Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 12, NWS Austin/San Antonio, TX

May 1, 2021Williamson County, Texas

NWS Austin/San Antonio, TX issued this flash flood warning at May 1, 2021, 4:11 PM CDT for Williamson County, Texas. It was in force for 3 hr. 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: May 1, 2021, 4:11 PM CDT (21:11 UTC)
Expired: May 1, 2021, 7:15 PM CDT
In force: 3 hr
Issued by: NWS Austin/San Antonio, TX
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Williamson County, TX

The radar

The Ft Hood radar (KGRK), 32 km from the middle of the area, began a volume at 21:14 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

Time	Report	Where	Remark
May 1, 4:50 PM CDT	FLASH FLOOD	2 Nnw Cedar Park, TX	SEVERAL ROADS CLOSED AT LOW WATER CROSSINGS NEAR PEGGY GARNER PARK TO THE NORTH OF E NEW HOPE DRIVE.

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

The nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 9.2 hours before the alert went out and 257 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 637 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -17 m²/s²
0-3 km storm-relative helicity: -32 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

459 
WGUS54 KEWX 012111
FFWEWX
TXC491-020015-
/O.NEW.KEWX.FF.W.0012.210501T2111Z-210502T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Austin/San Antonio TX
411 PM CDT Sat May 1 2021

The National Weather Service in Austin/San Antonio has issued a

* Flash Flood Warning for...
  Williamson County in south central Texas...

* Until 715 PM CDT.

* At 411 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. The expected rainfall rate is 1 
  to 3 inches in 1 hour. Additional rainfall amounts of 1 to 2 
  inches are possible in the warned area. Flash flooding is ongoing 
  or expected to begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Austin, Round Rock, Cedar Park, Georgetown, Pflugerville, Taylor, 
  Granger, Serenada, Anderson Mill, Leander, Hutto, Bartlett, 
  Jarrell, Thrall, Weir, Georgetown Dam, Sun City, Coupland, Granger 
  Dam and Jonah.

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 3074 9727 3041 9733 3049 9751 3049 9754
      3050 9758 3048 9768 3046 9771 3045 9775
      3043 9775 3043 9777 3047 9784 3053 9787
      3055 9787 3056 9789 3087 9763

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-3 INCHES IN 1 HOUR

$$

PLATT

The office that day

Everything else NWS Austin/San Antonio, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 30, 8:01 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Comal	2 hr
Apr 30, 8:17 PM CDT	Special Weather Statement	EWX	Terrell	28 min
Apr 30, 8:22 PM CDT	Areal Flood Advisory	EWX	Bexar, Guadalupe, Wilson	50 min
Apr 30, 9:12 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Bexar, Guadalupe, Wilson	3 hr
Apr 30, 11:59 PM CDT	Areal Flood Advisory	EWX	Lavaca	3 hr
May 1, 3:09 AM CDT	Areal Flood Advisory	EWX	Lavaca	51 min
May 1, 3:57 AM CDT	Flash Flood Warning Considerable damage threat	EWX	Lavaca	3 hr
May 1, 8:10 AM CDT	Special Weather Statement	EWX	Maverick	35 min
May 1, 8:23 AM CDT	Special Weather Statement	EWX	Dimmit	52 min
May 1, 9:10 AM CDT	Special Weather Statement	EWX	Dimmit	35 min
May 1, 9:24 AM CDT	Special Weather Statement	EWX	Zavala	36 min
May 1, 9:55 AM CDT	Areal Flood Advisory	EWX	Kinney, Maverick, Uvalde, Val Verde, Zavala	3 hr
May 1, 10:02 AM CDT	Special Weather Statement	EWX	Uvalde, Zavala	43 min
May 1, 10:36 AM CDT	Special Weather Statement	EWX	Frio, Medina, Uvalde	54 min
May 1, 10:49 AM CDT	Areal Flood Advisory	EWX	Bandera, Frio, Medina	3 hr
May 1, 11:15 AM CDT	Flash Flood Warning Considerable damage threat	EWX	Medina, Uvalde	4 hr
May 1, 11:18 AM CDT	Areal Flood Advisory	EWX	Uvalde	3 hr
May 1, 11:31 AM CDT	Special Weather Statement	EWX	Atascosa, Bexar, Medina	59 min
May 1, 11:44 AM CDT	Areal Flood Advisory	EWX	Bandera, Gillespie, Kerr, Medina	4 hr
May 1, 12:01 PM CDT	Areal Flood Advisory	EWX	Atascosa	3 hr
May 1, 12:09 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Bexar	4 hr
May 1, 12:30 PM CDT	Special Weather Statement	EWX	Atascosa, Bexar, Wilson	45 min
May 1, 12:40 PM CDT	River Flood Warning	EWX	Bexar	32 hr
May 1, 1:03 PM CDT	Areal Flood Advisory	EWX	Comal	3 hr
May 1, 1:14 PM CDT	Special Weather Statement	EWX	Comal, Guadalupe, Karnes, Wilson	61 min
May 1, 1:22 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Comal, Guadalupe, Wilson	3 hr
May 1, 1:52 PM CDT	Areal Flood Advisory	EWX	Gillespie, Kendall	3 hr
May 1, 2:07 PM CDT	River Flood Warning	EWX	Bexar, Wilson	41 hr
May 1, 2:07 PM CDT	Special Weather Statement	EWX	Caldwell, Gonzales, Guadalupe	38 min
May 1, 2:27 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Caldwell, Hays	3 hr
May 1, 2:44 PM CDT	Areal Flood Advisory	EWX	Gonzales	3 hr
May 1, 2:58 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Bastrop, Travis	3 hr
May 1, 3:11 PM CDT	Flash Flood Warning Considerable damage threat	EWX	Gonzales	3 hr
May 1, 3:39 PM CDT	Areal Flood Advisory	EWX	Lee, Williamson	3 hr
May 1, 4:14 PM CDT	Areal Flood Advisory	EWX	Bexar	2 hr
May 1, 4:25 PM CDT	Areal Flood Advisory	EWX	Lavaca	3 hr
May 1, 4:31 PM CDT	Special Weather Statement	EWX	Bandera, Kerr	44 min
May 1, 6:13 PM CDT	Areal Flood Advisory	EWX	Bandera, Gillespie, Kendall, Kerr	3 hr
May 1, 6:53 PM CDT	Areal Flood Advisory	EWX	Gillespie, Kendall	3 hr

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