Alert archive / Texas / Flash Flood Watches in 2009

Flash Flood Watch 1, NWS Austin/San Antonio, TX

April 17, 200916 counties in Texas

NWS Austin/San Antonio, TX issued this flash flood watch at Apr 17, 2009, 9:20 PM CDT for 16 counties in Texas. It took effect at Apr 18, 2009, 6:00 AM CDT. It was in force for 11 hr.

The area

The counties it named.

The facts

Issued: Apr 17, 2009, 9:20 PM CDT (02:20 UTC)
In effect from: Apr 18, 2009, 6:00 AM CDT
Expired: Apr 18, 2009, 4:44 PM CDT
In force: 11 hr
Issued by: NWS Austin/San Antonio, TX
Flood severity: None

Counties Atascosa County, TX, Bastrop County, TX, Bexar County, TX, Caldwell County, TX, Comal County, TX, DeWitt County, TX, Fayette County, TX, Gonzales County, TX, Guadalupe County, TX, Hays County, TX, Karnes County, TX, Lavaca County, TX, Lee County, TX, Travis County, TX, Williamson County, TX, Wilson County, TX

The radar

The Austin/San Antonio radar (KEWX), 32 km from the middle of the area, began a volume at 02:21 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, 2.3 hours before the alert went out and 220 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: 3044 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 729 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: -85 m²/s²
Significant tornado parameter: -0.6
Supercell composite: -2.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Austin/San Antonio, TX wrote its last area forecast discussion before this flash flood watch went out at Apr 17, 6:29 PM CDT, 2 hours 51 minutes earlier.

Area forecast discussion, Apr 17, 6:29 PM CDT, 2 hours 51 minutes before

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Hazardous weather outlook, Apr 17, 5:31 AM CDT, 15 hours 49 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
531 AM CDT FRI APR 17 2009

TXZ171>173-183>194-202>209-217>225-228-181045-
LLANO-BURNET-WILLIAMSON-VAL VERDE-EDWARDS-REAL-KERR-BANDERA-
GILLESPIE-KENDALL-BLANCO-HAYS-TRAVIS-BASTROP-LEE-KINNEY-UVALDE-
MEDINA-BEXAR-COMAL-GUADALUPE-CALDWELL-FAYETTE-MAVERICK-ZAVALA-
FRIO-ATASCOSA-WILSON-KARNES-GONZALES-DE WITT-LAVACA-DIMMIT-
531 AM CDT FRI APR 17 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...TODAY AND TONIGHT...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY AND TONIGHT
FOR SOUTH CENTRAL TEXAS. STRONG TO SEVERE THUNDERSTORMS ARE
EXPECTED TO MOVE THROUGH THE AREA...WITH MUCH OF THE ACTIVITY IN
ORGANIZED COMPLEXES TODAY AND TONIGHT. LARGE HAIL...DAMAGING
WINDS...ISOLATED TORNADOES...AND ISOLATED HEAVY RAINFALL TOTALS
OVER 2 INCHES ARE POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY...
SEVERE THUNDERSTORMS...AND LOCALLY HEAVY RAINFALL TOTALS OF 2 TO 4
INCHES ARE POSSIBLE SATURDAY. MOST OF THE HEAVY RAIN AND SEVERE
WEATHER IS EXPECTED TO FOCUS EAST OF A KERRVILLE TO PEARSALL LINE.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED TODAY...TONIGHT...OR SATURDAY.

In the hours before

Local storm report, Apr 17, 5:00 PM CDT, 4 hours 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
500 PM CDT FRI APR 17 2009

..TIME..    ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE..    ....MAG....     ..COUNTY LOCATION.. ST.. ...SOURCE....
            ..REMARKS..

0245 PM     FLASH FLOOD      MOULTON                 29.57N  97.15W
04/17/2009                   LAVACA             TX   LAW ENFORCEMENT

            MOULTON POLICE CHIEF REPORTS STREET FLOODING IN THE
            CITY FROM OVER 7 INCHES OF RAIN.

&&

EVENT NUMBER 00505

SBS

Local storm report, Apr 17, 5:02 PM CDT, 4 hours 18 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
502 PM CDT FRI APR 17 2009

..TIME..    ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE..    ....MAG....     ..COUNTY LOCATION.. ST.. ...SOURCE....
            ..REMARKS..

0245 PM     HEAVY RAIN       1 NW MOULTON            29.58N  97.16W
04/17/2009  M9.75 INCH       LAVACA             TX   LAW ENFORCEMENT

            HEAVY RAIN ALONG STATE HIGHWAY 1680. AMOUNT IS FROM
            MIDNIGHT.

&&

EVENT NUMBER 00506

SBS

Local storm report, Apr 17, 5:06 PM CDT, 4 hours 14 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
506 PM CDT FRI APR 17 2009

..TIME..    ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE..    ....MAG....     ..COUNTY LOCATION.. ST.. ...SOURCE....
            ..REMARKS..

0245 PM     FLASH FLOOD      MOULTON                 29.57N  97.15W
04/17/2009                   LAVACA             TX   LAW ENFORCEMENT

            STATE HIGHWAY 532 CLOSED FROM SOUTHWEST OF MOULTON TO
            SOUTHEAST OF MOULTON.

&&

EVENT NUMBER 00507

SBS

Local storm report, Apr 17, 5:31 PM CDT, 3 hours 49 minutes before

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Local storm report, Apr 17, 5:36 PM CDT, 3 hours 44 minutes before

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Special weather statement, Apr 17, 6:16 PM CDT, 3 hours 4 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 18, 3:03 AM CDT	Severe Thunderstorm Warning	EWX	Val Verde	27 min
Apr 18, 3:45 AM CDT	Severe Thunderstorm Warning	EWX	Uvalde, Zavala	60 min
Apr 18, 4:57 AM CDT	Areal Flood Advisory	EWX	Frio, Medina, Uvalde, Zavala	2 hr
Apr 18, 5:11 AM CDT	Areal Flood Advisory	EWX	Atascosa, Caldwell, Gonzales, Guadalupe, Wilson	2 hr
Apr 18, 5:46 AM CDT	Areal Flood Advisory	EWX	Bexar	119 min
Apr 18, 5:49 AM CDT	Severe Thunderstorm Warning	EWX	Dimmit	56 min
Apr 18, 6:45 AM CDT	Flash Flood Warning	EWX	Bastrop, Bexar, Caldwell, Fayette, Gonzales, Guadalupe and 2 more	4 hr
Apr 18, 7:47 AM CDT	Flash Flood Warning	EWX	DeWitt, Fayette, Gonzales, Karnes, Lavaca, Lee and 1 more	4 hr
Apr 18, 8:44 AM CDT	Severe Thunderstorm Warning	EWX	DeWitt, Lavaca	29 min
Apr 18, 10:50 AM CDT	Areal Flood Advisory	EWX	Atascosa, Bastrop, Caldwell, Fayette, Gonzales, Guadalupe and 1 more	115 min
Apr 18, 11:45 AM CDT	Flash Flood Warning	EWX	DeWitt, Gonzales, Lavaca	3 hr
Apr 18, 12:01 PM CDT	River Flood Warning	EWX	Caldwell, Gonzales	24 hr
Apr 18, 4:13 PM CDT	River Flood Warning	EWX	DeWitt	60 hr

Nearby

Flash Flood Watches in Texas, 2009 Every flash flood watch in 2009

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.