Scattered storms developed and moved southeast across the 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.
Scattered storms developed and moved southeast across the 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 18, 11:11 PM CST, 1 hour 24 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED AVIATION NATIONAL WEATHER SERVICE ST LOUIS MO 1211 AM CDT FRI AUG 19 2011 .UPDATE... /856 PM CDT THU AUG 18 2011/ LEADING STRATIFORM PCPN REGION HAS DEVELOPED AHEAD OF THE STRONGER CONVECTIVE CORES IN NWRN MO/SWRN IA. SEVERAL ASOS SITES IN SRN IA HAVE ALREADY REPORTED MEASURABLE RAINFALL AND THE MID-LEVEL FLOW WILL CONTINUE TO SPREAD THIS PCPN INTO THE CWA TONIGHT. INCREASING LLJ SHOULD HELP TO MAINTAIN THE CONVECTION OVER NRN MO AS IT SINKS SWD OVERNIGHT. H85 THETA-E GRADIENT SHOULD ALSO SHIFT SLIGHTLY EWD WITH TIME AS THE SHORTWAVE APPROACHES. AS THE H85 GRADIENT SHIFTS EWD AND THE LLJ INCREASES /ESPECIALLY AFTER 09Z/...PCPN SHOULD ALSO SPREAD SEWD WITH TIME. UPDATED GRIDS AND PRODUCTS WILL BE SENT SHORTLY. KANOFSKY && .DISCUSSION... /303 PM CDT THU AUG 18 2011/ FOCUS FOR THE SHORT TERM WILL CONTINUE TO BE PRECIP CHANCES. FORECASTING MCS TRACKS CAN BE CHALLENGING...AND TONIGHT IS NO DIFFERENT. A WEAK WRMFNT EXTENDS FROM ERN NEB SWD INTO ERN KS AND SRN MO. ISOD TSRA WILL BE POSS ACROSS SERN MO EARLY THIS EVENING AS CONVECTION CONTINUES BEFORE SUNSET. BELIEVE ONGOING TSRA ACROSS ERN NEB AND WRN IA REGION WILL CONTINUE TO DEVELOP AND SINK SWD ACROSS WRN MO TONIGHT NEAR/ALONG THIS WRMFNT. THE LOCAL WRF/GFS/ECMWF AND TO SOME DEGREE THE NAM ALL AGREE RELATIVELY WELL WITH THE ABOVE SOLN. TSRA SHUD SINK SWD ALONG INSTABILITY GRADIENT...HOWEVER ANOTHER AREA OF TSRA IS EXPECTED ACROSS WRN AND NRN PORTIONS OF THE CWA ASSOCIATED WITH THE S/W AS IT DROPS SEWD. THIS S/W SHUD HELP SPREAD PRECIP ACROSS MUCH OF THE CWA DURING THE DAY FRI ALONG AND JUST AHEAD OF THE SFC LOW...SIMILAR TO WHAT IS ONGOING ACROSS ERN NEB. AFTER A BRIEF LULL FRI NIGHT...ANOTHER ROUND OF PRECIP IS ANTICIPATED THRU MUCH OF THE WEEKEND AS A TROF AND WEAK SFC WAVE MOVE THRU THE REGION. PRECIP SHUD COME TO AN END FROM NW TO SE DURING THE DAY SUN. AS FOR TEMPS IN THE SHORT TERM...WITH PRECIP EXPECTED EARLY IN THE DAY FRI...HAVE TRENDED TWD THE COOLER GUIDANCE EXPECTING CLOUD COVER. HOWEVER...ENUF BREAKS ARE STILL EXPECTED TO KEEP TEMPS IN THE UPPER 80S AND LOWER 90S. A BRIEF WARM UP IS POSS ON SAT AS A WEAK WRMFNT LIFTS NWD AGAIN...BUT COOLER TEMPS SHUD MOVE IN WITH THE SFC RIDGE FOR SUN. FOR THE EXTD...MDLS CONTINUE TO CHANGE TIMING OF SFC FEATURES FROM ONE RUN TO THE NEXT. THEREFORE...HAVE LOW CONFIDENCE IN ANY ONE MDL SOLN...ESP THE GFS WHICH SEEMS TO BE PLAGUED WITH CONVECTIVE FEEDBACK. WITH NW FLOW...CAN NOT COMPLETELY RULE PRECIP DURING THE EXTD...BUT KEPT HIGHER POPS WITH BEST CHANCES AND SLIGHT CHANCES THRU MUCH OF THE REST OF THE EXTD. FOR TEMPS IN THE EXTD...TRIED TO STAY WITH A PERSISTENCE FCST AS PRECIP ON ANY ONE DAY MAY KEEP TEMPS MUCH COOLER. KEPT EARLY NEXT WEEK COOLER AS MDLS PROG LOWER HEIGHTS...AND WARMED DURING THE WEEK. TILLY && .AVIATION... /1157 PM CDT THU AUG 18 2011/ MCS HAS PROGRESSED SO FAR ACCORDING TO PLAN...WITH STRONGEST ELEMENTS REMAINING TO OUR W AND CONTINUING TO DIVE SSE THRU WRN MO. THE REST WILL DRIVE MORE OF AN EWD ROUTE AS MCV SEPARATES ITSELF AND GOES MORE WITH THE MEAN MID LEVEL FLOW...WHICH WILL BE MORE OF A TRUE SE DIRECTION. THIS WILL SERVE TO PUSH THE LARGE AREA OF STRATIFORM RAIN WITH IMBEDDED TSRA THRU THE LIONS SHARE OF THE FA OVERNIGHT AND INTO FRIDAY MORNING. HAVE BEEFED UP TEMPO TSRA WORDING WITH HIGHER CONFIDENCE NOW THAT SOME THUNDER WILL OCCUR AT ALL TAF SITES. MAY SEE SOME MVFR CIGS DURING THE PEAK OF THE RAIN LATE TONIGHT AND FRIDAY MORNING AND THERE IS SOME HINT OF SOME BRIEF LO-MVFR TO IFR...BUT FOR NOW HAVE LEFT OUT. WITH CLEARING SKIES FRIDAY EVENING BEFORE THE NEXT ROUND OF CLOUDS HIT LATE THAT NIGHT...SHOULD SEE SOME MIST DEVELOP BY MIDNIGHT. SPECIFICS FOR KSTL...LOWERING AND THICKENING CIGS WILL BE THE RULE HEADING INTO LATE TONIGHT WITH SOME RA/TSRA ARRIVING AS EARLY AS 08-09Z WITH THE BULK HOLDING OFF UNTIL AFTER 12Z. SHOULD BE MAINLY RAIN BUT SOME THUNDER ALSO EXPECTED. ALSO EXPECT SOME LOWER NON- VFR CIGS FOR A PERIOD FRIDAY MORNING. IMPROVING CONDITIONS EXPECTED HEADING INTO FRIDAY AFTERNOON WITH VFR BY FRIDAY EVENING. MIST SHOULD HOLD OFF UNTIL LATE FRIDAY NIGHT...BUT COULD ALSO STAY AWAY AND REMAIN JUST IN VALLEY AREAS IN SURROUNDING AREAS. TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && WFO LSX
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE ST LOUIS MO 1257 AM CDT FRI AUG 19 2011 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-191115- 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- 1257 AM CDT FRI AUG 19 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND CENTRAL MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS. .DAY ONE...REST OF TONIGHT THUNDERSTORMS ARE LIKELY LATE TONIGHT ACROSS NORTHEASTERN AND CENTRAL MISSOURI AND WEST CENTRAL ILLINOIS WITH A CHANCE OF STORMS ACROSS SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS. SOME OF THE STORMS MAY BE STRONG TO SEVERE...CAPABLE OF PRODUCING HAIL AND STRONG WIND GUSTS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THERE IS A CHANCE FOR THUNDERSTORMS FRIDAY THROUGH SUNDAY. THERE IS ANOTHER CHANCE FOR THUNDERSTORMS ACROSS PORTIONS OF THE AREA ON TUESDAY AND WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT. GKS
The Pleasant Hill radar (KEAX), 130 km away, was scanning. The volume nearest the first event began at 06:33 UTC.
3 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds blew down several large tree limbs. A couple of the limbs pulled down power lines causing power outages around town.
A small tree was blown down onto Main Street in Linn.
Thunderstorm winds blew down several large tree limbs around town. A couple of the limbs pulled down power lines.
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: 342013, 342014, 342015.