Isolated storms developed along outflow boundary that was sinking south across forecast area. A few of the storms produced damaging winds.
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 LSX wrote it up.
Isolated storms developed along outflow boundary that was sinking south across forecast area. A few of the storms produced damaging winds.
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 St. Louis, MO wrote its last area forecast discussion before the first event at Aug 12, 2:53 PM CST, 27 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 353 PM CDT FRI AUG 12 2011 .DISCUSSION... /346 PM CDT FRI AUG 12 2011/ CURRENT SHOWERS/STORMS ON RADAR ASSOCIATED WITH VORT MAX...MCV OVER N CNTRL MO. THIS CONVECTION WILL MOVE THROUGH MAINLY THE SRN AND ERN PORTION OF OUR FORECAST AREA EARLY THIS EVNG. A LOT OF UNCERTAINTY WITH REGARDS TO ADDITIONAL CONVECTION FOR LATER TGT AND IT IS BEGINNING TO LOOK LIKE MOST OF THE ACTIVITY WILL BE ACROSS SRN MO AS MAIN OUTFLOW BOUNDARY PUSHES FURTHER S. STRONG SHORTWAVE OVER ND WILL DROP SEWD INTO THE GREAT LAKES REGION ON SAT. THIS FEATURE WILL SEND A CDFNT SEWD THROUGH OUR AREA. MODELS ARE A LITTLE SLOWER WITH THE SEWD PROGRESSION OF THIS FRONT... ESPECIALLY THE NAM WHICH LOOKS TOO SLOW. WILL PUT THE HIGHEST POPS OVER THE ERN AND SRN PORTIONS OF OUR AREA TGT AND OVER THE ERN PORTION ON SAT. THE LATEST 4 KM NCEP WRF WAS A LITTLE SLOW WITH THE CURRENT CONVECTION BUT MOVES IT THROUGH OUR AREA THIS EVNG WITH LITTLE PRECIPITATION FOR LATE TGT AND SAT MRNG...THEN A LINE OF CONVECTION MOVING SEWD THROUGH IL SAT AFTN JUST EAST OF THE MISSISSIPPI RIVER ALONG THE CDFNT AND AHEAD OF A SHORTWAVE TROUGH. THIS APPEARS REASONABLE ALTHOUGH COULD NOT RULE OUT WIDELY SCATTERED TO SCATTERED CONVECTION LATER TGT INTO SAT MRNG. WITH SLOWER MOVEMENT OF THE CDFNT TEMPERATURES OVER ALL BUT THE NRN OR NWRN PORTION OF THE AREA SHOULD BE QUITE WARM ON SAT...THEN COOLER AND LESS HUMID AIR WILL FILTER INTO OUR AREA SAT NGT BEHIND THE CDFNT AND AS THE UPPER LEVEL TROUGH DEEPENS OVER THE GREAT LAKES REGION. COULD STILL HAVE LINGERING SHOWERS OVER THE ERN PORTION OF OUR FORECAST AREA INTO SAT EVNG BUT THEN A COOL AND DRY PERIOD FOR THE REST OF THE WEEKEND INTO EARLY NEXT WEEK AS A SFC RIDGE MOVES SLOWLY EWD THROUGH THE REGION. MAY GET WAA PRECIPITATION AS EARLY AS LATE MON NGT INTO TUE AS THE SFC RIDGE MOVES EAST OF OUR AREA. A BETTER CHANCE OF RAIN LIKELY LATER IN THE WEEK WED NGT AND THU AS ANOTHER CDFNT IS FORECAT TO MOVE THROUGH THE AREA. GKS && .AVIATION... /1156 AM CDT FRI AUG 12 2011/ DECAYING NOCTURNAL MCS AND ASSOCIATED OUTFLOW MOVING TOWARD CENTRAL MISSOURI WITH AREA OF SCATTERED SHOWERS AND THUNDERSTORMS DEVLEOPING AHEAD OF THE SYSTEM IN WEAK WARM ADVECTION REGIME. EXPECT SCT SHOWERS AND STORMS AROUND THIS AFTERNOON...WITH REDEVELOPMENT OF THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS SOUTHERN MISSOURI ALONG OUTFLOW BOUNDARY. COLD FRONT WILL MOVE ACROSS THE AREA LATE TONIGHT WITH WINDS SHIFTING TO THE WEST AND NORTHWEST ON FRIDAY. SPECIFICS FOR KSTL... SCATTERED SHOWERS AND THUNDERSTORMS WILL BE AROUND THIS AFTERNOON AS REMNANTS OF NOCTURNAL MCS CONTINUES TO DISSIPATE. OTHERWISE...NEW THUNDERSTORM DEVELOPMENT WILL LIKELY OCCUR TO THE SOUTH ALONG THE OUTFLOW BOUNDARY FROM THIS MORNINGS CONVECTION. BELIEVE THESE STORMS MAY TRACK ACROSS SOUTHERN MISSOURI...WITH ONLY STRATIFORM RAIN AND ISOLATED THUNDER AFFECTING TERMINAL OVERNIGHT. WIND TO VEER FROM SOUTH TO WEST BEHIND COLD FRONTAL PASSAGE OVERNIGHT. CVKING && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && WFO LSX
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE ST LOUIS MO 411 PM CDT FRI AUG 12 2011 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-131130- GREENE IL-MACOUPIN IL-MONTGOMERY IL-BOND IL-FAYETTE IL-CLINTON IL- MARION IL-WASHINGTON IL-RANDOLPH IL-ADAMS IL-BROWN IL-PIKE IL- CALHOUN IL-JERSEY IL-MADISON IL-ST. CLAIR IL-MONROE IL-KNOX MO- LEWIS MO-SHELBY MO-MARION MO-MONROE MO-RALLS MO-PIKE MO-BOONE MO- AUDRAIN MO-MONITEAU MO-COLE MO-OSAGE MO-CALLAWAY MO-MONTGOMERY MO- LINCOLN MO-GASCONADE MO-WARREN MO-ST. CHARLES MO-FRANKLIN MO- ST. LOUIS MO-ST. LOUIS CITY MO-JEFFERSON MO-CRAWFORD MO- WASHINGTON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO-IRON MO- MADISON MO-REYNOLDS MO- 411 PM CDT FRI AUG 12 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND CENTRAL MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS. .DAY ONE...TONIGHT THERE IS A CHANCE OF THUNDERSTORMS TONIGHT. SOME OF THE STORMS MAY BE SEVERE ACROSS PORTIONS OF CENTRAL AND SOUTHEAST MISSOURI AS WELL AS SOUTHWEST ILLINOIS . THE MAIN SEVERE WEATHER THREAT WILL BE DAMAGING WINDS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THERE REMAINS A CHANCE OF THUNDERSTORMS ON SATURDAY AS A COLD FRONT MOVES THROUGH THE AREA. SOME OF THE STORMS ACROSS EAST CENTRAL AND SOUTHEAST MISSOURI AS WELL AS SOUTHWEST ILLINOIS MAY BE SEVERE. THE MAIN SEVERE WEATHER THREAT WILL BE DAMAGING WINDS AND LARGE HAIL. THERE IS ANOTHER CHANCE OF THUNDERSTORMS WEDNESDAY NIGHT AND THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS POSSIBLE TONIGHT. GKS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE ST LOUIS MO 354 PM CDT FRI AUG 12 2011 MOZ072-073-122145- CRAWFORD MO-WASHINGTON MO- 354 PM CDT FRI AUG 12 2011 ...SIGNIFICANT WEATHER ADVISORY FOR WESTERN WASHINGTON AND NORTHERN CRAWFORD COUNTIES UNTIL 445 PM CDT... AT 346 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR LEASBURG...OR NEAR CUBA...MOVING EAST AT 30 MPH. HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... ANTHONIES MILL... RICHWOODS... ST. CLOUD... SHIRLEY... LATTY... CVKING
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
400 PM CDT FRI AUG 12 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM HAIL BOURBON 38.15N 91.25W
08/12/2011 E0.25 INCH CRAWFORD MO TRAINED SPOTTER
&&
JPThe St Louis radar (KLSX), 94 km away, was scanning. The volume nearest the first event began at 21:20 UTC.
5 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds blew down a few power lines and tree limbs.
Thunderstorm winds blew down several large tree limbs around Belgrade.
Thunderstorm winds blew down numerous large tree limbs.
Thunderstorm winds blew down numerous large tree limbs around Lake Killarney.
Thunderstorm winds blew down several large trees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Missouri in 2011Every state in 2011This day in weather historyWarnings in Missouri, August 2011
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: 341997, 341998, 342001, 342003, 342004.