Alert archive / Texas / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 75, NWS Houston/Galveston, TX

July 21, 2021Brazoria County, Galveston County, Harris County, Texas

NWS Houston/Galveston, TX issued this severe thunderstorm warning at Jul 21, 2021, 1:39 PM CDT for Brazoria County, Galveston County, Harris County, Texas. It was in force for 32 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
Jul 21, 2021, 1:39 PM CDT (18:39 UTC)
Expired
Jul 21, 2021, 2:11 PM CDT
In force
32 min
Issued by
NWS Houston/Galveston, TX
Area
Storm-based polygon
Hail
0.88 in
Wind
60.0 mph

Counties Brazoria County, TX, Galveston County, TX, Harris County, TX

The radar

The Houston radar (KHGX), 16 km from the middle of the area, began a volume at 18:43 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, 6.7 hours before the alert went out and 209 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 2021-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 539 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 2021-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 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
539 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
805 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
12 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

406 
WUUS54 KHGX 211839
SVRHGX
TXC039-167-201-211930-
/O.NEW.KHGX.SV.W.0075.210721T1839Z-210721T1930Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Houston/Galveston TX
139 PM CDT Wed Jul 21 2021

The National Weather Service in League City has issued a

* Severe Thunderstorm Warning for...
  West central Galveston County in southeastern Texas...
  Northeastern Brazoria County in southeastern Texas...
  South central Harris County in southeastern Texas...

* Until 230 PM CDT.

* At 138 PM CDT, a severe thunderstorm was located over southwestern
  Friendswood, moving west at 10 mph.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Pearland, southwestern League City, Friendswood, Alvin, Santa Fe,
  Webster, Manvel, Greater Hobby Area, southwestern South Belt /
  Ellington, southwestern Clear Lake, Brookside Village, Iowa Colony,
  Hillcrest and Minnetex.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Heavy rainfall is occurring with this storm, and may lead to 
localized street flooding. Do not drive your vehicle through flooded 
roadways.

&&

LAT...LON 2954 9511 2938 9516 2937 9540 2951 9539
      2963 9531
TIME...MOT...LOC 1838Z 102DEG 11KT 2949 9523 

HAIL...0.88IN
WIND...60MPH
 
$$
1 follow-up statement
642 
WWUS54 KHGX 211911
SVSHGX

Severe Weather Statement
National Weather Service Houston/Galveston TX
211 PM CDT Wed Jul 21 2021

TXC039-167-201-211919-
/O.CAN.KHGX.SV.W.0075.000000T0000Z-210721T1930Z/
Galveston TX-Brazoria TX-Harris TX-
211 PM CDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL GALVESTON...
NORTHEASTERN BRAZORIA AND SOUTH CENTRAL HARRIS COUNTIES IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.  However heavy rain and 
gusty winds are still possible with new thunderstorms that may pop 
up in the vicinity.

LAT...LON 2954 9511 2938 9516 2937 9540 2951 9539
      2963 9531
TIME...MOT...LOC 1908Z 102DEG 11KT 2951 9534 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 8:46 PM CDTRiver Flood WarningHGXBrazoria, Fort Bend, Wharton35 hr
Jul 21, 1:06 PM CDTAreal Flood AdvisoryHGXBrazoria, Fort Bend, Harris114 min
Jul 21, 1:17 PM CDTSpecial Weather StatementHGXFort Bend43 min
Jul 21, 1:33 PM CDTSpecial Weather StatementHGXBrazoria57 min
Jul 21, 1:46 PM CDTAreal Flood AdvisoryHGXBrazoria, Galveston, Harris74 min
Jul 21, 2:34 PM CDTAreal Flood AdvisoryHGXHarris116 min
Jul 21, 2:34 PM CDTSpecial Weather StatementHGXHarris26 min
Jul 21, 3:09 PM CDTFlash Flood WarningHGXHarris51 min

Nearby

Severe Thunderstorm Warnings in Texas, 2021Every severe thunderstorm 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.