A squall line developed from Montgomery County to Harris County (from about Conroe to just North of the Houston City limit). The showers and thunderstorms developed from many places reaching their convective temperatures in the afternoon, kind of like a classic loaded gun sounding case, when the cap is broken in the afternoon.
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 HGX wrote it up.
A squall line developed from Montgomery County to Harris County (from about Conroe to just North of the Houston City limit). The showers and thunderstorms developed from many places reaching their convective temperatures in the afternoon, kind of like a classic loaded gun sounding case, when the cap is broken in the afternoon.
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 Houston/Galveston, TX wrote its last area forecast discussion before the first event at Jul 17, 11:27 AM CST, 2 hours 53 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 1227 PM CDT TUE JUL 17 2012 .DISCUSSION... SEE AVIATION FOR 18Z TAF ISSUANCE && .AVIATION... SCATTERED CONVECTION BEGINNING TO INCREASE IN COVERAGE ACROSS SOUTHEAST TEXAS THIS AFTERNOON BUT BEST COVERAGE REMAINS OFF TO OUR WEST. WILL CARRY VCTS WORDING FOR ALL INLAND SITES WITH THE EXCEPTION OF UTS THIS AFTERNOON. WITH THE BETTER COVERAGE TO OUR WEST WILL LEAVE OUT ANY TEMPO MENTION FOR NOW AND SEE HOW THINGS DEVELOP THIS AFTERNOON. EXPECTING CONVECTION TO END AROUND SUNSET SIMILAR TO THE PAST FEW DAYS WITH GENERALLY LIGHT WINDS OVERNIGHT. MODELS ARE BRINGING IN SOME LOW CLOUDS WITH THE MOST EXTENSIVE COVERAGE ACROSS COLLEGE STATION. WILL MENTION SCATTERED LOW CLOUDS FOR NOW BUT WOULD NOT BE SURPRISED TO SEE A BRIEF PERIOD WITH MVFR CIGS FOR CLL AROUND SUNRISE. ELSEWHERE CONDITIONS SHOULD REMAIN VFR ASIDE FROM SOME BRIEF MVFR VSBYS FOR CXO. EXPECTING SOME ISOLATED CONVECTION TO DEVELOP AGAIN TOMORROW AFTERNOON BUT FELT THAT THE AMOUNT OF COVERAGE DID NOT WARRANT A PROB30 FOR IAH WITH THIS ISSUANCE. 38 && .PREV DISCUSSION... /ISSUED 1115 AM CDT TUE JUL 17 2012/ DISCUSSION... SHOWERS HAVE BEEN SLOW TO DEVELOP TODAY AND SUBSIDENCE ON THE INCREASE. PW STILL RUNNING AROUND 2" AND WITH HEATING TODAY EXPECT THE SCATTERED THUNDERSTORMS TO DEVELOP AFTER TEMPERATURES REACH 90-91 MORE EASILY. INCREASED CLOUD COVER OVER THE FAR WESTERN PORTIONS OF THE AREA WHERE SHRA/TSRA FORMING AND MOVING NORTH FROM THE COASTAL BEND AND DECREASED CLOUD COVER FOR TONIGHT AFTER 8 PM WITH DISSIPATION OF STORMS. LOOKING DRIER AND WARMER TOMORROW AND MAY BE LOWERING POPS IN THE AFTERNOON PACKAGE FOR THE NEXT FEW DAYS IF MODELS CONTINUE TO PAINT THE INCREASING SUBSIDENCE AS CONVINCINGLY AS PREVIOUS RUNS HAVE DONE. 45 PREV DISCUSSION... /ISSUED 632 AM CDT TUE JUL 17 2012/ DISCUSSION... AVIATION UPDATE. AVIATION... SET UP TODAY SIMILAR TO YESTERDAY...WITH MOISTURE STREAMING IN OFF THE GULF. SHOULD AGAIN BE UNCAPPED AND UNSTABLE THIS AFTERNOON WITH SCATTERED STORMS DEVELOPING A LITTLE INLAND FROM THE COAST...ALONG WEAK SEA BREEZE CONVERGENCE. NOT MUCH ELSE TO ORGANIZE THE CONVECTION AS UPPER LOW CONTINUES TO DRIFT WEST...AND THINK COVERAGE MAY BE A LITTLE GREATER WEST OF THE TAF SITES BECAUSE OF THIS. BASED ON THIS HAVE GONE WITH THUNDER IN VICINITY FOR HOUSTON AREA TAF SITES AND ALSO CLL THIS AFTERNOON...AND LEFT ANY MENTION OF THUNDER OUT OF UTS. NOT CONFIDENT ENOUGH TO GO TEMPO ANYWHERE AS COVERAGE SHOULD BE LESS THAN PREVIOUS DAYS AND CANT PINPOINT EXACTLY WHERE THE STORMS WILL FORM. WILL NEED TO WATCH RADAR TRENDS THIS MORNING TO SEE IF AN UPDATE MAY BE NEEDED. 46 PREV DISCUSSION... /ISSUED 409 AM CDT TUE JUL 17 2012/ DISCUSSION... RADAR IS DETECTING SOME SMALL LOW TOPPED SHOWERS IN THE COASTAL WATERS AND IN MATAGORDA AND BRAZORIA COUNTIES AT 0845Z BUT COVERAGE IS MUCH LESS THAN THIS TIME LAST NIGHT BASED UPON 24HR RADAR LOOP. TODAY LOOKING LIKE A SLIGHTLY LESS RAINY VERSION OF YESTERDAY. GFS AND NAM TIME SECTIONS SHOW PWAT VALUES DROPPING QUITE A BIT STARTING THIS TUESDAY EVENING (NEARLY A HALF INCH LOWER). AS A RESULT SHOWER AND THUNDERSTORM CHANCES DROP TO THE SLIGHT EXCEPT FOR SOME INLAND AREAS DUE TO SCATTERED SEA BREEZE STORMS MAINLY IN THE AFTERNOON...IN GENERAL THOUGH THE TREND IS FOR LESS AND LESS RAIN AS THE WEEK CONTINUES...MAY BE A BIT HIGH ON THURSDAY PRECIP CHANCES IN THE AFTERNOON. LITTLE CHANGE TO PREVIOUS FORECASTS. DID ADJUST MAX TEMPERATURES UP IN THE NORTHWESTERN COUNTIES...KCLL IN PARTICULAR AS 94F WAS REACHED YESTERDAY. ECMWF EXPERIMENTAL MOS IS WARMER THAN BOTH NAM/GFS MOS FOR KCLL AND LEANED TOWARDS ECM AND PERSISTENCE. ELSEWHERE STATUS QUO FROM PREVIOUS FORECAST. NAM/ECM/GFS MOS AND PERSISTENCE ALL 91F AGAIN TODAY FOR KIAH...CANNOT ARGUE WITH THAT. CURRENT FORECAST IS SLIGHTLY HIGHER THAN GFS MOS GUIDANCE FOR THE LATE PART OF THE WEEK INTO THE WEEKEND. THIS TREND CONTINUES TO LOOK GOOD WITH LARGE RIDGE BUILDING NORTH OF THE CWA AND ECM MOS/GFS ENSEMBLE MOS ARE IN AGREEMENT WITH OUR OUTLOOK. CAN SEE EVEN SOME WARMER TEMPS THAN FORECAST POSSIBLE ON SATURDAY IF DRY SOUTH/SOUTHWESTERLY SFC-700MB FLOW OCCURS PER GFS. SOME 100 TO 105 HEAT INDICES POSSIBLE INLAND DURING THE MID TO LATE AFTERNOON HOURS THE NEXT FEW DAYS. DID DROP DEW POINT TEMPS FROM PREVIOUS IN THE MID AFTERNOON HOURS FOR FAR W/NW PART OF CWA PER OBSERVED TRENDS. 04 MARINE... MOSTLY LIGHT SOUTH TO SOUTHEAST FLOW WILL PERSIST THROUGHOUT MUCH OF THE WEEK...GIVEN FLOW AROUND SURFACE HIGH CENTERED OVER SE UNITED STATES. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE FROM TIME TO TIME WITH WINDS AND SEAS LOCALLY HIGHER IN AND NEAR THE STORMS. 46 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 74 94 73 95 74 / 20 20 10 20 10 HOUSTON (IAH) 76 93 76 93 75 / 10 30 10 30 10 GALVESTON (GLS) 81 90 81 91 81 / 20 20 10 20 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && DISCUSSION...45 AVIATION/MARINE...38
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 706 AM CDT TUE JUL 17 2012 TXZ163-164-176>179-195>200-210>214-226-227-235>238-181215- AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND- GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA- MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON- WHARTON- 706 AM CDT TUE JUL 17 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS. .DAY ONE...TODAY AND TONIGHT ISOLATED SHOWERS AND THUNDERSTORMS WILL MOVE ASHORE THIS EARLY THIS MORNING. AS TEMPERATURES RISE INTO THE MID 80S SHOWERS AND THUNDERSTORMS WILL INCREASE IN CONVERAGE AND BECOME SCATTERED ACROSS SOUTHEAST TEXAS GRADUALLY SPREADING FURTHER INLAND. RAINFALL AMOUNTS WILL AVERAGE BETWEEN 0.25 AND 0.75 INCHES WITH SOME 1.0 TO 1.5 INCH TOTALS IN THE STRONGER STORMS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE WEDNESDAY AND THURSDAY. HEAT INDEX VALUES WILL BEGIN TO INCREASE ON FRIDAY WITH HEAT INDEX VALUES BETWEEN 102 AND 106 DEGREES OVER PARTS OF THE AREA ON SATURDAY AND SUNDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
254 PM CDT TUE JUL 17 2012
TXZ199-213-172045-
HARRIS TX-MONTGOMERY TX-
254 PM CDT TUE JUL 17 2012
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN HARRIS AND
SOUTHEASTERN MONTGOMERY COUNTIES UNTIL 345 PM CDT...
AT 251 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS
TRACKING A LINE OF STRONG THUNDERSTORMS ALONG A LINE EXTENDING
FROM CLOVERLEAF TO GALENA PARK TO SOUTH HOUSTON...AND MOVING NORTH
AT 15 MPH.
HAIL UP TO THE SIZE OF PEAS AND WIND GUSTS UP TO 40 MPH WILL BE
POSSIBLE WITH THESE STORMS.
LOCATIONS IMPACTED INCLUDE...
HOUSTON...SPRING...THE WOODLANDS...CLOVERLEAF...HUMBLE...SOUTH
HOUSTON...ALDINE...GALENA PARK...JACINTO CITY...OAK RIDGE NORTH...
SHENANDOAH...PORTER HEIGHTS AND CHATEAU WOODS.
LAT...LON 2967 9518 2960 9535 2990 9550 3014 9554
3026 9532 2984 9515
TIME...MOT...LOC 1951Z 168DEG 12KT 2984 9524 2975 9522 2970 9530
!KP!The Houston radar (KHGX), 90 km away, was scanning. The volume nearest the first event began at 20:19 UTC.
5 lightning, 1 thunderstorm wind. Local standard time, as filed.
A two-story home was struck by lightning at 3 Golden Thrush Place and a fire was reported in the attic and roof. Lightning plot and radar imagery indicate the strike causing the fire could've occurred any time between 2-305 pm CST.
A detached garage was struck by lightning and destroyed by a fire at 19 West Willowood Court in the Woodlands. Time estimation by radar and lightning plot indicate the strike could've happened any time between 2-305 pm CST.
A building fire was caused by a lightning strike at 26 Sawmill Grove Place in the Woodlands. Time estimation via the radar and lightning plot show the strike could've occurred any time between 2-305 pm CST.
Lightning struck a house and caused a two alarm fire at 7 Acadia Place in Spring. Time estimation via radar and lightning plots shows the lightning strike could've occurred any time between 14-1505 CST.
There are reports of four separate house fires being started due to lightning. One has been confirmed via a picture on twitter. The time estimated from radar and a lightning plot is between 14-1505 CST.
Trees were blown down at the corner of Woodlands Parkway and Panther Creek.
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, July 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: 403870, 404378, 404381, 404395, 404402, 403873.