A weak cold front moved through South Central Texas and produced widespread thunderstorms. Some of these storms produced damaging wind gusts and heavy rain that led to flash flooding.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS EWX wrote it up.
A weak cold front moved through South Central Texas and produced widespread thunderstorms. Some of these storms produced damaging wind gusts and heavy rain that led to flash flooding.
The local office's own words before the first event, 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 the first event at Aug 18, 7:52 PM CST, 41 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 852 PM CDT SAT AUG 18 2012 .UPDATE... ADJUSTMENTS TO FIRST PERIOD FOR CURRENT TRENDS. && .DISCUSSION... SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ACROSS THE REGION ALONG MULTIPLE WEAK OUTFLOW BOUNDARIES IN ADDITION TO THE FRONTAL BOUNDARY. THROUGH THIS EVENING...THE BEST CHANCES FOR RAIN WILL GENERALLY BE ACROSS EASTERN PORTIONS OF THE CWA BUT ADDITIONAL DEVELOPMENT ACROSS THE BIG COUNTRY WILL BEGIN TO FILL-IN AND DRIFT SOUTHWARD OVERNIGHT. 00Z SOUNDINGS INDICATE PWS OF 1.6 TO NEAR 2 INCHES SPREAD ACROSS THE REGION. MOST AREAS WHICH DO RECEIVE RAIN TONIGHT WILL AVERAGE ABOUT A HALF OF AN INCH...BUT THE HIGH PWS VERIFY THAT SOME OF THE THUNDERSTORMS WILL PRODUCE LOCALLY HEAVY RAIN OF ONE TO TWO INCHES. MOST AREAS WILL GLADLY WELCOME THE RAINFALL...BUT CANNOT RULE OUT THE POSSIBILITY OF MINOR FLOODING SHOULD THE HEAVY RAIN OCCUR OVER URBAN AREAS AND/OR SMALL CREEKS/STREAMS WHICH ARE PRONE TO FLOODING. HAVE TWEAKED FIRST PERIOD POPS/WX/QPF TO ACCOUNT FOR CURRENT TRENDS. ALSO ADJUSTED MIN TEMPS DOWN 0-3 DEGREES BASED ON SFC OBS AND AVAILABLE 00Z GUIDANCE. NEW ZONES WILL BE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 617 PM CDT SAT AUG 18 2012/ AVIATION... UNSETTLED WEATHER PATTERN FOR THE NEXT 24 HOURS AS NWLY FLOW ALOFT BRINGS A SERIES OF DISTURBANCES MOVING SE INTO THE AREA. THEREFORE ALTHOUGH GENERALLY VFR CONDITIONS WILL PREVAIL...PATCHES OF MVFR CIGS WILL DEVELOP LATE TONIGHT AND TOWARD SUNRISE. MUCH DEPENDS ON RESIDUAL OUTFLOW BOUNDARIES WHICH COULD RESULT IN COOLER DRIER AIR LESSENING THE DEVELOPMENT OF MVFR CIGS. OTHERWISE MVFR-IFR CIGS LIKELY IN THE ISOLD-SCT SHRA/TSRA MOVE E-SEWD ACROSS S CENTRAL TX OVERNIGHT AND SUNDAY. WINDS WILL GENERALLY BE S-SELY AT 5-12 KNOTS...OUTFLOW BOUNDARIES WILL RESULT IN BRIEF WIND SHIFTS AND GUSTS OF 30-40 KNOTS POSSIBLE. THE ATMOSPHERE WILL BECOME MORE STABLE WITH SHRA/TSRA DIMINISHING SUNDAY EVENING. PREV DISCUSSION... /ISSUED 243 PM CDT SAT AUG 18 2012/ DISCUSSION... A SERIES OF UPPER DISTURBANCES MOVING SOUTHEAST ACROSS THE AREA TONIGHT WILL GRADUALLY FORCE A LOW LEVEL CONVERGENCE ZONE SOUTH ACROSS THE HILL COUNTRY AND I-35 CORRIDOR AREAS BY LATE TONIGHT. AS MOIST...LOW LEVEL SOUTHERLY FLOW CONTINUE INTO THIS BOUNDARY/ THUNDERSTORM OUTFLOWS...FURTHER DEVELOPMENTS ARE EXPECTED INCLUDING MAINTENANCE OF EXISTING SHOWERS AND STORMS ALONG THE BOUNDARY. THUS...A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TONIGHT...MORE NUMEROUS FROM THE NORTHEAST HILL COUNTRY SOUTHEAST TO ALONG THE I-35 CORRIDOR. GIVEN THE HIGH PRECIPITABLE WATER VALUES AREA-WIDE... EFFICIENT RAIN RATES WILL LEAD TO LOCALLY HEAVY RAINS TONIGHT. AN ADDITIONAL 1 TO 3 INCHES OF RAIN COULD FALL BETWEEN NOW AND NOON SUNDAY FROM THE HILL COUNTRY EASTWARD ACROSS THE I-35 CORRIDOR. LOWS TONIGHT IN THE 70S. THE BOUNDARY/OUTFLOWS WILL CONTINUE PUSHING SOUTH ON SUNDAY AS DISTURBANCES ALOFT PERSIST. MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE SUNDAY AS AN UPPER TROUGH DIGS FURTHER SOUTH INTO EAST TEXAS PUSHING A COLD FRONT INTO SOUTH CENTRAL TEXAS DURING THE AFTERNOON. HIGH TEMPERATURES SUNDAY WILL LOWER TO NEAR 90 OVER THE HILL COUNTRY TO THE LOW AND MID 90S ELSEWHERE EXCEPT UPPER 90S SOUTH CENTRAL AND SOUTHWEST PORTIONS. AS THE UPPER TROUGH CONTINUES ITS DIG TOMORROW NIGHT...DRIER AIR WILL ADVECT SOUTH WITH DECREASING CLOUDINESS BECOMING MOSTLY SUNNY AND HOT AGAIN MONDAY...WITH LOWER HUMIDITIES. LOWS SUNDAY NIGHT WILL SLIP INTO THE 60S ACROSS THE HILL COUNTRY AND TO NEAR 70 OUTSIDE OF THE METRO AREAS OF THE I-35 CORRIDOR. HIGHS MONDAY LOW 90S HILLS TO MID TO UPPER 90S ELSEWHERE. MOSTLY CLEAR AND COOLER MONDAY NIGHT AS LOWS SLIP INTO THE 60S TO NEAR 70 ACROSS THE HILL COUNTRY TO ALONG AND EAST OF THE I-35 CORRIDOR. CONTINUED DRY TUESDAY AS ANOTHER DISTURBANCE DROPS IN OVER EASTERN SECTIONS WITH INCREASING CLOUDINESS. AN UPPER RIDGE TO THE WEST WILL KEEP MUCH OF THE REGION DRY AND VERY WARM TO HOT THROUGH THE MID TO LATTER PART OF NEXT WEEK...HOWEVER HUMIDITIES (AND LOW TEMPERATURES) WILL TREND UPWARD BY WEDNESDAY AS SOUTHERLY GULF FLOW RETURNS. THE COMBINED GULF MOISTURE AND DAYTIME HEATING MAY EVENTUALLY TRIGGER SOME AIR-MASS TYPE SHOWERS AND THUNDERSTORMS BY FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 74 95 73 95 70 / 60 40 10 0 0 AUSTIN BERGSTROM INTL AIRPORT 72 94 71 95 67 / 50 40 10 0 0 NEW BRAUNFELS MUNI AIRPORT 73 93 71 94 66 / 50 40 10 - 0 BURNET MUNI AIRPORT 72 94 70 94 69 / 60 40 - 0 0 DEL RIO INTL AIRPORT 78 97 76 99 75 / 30 40 20 10 0 GEORGETOWN MUNI AIRPORT 73 94 71 93 69 / 60 40 - 0 0 HONDO MUNI AIRPORT 72 94 71 96 67 / 50 40 10 - 0 SAN MARCOS MUNI AIRPORT 74 94 71 95 67 / 50 40 10 - 0 LA GRANGE - FAYETTE REGIONAL 76 95 72 94 69 / 40 60 10 - 0 SAN ANTONIO INTL AIRPORT 75 94 74 95 71 / 50 40 10 - 0 STINSON MUNI AIRPORT 74 96 73 97 70 / 50 40 10 - 0 && .EWX WATCHES/WARNINGS/ADVISORIES... NONE. && MESOSCALE/AVIATION...01 SYNOPTIC/GRIDS...25 PUBLIC SERVICE/DATA COLLECTION...31
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 354 PM CDT SAT AUG 18 2012 TXZ171>173-183>194-202>209-217>225-228-192100- 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- 354 PM CDT SAT AUG 18 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS. .DAY ONE...TONIGHT... SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED LATER TONIGHT ESPECIALLY ACROSS NORTHERN AREAS OF SOUTH CENTRAL TEXAS. WIND GUSTS UP TO 50 MPH AS WELL AS LOCALIZED HEAVY RAINS ARE POSSIBLE. RAINFALL AMOUNTS THROUGH EARLY SUNDAY COULD RANGE FROM 1 TO 3 INCHES. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY... SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE ON SUNDAY MORNING AND SUNDAY AFTERNOON AS A WEAK COOL FRONT PUSHES THROUGH THE AREA. WIND GUSTS UP TO 50 MPH AS WELL AS LOCALIZED HEAVY RAINS ARE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
449 PM CDT SAT AUG 18 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 PM HEAVY RAIN SUN CITY 30.67N 97.71W
08/18/2012 M2.17 INCH WILLIAMSON TX AMATEUR RADIO
1 HR 45 MIN.
&&
EVENT NUMBER EWX1200444
JPBSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 818 PM CDT SAT AUG 18 2012 TXZ189-190-190200- BLANCO-KENDALL- 818 PM CDT SAT AUG 18 2012 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN BLANCO AND NORTHEASTERN KENDALL COUNTIES UNTIL 900 PM CDT... AT 809 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A STRONG THUNDERSTORM NEAR FLUGRATH...OR 6 MILES SOUTHWEST OF BLANCO... MOVING EAST AT 15 MPH. WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... BLANCO... TWIN SISTERS... PAYTON... IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. THE HEAVY RAIN MAY FLOOD LOW LYING AREAS SUCH AS DITCHES...LOW WATER CROSSINGS AND UNDERPASSES. DO NOT DRIVE YOUR VEHICLE ACROSS FLOODED ROADWAYS.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 819 PM CDT SAT AUG 18 2012 TXZ193-208-209-223-190145- BASTROP-CALDWELL-FAYETTE-GONZALES- 819 PM CDT SAT AUG 18 2012 ...SIGNIFICANT WEATHER ADVISORY FOR EXTREME SOUTHERN BASTROP... EASTERN CALDWELL...NORTHEASTERN GONZALES AND EXTREME WESTERN FAYETTE COUNTIES UNTIL 845 PM CDT... AT 814 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A STRONG THUNDERSTORM 6 MILES NORTHWEST OF WAELDER...OR 16 MILES EAST OF LULING...MOVING NORTHEAST AT 20 MPH. WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... DELHI... JEDDO... IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. THE HEAVY RAIN MAY FLOOD LOW LYING AREAS SUCH AS DITCHES...LOW WATER CROSSINGS AND UNDERPASSES. DO NOT DRIVE YOUR VEHICLE ACROSS FLOODED ROADWAYS.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 929 PM CDT SAT AUG 18 2012 TXZ193-190300- BASTROP- 929 PM CDT SAT AUG 18 2012 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL BASTROP COUNTY UNTIL 1000 PM CDT... AT 922 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A STRONG THUNDERSTORM NEAR ROSANKY...OR 7 MILES SOUTHWEST OF SMITHVILLE...MOVING NORTH AT 10 MPH. WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... SMITHVILLE... UPTON... ALUM CREEK... IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. THE HEAVY RAIN MAY FLOOD LOW LYING AREAS SUCH AS DITCHES...LOW WATER CROSSINGS AND UNDERPASSES. DO NOT DRIVE YOUR VEHICLE ACROSS FLOODED ROADWAYS.
The Austin/San Antonio radar (KEWX), 75 km away, was scanning. The volume nearest the first event began at 02:32 UTC.
8 flash flood, 1 thunderstorm wind, 1 lightning. Local standard time, as filed.
A thunderstorm produced wind gusts estimated at 58 mph that uprooted a large tree and peeled a tin roof off a barn.
A thunderstorm produced a lightning strike that started a house fire in San Antonio.
Thunderstorms produced heavy rain that caused flash flooding closing the intersection of Airport Rd and Lakeway Dr in Georgetown.
Thunderstorms produced heavy rain that caused flash flooding closing FM 971 near Berry Creek.
Thunderstorms produced heavy rain that caused flash flooding closing Hwy 195 near Florence.
Thunderstorms produced heavy rain that caused flash flooding closing Amity Rd at Roland Ave in San Antonio.
Thunderstorms produced heavy rain that caused flash flooding closing Brook Valley Dr at Ray Ellison Blvd in San Antonio.
Thunderstorms produced heavy rain that caused flash flooding closing Pinn Rd from W. Commerce St to Hwy 151 in San Antonio.
Thunderstorms produced heavy rain that caused flash flooding affecting both the northbound and southbound lanes of the lower level of I-35 near San Pedro Ave in San Antonio.
Thunderstorms produced heavy rain that caused flash flooding closing several roads around the county including FM 471 and CR 741.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Texas in 2012Every state in 2012This day in weather historyWarnings in Texas, August 2012
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 398064, 398066, 398077, 398078, 398079, 398093, 398096, 398109, 398111, 398114.