Houston.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Excessive runoff from heavy rainfall will cause flooding of small 
creeks and streams, urban areas, highways, streets and underpasses 
as well as other drainage areas and low lying spots.

&&

LAT...LON 2976 9515 2979 9518 2982 9519 2985 9521
      2991 9517 2990 9514 2991 9508 2994 9505
      2994 9501 2992 9500 2989 9500 2987 9501
      2978 9500 2978 9504 2979 9507 2979 9508
      2980 9509 2978 9513

FLASH FLOOD...RADAR INDICATED

$$

kp

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 7:37 PM CDT	Special Marine Warning	HGX		53 min
Jun 20, 9:22 PM CDT	Special Marine Warning	HGX		38 min
Jun 21, 1:08 AM CDT	Special Marine Warning	HGX		67 min
Jun 21, 3:46 AM CDT	Rip Current Statement	HGX	Brazoria, Galveston, Matagorda	15 hr
Jun 21, 4:37 PM CDT	Special Weather Statement	HGX	Liberty	38 min
Jun 21, 4:58 PM CDT	Areal Flood Advisory	HGX	Harris	3 hr
Jun 21, 5:07 PM CDT	Special Weather Statement	HGX	Harris	38 min
Jun 21, 5:42 PM CDT	Special Weather Statement	HGX	Harris	48 min
Jun 21, 5:49 PM CDT	Areal Flood Advisory	HGX	Chambers, Harris, Liberty, Montgomery	116 min
Jun 21, 5:59 PM CDT	Areal Flood Advisory	HGX	Austin, Waller, Washington	2 hr
Jun 21, 6:51 PM CDT	Flash Flood Warning	HGX	Harris	114 min

Nearby

Flash Flood Warnings in Texas, 2021 Every 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.