Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS Houston/Galveston, TX

May 1, 20214 counties in Texas

NWS Houston/Galveston, TX issued this flash flood warning at May 1, 2021, 5:06 AM CDT for 4 counties in 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
May 1, 2021, 5:06 AM CDT (10:06 UTC)
Expired
May 1, 2021, 8:15 AM CDT
In force
3 hr
Issued by
NWS Houston/Galveston, TX
Area
Storm-based polygon
Flood severity
None

Counties Brazoria County, TX, Fort Bend County, TX, Matagorda County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 97 km from the middle of the area, began a volume at 10:09 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, 10.1 hours before the alert went out and 214 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 2021-05-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 42 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 2021-05-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 square meters per square second.19395878Sfc1 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
42 J/kg
Mixed-layer CIN
-278 J/kg
Mixed-layer LCL
901 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
69 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

The text

As transmitted.

509 
WGUS54 KHGX 011006
FFWHGX
TXC039-157-321-481-011315-
/O.NEW.KHGX.FF.W.0002.210501T1006Z-210501T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
506 AM CDT Sat May 1 2021

The National Weather Service in League City has issued a

* Flash Flood Warning for...
  West Central Brazoria County in southeastern Texas...
  Southwestern Fort Bend County in southeastern Texas...
  North Central Matagorda County in southeastern Texas...
  Northeastern Wharton County in southeastern Texas...

* Until 815 AM CDT.

* At 506 AM CDT, Doppler radar indicated slow moving thunderstorms 
  producing heavy rain across the warned area. 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...
  Wharton, East Bernard, Kendleton, Boling-Iago, Pierce, Hungerford 
  and Egypt.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

Excessive runoff from heavy rainfall will cause flooding of small 
creeks and streams, country roads, farmland, and other low lying 
spots.

&&

LAT...LON 2923 9625 2931 9628 2946 9629 2954 9624
      2957 9608 2951 9599 2936 9590 2927 9582
      2918 9580 2909 9582 2908 9589 2916 9609
      2920 9619

FLASH FLOOD...RADAR INDICATED

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 30, 8:36 PM CDTRiver Flood WarningHGXMatagorda, Wharton65 hr
May 1, 3:44 AM CDTAreal Flood AdvisoryHGXAustin, Brazoria, Colorado, Fort Bend, Jackson, Matagorda and 1 more3 hr
May 1, 4:43 AM CDTRip Current StatementHGXBrazoria, Galveston, Matagorda17 hr
May 1, 4:50 AM CDTSmall Craft AdvisoryHGX17 hr
May 1, 6:01 AM CDTSpecial Marine WarningHGX59 min
May 1, 6:08 AM CDTAreal Flood WarningHGXAustin, Brazoria, Fort Bend, Matagorda, Wharton3 hr
May 1, 7:49 AM CDTAreal Flood AdvisoryHGXBrazoria, Fort Bend, Harris, Matagorda3 hr
May 1, 7:59 AM CDTAreal Flood AdvisoryHGXAustin, Brazoria, Colorado, Fort Bend, Matagorda, Wharton4 hr
May 1, 8:04 AM CDTRiver Flood WarningHGXBrazoria, Fort Bend, Wharton7 days
May 1, 9:09 AM CDTAreal Flood WarningHGXBrazoria, Fort Bend, Matagorda, Wharton3 hr
May 1, 9:32 AM CDTRiver Flood WarningHGXJackson72 hr
May 1, 9:32 AM CDTRiver Flood WarningHGXJackson, Wharton12 hr
May 1, 9:32 AM CDTRiver Flood WarningHGXColorado, Jackson, Wharton52 hr
May 1, 9:55 AM CDTRiver Flood WarningHGXHarris, Montgomery24 hr
May 1, 12:00 PM CDTAreal Flood WarningHGXBrazoria, Matagorda3 hr
May 1, 12:37 PM CDTAreal Flood AdvisoryHGXBrazoria, Fort Bend, Matagorda, Wharton2 hr
May 1, 1:53 PM CDTRiver Flood WarningHGXBrazoria21 days
May 1, 1:53 PM CDTRiver Flood WarningHGXAustin, Colorado, Fort Bend, Wharton3 days
May 1, 2:15 PM CDTRiver Flood WarningHGXLavaca21 days
May 1, 2:25 PM CDTAreal Flood AdvisoryHGXWaller8 hr
May 1, 2:29 PM CDTAreal Flood AdvisoryHGXWaller8 hr
May 1, 4:13 PM CDTAreal Flood AdvisoryHGXMontgomery6 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.