Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 42, NWS Houston/Galveston, TX

October 2, 2021Harris County, Texas

NWS Houston/Galveston, TX issued this flash flood warning at Oct 2, 2021, 12:21 PM CDT for Harris County, Texas. It was in force for 74 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
Oct 2, 2021, 12:21 PM CDT (17:21 UTC)
Expired
Oct 2, 2021, 1:35 PM CDT
In force
74 min
Issued by
NWS Houston/Galveston, TX
Area
Storm-based polygon
Flood severity
None

County Harris County, TX

The radar

The Houston radar (KHGX), 60 km from the middle of the area, began a volume at 17:25 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, 5.4 hours before the alert went out and 197 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 2021-10-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1519 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 2021-10-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 59 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
1519 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
558 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
59 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.8

Open this sounding in Storm Lab

The text

As transmitted.

294 
WGUS54 KHGX 021721
FFWHGX
TXC201-021915-
/O.NEW.KHGX.FF.W.0042.211002T1721Z-211002T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
1221 PM CDT Sat Oct 2 2021

The National Weather Service in League City has issued a

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

* Until 215 PM CDT.

* At 1221 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  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...
  Humble, Kingwood, northwestern Atascocita, Lake Houston and 
  southeastern Bush Intercontinental Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 2999 9528 3007 9520 3001 9517 2991 9528

FLASH FLOOD...RADAR INDICATED

$$
1 follow-up statement
040 
WGUS74 KHGX 021835
FFSHGX

Flash Flood Statement
National Weather Service Houston/Galveston TX
135 PM CDT Sat Oct 2 2021

TXC201-021845-
/O.CAN.KHGX.FF.W.0042.000000T0000Z-211002T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Harris TX-
135 PM CDT Sat Oct 2 2021

...FLASH FLOOD WARNING IS CANCELLED FOR PORTIONS OF NORTHEAST HARRIS 
COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 2999 9528 3007 9520 3001 9517 2991 9528

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 2, 8:27 AM CDTFlash Flood WarningHGXBrazoria38 min
Oct 2, 10:47 AM CDTAreal Flood AdvisoryHGXFort Bend, Harris118 min
Oct 2, 11:49 AM CDTAreal Flood AdvisoryHGXHarris87 min
Oct 2, 12:00 PM CDTAreal Flood AdvisoryHGXHarris93 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.