Alert archive / Texas / Flash Flood Warnings in 2018

Flash Flood Warning 7, NWS Austin/San Antonio, TX

May 20, 2018Edwards County, Val Verde County, Texas

NWS Austin/San Antonio, TX issued this flash flood warning at May 20, 2018, 12:56 PM CDT for Edwards County, Val Verde County, 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 20, 2018, 12:56 PM CDT (17:56 UTC)
Expired: May 20, 2018, 4:00 PM CDT
In force: 3 hr
Issued by: NWS Austin/San Antonio, TX
Area: Storm-based polygon
Flood severity: None

Counties Edwards County, TX, Val Verde County, TX

The radar

The Laughlin AFB radar (KDFX), 79 km from the middle of the area, began a volume at 17:58 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

Del Rio, TX (KDLF), launched 12:00Z, 5.9 hours before the alert went out and 60 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: 1390 J/kg
Mixed-layer CIN: -41 J/kg
Mixed-layer LCL: 732 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 111 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 4.8

Open this sounding in Storm Lab

The text

As transmitted.

753 
WGUS54 KEWX 201756
FFWEWX
TXC137-465-202100-
/O.NEW.KEWX.FF.W.0007.180520T1756Z-180520T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Austin/San Antonio TX
1256 PM CDT SUN MAY 20 2018

The National Weather Service in Austin San Antonio has issued a

* Flash Flood Warning for...
  Western Edwards County in south central Texas...
  Northeastern Val Verde County in south central Texas...

* Until 400 PM CDT

* At 1253 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. One to two inches of rain have 
  already fallen across northeastern Val Verde county and 
  southwestern Edwards County. Radar estimates of rainfall rates of 
  three to four inches per hour with the ongoing thunderstorms. 
  Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Loma Alta, Carta Valley, Devils Shores, Vinegarone, Devils River
  SNA - Big Satan, Kickapoo Cavern State Park and Devils River SNA -
  Del Norte.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 2962 10095 3028 10094 3029 10028 2963 10029

$$

AAT

The office that day

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

Issued	Product	Office	Counties	Lasted
May 20, 8:33 AM CDT	Tornado Warning	EWX	Williamson	27 min
May 20, 10:47 AM CDT	Areal Flood Advisory	EWX	Burnet	3 hr
May 20, 12:09 PM CDT	Areal Flood Advisory	EWX	Val Verde	3 hr
May 20, 12:20 PM CDT	Special Weather Statement	EWX	Edwards	55 min
May 20, 1:03 PM CDT	Special Weather Statement	EWX	Kinney	42 min
May 20, 1:04 PM CDT	Areal Flood Advisory	EWX	Comal, Hays	116 min
May 20, 1:32 PM CDT	Severe Thunderstorm Warning	EWX	Kinney, Uvalde	58 min
May 20, 1:39 PM CDT	Areal Flood Advisory	EWX	Bastrop, Travis	3 hr
May 20, 1:59 PM CDT	Areal Flood Advisory	EWX	Kinney	2 hr
May 20, 2:31 PM CDT	Severe Thunderstorm Warning	EWX	Uvalde	59 min
May 20, 3:14 PM CDT	Areal Flood Advisory	EWX	Uvalde	3 hr
May 20, 3:30 PM CDT	Special Weather Statement	EWX	Medina	60 min
May 20, 4:01 PM CDT	Areal Flood Advisory	EWX	Medina	3 hr
May 20, 4:07 PM CDT	Areal Flood Advisory	EWX	DeWitt, Fayette, Gonzales, Lavaca	3 hr
May 20, 5:10 PM CDT	Areal Flood Advisory	EWX	Atascosa, Bexar, Karnes, Wilson	4 hr
May 20, 5:10 PM CDT	Special Weather Statement	EWX	Atascosa	50 min
May 20, 5:31 PM CDT	Special Weather Statement	EWX	Bexar	44 min
May 20, 5:56 PM CDT	Special Weather Statement	EWX	Atascosa, Wilson	49 min

Nearby

Flash Flood Warnings in Texas, 2018 Every flash flood warning in 2018

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.