Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 46, NWS Austin/San Antonio, TX

August 2, 2021Bexar County, Comal County, Kendall County, Texas

NWS Austin/San Antonio, TX issued this flash flood warning at Aug 2, 2021, 7:47 AM CDT for Bexar County, Comal County, Kendall County, Texas. It was in force for 4 hr. 5 reports 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: Aug 2, 2021, 7:47 AM CDT (12:47 UTC)
Expired: Aug 2, 2021, 12:15 PM CDT
In force: 4 hr
Issued by: NWS Austin/San Antonio, TX
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Bexar County, TX, Comal County, TX, Kendall County, TX

The radar

The Austin/San Antonio radar (KEWX), 69 km from the middle of the area, began a volume at 12:50 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
Aug 2, 8:19 AM CDT	FLASH FLOOD	2 Nw Cross Mountain, TX	HUNTRESS LANE WEST OF SCENIC LOOP CLOSED DUE TO FLOODING.
Aug 2, 8:21 AM CDT	FLASH FLOOD	4 W Scenic Oaks, TX	TOUTANT BEAUREGARD CLOSED AT BALCONES CREEK DUE TO FLOODING.
Aug 2, 8:23 AM CDT	FLASH FLOOD	2 Ese Scenic Oaks, TX	OLD FREDERICKSBURG NORTH OF LOST CREEK GAP CLOSED DUE TO FLOODING.
Aug 2, 8:45 AM CDT	HEAVY RAIN 5.18	2 Nw Fair Oaks Ranch, TX	24 HOUR RAINFALL AS OF 845 AM.
Aug 2, 9:31 AM CDT	FLASH FLOOD	2 Ssw The Dominion, TX	HEUERMANN RD NORTH OF BABCOCK RD CLOSED DUE TO FLOODING.

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

The nearest sounding before it

Del Rio, TX (KDRT), launched 12:00Z, 0.8 hours before the alert went out and 206 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: 241 J/kg
Mixed-layer CIN: -123 J/kg
Mixed-layer LCL: 905 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 26 m²/s²
0-3 km storm-relative helicity: 75 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

336 
WGUS54 KEWX 021247
FFWEWX
TXC029-091-259-021715-
/O.NEW.KEWX.FF.W.0046.210802T1247Z-210802T1715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Austin/San Antonio TX
747 AM CDT Mon Aug 2 2021

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

* Flash Flood Warning for...
  Northwestern Bexar County in south central Texas...
  West Central Comal County in south central Texas...
  Southwestern Kendall County in south central Texas...

* Until 1215 PM CDT.

* At 747 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area which covers the Boerne, Fair 
  Oaks Ranch, Scenic Oaks, and San Geronimo areas. Between 2 and 4 
  inches of rain have fallen. Additional rainfall amounts of 1 to 3 
  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...
  San Antonio, Boerne, Helotes, Fair Oaks Ranch, Cross Mountain, 
  Leon Springs, The Dominion, Government Canyon State Natural Area, 
  Bergheim, Grey Forest, Scenic Oaks, Cascade Caverns, Fiesta Texas 
  and San Geronimo.

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 2973 9881 2983 9881 2984 9853 2975 9853
      2961 9854 2952 9880 2957 9881 2961 9881
      2964 9881 2969 9881 2970 9880 2972 9878

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 1, 7:53 PM CDT	Areal Flood Advisory	EWX	Bandera, Real	3 hr
Aug 1, 11:02 PM CDT	Areal Flood Advisory	EWX	Kendall	3 hr
Aug 2, 12:27 AM CDT	Areal Flood Advisory	EWX	Bastrop, Hays, Travis	3 hr
Aug 2, 3:45 AM CDT	Areal Flood Advisory	EWX	Comal, Guadalupe, Hays	4 hr
Aug 2, 3:53 AM CDT	Areal Flood Advisory	EWX	Edwards, Kinney	4 hr
Aug 2, 4:09 AM CDT	Flash Flood Warning Considerable damage threat	EWX	Comal, Guadalupe	4 hr
Aug 2, 4:13 AM CDT	Areal Flood Advisory	EWX	Uvalde	4 hr
Aug 2, 5:41 AM CDT	Flash Flood Warning Considerable damage threat	EWX	Guadalupe	4 hr
Aug 2, 5:45 AM CDT	Areal Flood Advisory	EWX	Bexar, Guadalupe, Wilson	3 hr
Aug 2, 5:51 AM CDT	Areal Flood Advisory	EWX	Bandera, Real	3 hr
Aug 2, 5:57 AM CDT	Areal Flood Advisory	EWX	Comal, Hays	4 hr
Aug 2, 6:37 AM CDT	Areal Flood Advisory	EWX	Bandera, Kerr, Medina	4 hr
Aug 2, 6:37 AM CDT	Flash Flood Warning Considerable damage threat	EWX	Comal	5 hr
Aug 2, 6:52 AM CDT	Flash Flood Warning Considerable damage threat	EWX	Hays	3 hr
Aug 2, 7:15 AM CDT	Areal Flood Advisory	EWX	Bandera, Bexar, Comal, Kendall, Kerr, Medina	5 hr
Aug 2, 7:29 AM CDT	Special Weather Statement	EWX	Bexar	46 min
Aug 2, 8:13 AM CDT	Areal Flood Advisory	EWX	Kinney	3 hr
Aug 2, 8:15 AM CDT	Areal Flood Advisory	EWX	Bastrop, Lee, Travis, Williamson	5 hr
Aug 2, 8:18 AM CDT	Special Weather Statement	EWX	Bexar, Comal	42 min
Aug 2, 8:26 AM CDT	Areal Flood Advisory	EWX	Bexar, Comal, Kendall	4 hr
Aug 2, 8:36 AM CDT	Areal Flood Advisory	EWX	Bexar	4 hr
Aug 2, 9:16 AM CDT	Areal Flood Advisory	EWX	Blanco, Hays, Travis	3 hr
Aug 2, 10:25 AM CDT	Areal Flood Advisory	EWX	Kinney, Maverick, Uvalde, Zavala	3 hr
Aug 2, 2:45 PM CDT	Areal Flood Advisory	EWX	Bandera, Edwards, Kerr, Real, Val Verde	3 hr
Aug 2, 4:56 PM CDT	Areal Flood Advisory	EWX	Travis, Williamson	3 hr
Aug 2, 5:12 PM CDT	Areal Flood Advisory	EWX	Blanco, Hays	3 hr
Aug 2, 6:19 PM CDT	Areal Flood Advisory	EWX	Caldwell, Hays, Travis	2 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.