Showers and thunderstorms developed during the afternoon in and around the League City area of northern Galveston County. Activity continued to develop and train across the same areas for several hours resulting in flash flooding.
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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.
Showers and thunderstorms developed during the afternoon in and around the League City area of northern Galveston County. Activity continued to develop and train across the same areas for several hours resulting in 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 Houston/Galveston, TX wrote its last area forecast discussion before the first event at Oct 1, 2:40 PM CST, 1 hour 9 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 340 PM CDT THU OCT 1 2009 .DISCUSSION... WARM ADVECTION HAS RESULTED IN SHOWER DEVELOPMENT UNDER THE CAP THIS AFTN. THE CONVECTION HAS BEEN TRAINING OVER THE OFFICE WHERE RADAR ESTIMATES 1-2 INCHES OF RAIN HAS FALLEN. THIS ISOLATED CONVECTION WILL PERSIST THROUGH THE EARLY EVENING HOURS. COLD FRONT EXTENDS FROM SAN ANGELO TO MINERAL WELLS THIS HOUR. THE FRONT IS EXPECTED TO REACH OUR NRN ZONES AROUND 1 AM THEN THE I-10 CORRIDOR JUST AFTER SUNRISE FRIDAY. 30 KT LOW LEVEL JET WILL RESULT IN A CONTINUED INCREASE IN MOISTURE LEVELS THIS EVENING WITH PWS REACHING AROUND 2 INCHES. NMM-WRF SOLUTION SHOWS A SOLID LINE OF CONVECTION DEVELOPING ALONG THE FRONT AS THE CAP BREAKS LATER THIS EVENING. GFS FORECASTS HELICITY VALUES OF >200 M2/S2 MAINLY OVER THE NRN ZONES FAVORING THE POTENTIAL FOR A FEW SEVERE STORMS. THE PRIMARY SEVERE WEATHER THREAT WILL BE DAMAGING STRAIGHT-LINE WINDS (GIVEN THE UNIDIRECTIONAL PROFILE). MARGINALLY SEVERE HAIL ALSO POSSIBLE THOUGH THE FREEZING LEVELS ARE QUITE HIGH. BAND OF CONVECTION WILL PERSIST OVER THE SRN HALF OF THE AREA EARLY FRIDAY UNTIL THE FRONT STALLS JUST OFF THE COAST BY LATE MORNING. CLEARING SKIES AND LOWER HUMIDITY LEVELS EXPECTED FRI AFTN/EVENING IN THE WAKE OF THE FRONT AS PWS DROP TO BELOW AN INCH MOST INLAND LOCATIONS. SFC FRONT WILL BEGIN TO SLOWLY RETURN NORTH AS A WARM FRONT LATE FRI NIGHT/SATURDAY AS A DEVELOPING TROUGH OVER THE WESTERN STATES INDUCES A LOW LEVEL SOUTHERLY FLOW. 30-40 KT LOW LEVEL JET DEVELOPS SATURDAY WHICH WILL RESULT IN A RAPID RETURN OF MOISTURE TO THE AREA. PWS ARE FORECAST TO INCREASE TO 2.0-2.3 INCHES ACROSS ALL OF SE TX BY 00Z SUNDAY. FLOW ALOFT BECOMES SOUTHWEST RESULTING IN A SERIES OF WEAK UPPER LEVEL DISTURBANCES CROSSING THE AREA. THESE DISTURBANCES WILL GENERATE LIFT WHILE THE SLOWLY RETREATING WARM FRONT PROVIDES A FOCUS FOR CONVECTIVE DEVELOPMENT. HAVE BLANKETED HIGH POPS (50S/60S) AREA WIDE SAT AFTN THROUGH SUNDAY. THE PRIMARY THREATS WITH THE STORMS WILL BE HEAVY RAINFALL AND CLOUD-TO-GROUND LIGHTNING. HPC QPF FCST HAS A BULLS-EYE OF 1.5-2.5 INCHES OF RAIN SATURDAY THROUGH SUNDAY ACROSS THE CWA...WITH LOCALLY HIGHER AMOUNTS EXPECTED. STRONG UPPER LOW WILL DIG SOUTH ACROSS NEVADA/CALIFORNIA EARLY NEXT WEEK. IN RESPONSE TO THIS...STRONG UPPER RIDGING WILL DEVELOP OVER THE GULF COAST REGION. MODELS FORECAST 500 MB HEIGHTS OF 591 DM OVER THE AREA BY TUESDAY/WEDNESDAY. COPIOUS AMOUNTS OF MOISTURE WILL REMAIN IN PLACE OVER SE TX THROUGH MIDWEEK WITH PWS OF 1.8-2.1 INCHES. HOWEVER...SUBSIDENCE WILL INCREASE UNDER THE STRENGTHENING RIDGE WHICH WILL RESULT IN LESS CONVECTIVE COVERAGE ESPECIALLY NEAR THE COAST. WILL MAINTAIN CHANCE POPS MONDAY THROUGH WEDNESDAY GIVEN THE ANTICIPATION OF SCATTERED CONVECTIVE DEVELOPMENT. MODELS FORECAST VERY HIGH 1000-500 MB THICKNESS VALUES (AROUND 580) AND HIGH SFC DEWPOINTS (75-80). TEMPS/HUMIDITY WILL BE AT MID SUMMER LEVELS WITH MINS BARELY DROPPING BELOW 80 AND AFTN HEAT INDICES TOPPING OUT AROUND 105 DEGREES. LATEST GFS/ENSEMBLE MEAN SHOW THE TROUGHING PHASING OVER THE PLAINS LATE WEEK WITH STRONG FRONT PUSHING SLOWLY THROUGH THE AREA THU/FRI. 12Z ECMWF RUN ALSO BRINGS FRONT INTO THE AREA LATE WEEK BUT SHOWS LIKELIHOOD OF IT STALLING AS TROUGHING PERSISTS OVER THE SOUTHWEST. 35 && .AVIATION... SMALLISH CLUSTER OF STORMS THAT DEVELOPED OVER THE AREA AROUND THE 18Z TAF TIME IS STARTING TO SLOWLY MOVE OUT TO THE EAST THIS AFTN. HOWEVER WE COULD STILL BE DEALING WITH CONVECTION IN THE AREA THIS EVENING AS THAT LINE OF (NOW WEAKENING) SHRA CONTINUES TO PUSH EWD FROM SC TX. THIS ALONG WITH THE PROGGED FROPA (AOA SUNRISE) SHOULD KEEP AT LEAST VCSH/VCTS IN OVERNIGHT. OTHERWISE...WILL LIKELY KEEP CIGS IN THE MVFR RANGE AND WINDS SLIGHTLY ELEVATED UNTIL THE FRONT ARRIVES. VFR CONDITIONS TO PREVAIL IN THE POST-FRONTAL REGIME. 41 && .MARINE... WHILE WINDS HAVE PICKED UP SOME THIS AFTERNOON...WE ARE STAYING BE- LOW SCEC LEVELS. AND WITH WINDS JUST ABOVE THE SFC IN THE 15-20 KT RANGE (AS PER HGX VWP) THIS TREND SHOULD CONTINUE AT LEAST FOR THE SHORT TERM. FOR TOMORROW STILL LOOKING FOR A WEAK COLD FRONT TO AP- PROACH THE COASTAL WATERS AND THEN STALL. THIS BOUNDARY PROGGED TO RETREAT NORTH ON SATURDAY WITH MODERATE TO STRONG ONSHORE WINDS RE- DEVELOPING BY SATURDAY NIGHT/SUNDAY. THE PERSISTENT SOUTHERLY FLOW (ALONG WITH A SERIES OF UPPER LEVEL DISTURBANCES) EXPECTED TO PREV- AIL THROUGH THE FIRST PART OF NEXT WEEK. 41 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 66 85 62 78 69 / 70 10 10 60 60 HOUSTON (IAH) 72 84 65 83 71 / 70 40 20 60 60 GALVESTON (GLS) 76 84 75 82 76 / 40 50 20 60 50 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && DISCUSSION...35 AVIATION/MARINE...41
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 350 PM CDT THU OCT 1 2009 TXZ163-164-176>179-195>200-210>213-021200- AUSTIN-BRAZOS-BURLESON-COLORADO-GRIMES-HARRIS-HOUSTON-LIBERTY- MADISON-MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER- WASHINGTON- 350 PM CDT THU OCT 1 2009 ...SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS EVENING AND OVERNIGHT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS. .DAY ONE...TONIGHT A COLD FRONT WILL APPROACH SOUTHEAST TEXAS THIS EVENING AND MOVE SLOWLY THROUGH THE AREA DURING THE OVERNIGHT HOURS. THE FRONT WILL COMBINE WITH DEEP TROPICAL MOISTURE TO GENERATE A BAND OF SHOWERS AND THUNDERSTORMS. THESE STORMS ARE EXPECTED TO BEGIN AFFECTING THE NORTHERN PORTIONS OF SOUTHEAST TEXAS AFTER 10 PM...REACHING THE INTERSTATE 10 CORRIDOR LATE TONIGHT. MODERATE SHEAR IN THE ATMOSPHERE WILL SUPPORT THE POTENTIAL FOR A FEW SEVERE STORMS NORTH OF THE I-10 CORRIDOR. THE MAIN THREAT AREA FOR SEVERE WEATHER WILL BE NORTH OF A LINE FROM COLUMBUS TO HOUSTON TO CLEVELAND. THE MAIN TIME FRAME WILL BE 10 PM THIS EVENING TO 5 AM FRIDAY. THE PRIMARY SEVERE WEATHER THREATS WILL BE DAMAGING STRAIGHT-LINE WINDS AND MARGINALLY SEVERE HAIL. .DAYS TWO THROUGH FOUR...FRIDAY THROUGH SUNDAY AFTER A BREAK ON FRIDAY...THUNDERSTORM ACTIVITY IS EXPECTED TO CONTINUE OVER THE WEEKEND AS THE FRONT STALLS ALONG THE UPPER TEXAS COAST. THE THUNDERSTORM ACTIVITY SHOULD REMAIN BELOW SEVERE LIMITS BUT WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE...HEAVY RAINFALL WILL BE POSSIBLE OVER THE WEEKEND. MOST AREAS WILL LIKELY RECEIVE 1 TO 2 INCHES OF RAINFALL BUT LOCALIZED AMOUNTS CLOSER TO 2 TO 4 INCHES MAY BE POSSIBLE WITH STRONGER STORMS THAT TRAIN ACROSS THE SAME AREA. .DAYS FIVE THROUGH SEVEN...MONDAY THROUGH WEDNESDAY HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED TONIGHT. TXZ214-226-227-235>238-021200- BRAZORIA-CHAMBERS-FORT BEND-GALVESTON-JACKSON-MATAGORDA-WHARTON- 350 PM CDT THU OCT 1 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS. .DAY ONE...TONIGHT A COLD FRONT AND AN ASSOCIATED BAND OF SHOWERS AND THUNDERSTORMS WILL REACH THE AREA LATE TONIGHT. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING GUSTY WINDS...DANGEROUS LIGHTNING...AND BRIEF HEAVY RAINFALL. .DAYS TWO THROUGH FOUR...FRIDAY THROUGH SUNDAY THUNDERSTORMS WILL COME TO AN END FRIDAY MORNING. AFTER A BREAK ON FRIDAY...THUNDERSTORM ACTIVITY IS EXPECTED TO CONTINUE OVER THE WEEKEND AS THE FRONT STALLS ALONG THE UPPER TEXAS COAST. THE THUNDERSTORM ACTIVITY SHOULD REMAIN BELOW SEVERE LIMITS BUT WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE...HEAVY RAINFALL WILL BE POSSIBLE OVER THE WEEKEND. MOST AREAS WILL LIKELY RECEIVE 1 TO 2 INCHES OF RAINFALL BUT LOCALIZED AMOUNTS CLOSER TO 2 TO 4 INCHES MAY BE POSSIBLE WITH STRONGER STORMS THAT TRAIN ACROSS THE SAME AREA. .DAYS FIVE THROUGH SEVEN...MONDAY THROUGH WEDNESDAY HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED.
The Houston radar (KHGX), 5 km away, was scanning. The volume nearest the first event began at 21:47 UTC.
1 flash flood. Local standard time, as filed.
Repeated thunderstorm development and associated training across the far northern portions of Galveston County around the League City area produce flash flooding. Numerous roads were under water and several automobiles were flooded and abandoned.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Texas in 2009Every state in 2009This day in weather historyWarnings in Texas, October 2009
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: 192009.