Scattered thunderstorms developed along a nearly stationary frontal boundary during the early morning hours of July 29th. One of the thunderstorm cells produced wind damage across southern Knox County into far western Peoria County before dissipating as it tracked further eastward.
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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 ILX wrote it up.
Scattered thunderstorms developed along a nearly stationary frontal boundary during the early morning hours of July 29th. One of the thunderstorm cells produced wind damage across southern Knox County into far western Peoria County before dissipating as it tracked further eastward.
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 Lincoln, IL wrote its last area forecast discussion before the first event at Jul 29, 2:33 AM CST, 2 hours 43 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 333 AM CDT FRI JUL 29 2011 .DISCUSSION... ISSUED 313 AM CDT FRI JUL 29 2011 UPPER HIGH DOMINATING SOUTHEASTERN CONUS WHILE THE MORE ZONAL AND RAPID FLOW CROSSES THE NRN TIER OF THE COUNTRY...LEAVING ILX JUST ON THE EDGE OF THE MORE PROGRESSIVE PATTERN. A WEAK FRONTAL BOUNDARY STRETCHING FROM THE SRN PLAINS UP INTO THE GREAT LAKES PROVIDING FOCUS FOR MORNING SHOWERS AND CONVECTION. WHILE SRN END OF LK MI AND NORTHERN MO BOTH HAVE AREAS OF PRECIP...THE BOUNDARY IN THE MIDDLE ACROSS ILLINOIS REMAINS DRY...FOR NOW. CONVERGENCE IS MINIMAL AND THERE IS LITTLE UPPER AIR FORCING TO PUSH THE DEVELOPMENT. THAT BEING SAID...WAVE TO THE SW SHOULD HELP NUDGE THE BOUNDARY SLOWLY SWD BEFORE IT FALLS APART LATER IN THE WEEKEND...AND THIS WILL BE THE FIRST MAIN ISSUE FOR THE FORECAST. BEYOND THAT...THE HEAT MAKES A SLOW RETURN IN ADVANCE OF NEXT MAJOR SYSTEM LATE TUES INTO WED. SHORT TERM...TODAY AND TONIGHT... SCT TS CHANCES THROUGH TONIGHT FOR MUCH OF CENTRAL ILLINOIS AS THE SYNOPTIC PUSH FOR THE FRONTAL BOUNDARY IS SKETCHY AT BEST. MODELS SEEM TO BE PARTIALLY DEPENDENT ON A STRONG COLD POOL DEVELOPMENT WITH WAVES TO THE SW. WAVES DO NOT SEEM PARTICULARLY AGGRESSIVE AT THE MOMENT...BUT IT IS IN THE OVERNIGHT...NOT THE PEAK HEATING. SO WILL KEEP THE MOD CHANCE POP IN AND LEAVE IT RATHER EXPANSIVE THROUGHOUT THE DAY TO COVER ANY UNCERTAINTY IN TIMING. CHANCE POPS NOT REALLY CLEARING OUT UNTIL VERY EARLY IN THE MORNING ON SAT AS THE POPS SHOULD SHIFT SOUTHWARD. LONG TERM...SATURDAY THROUGH TUESDAY... POPS GET CONFINED TO THE SOUTH...ALONG AND SOUTH OF INTERSTATE 70 SATURDAY MORNING AS THE BOUNDARY LOSES WHAT CONVERGENCE IT HAS AND DISSIPATES TO THE SOUTH. CONCERN WILL BE THAT THE BOUNDARY DOES NOT TIME OUT THE WAY THE MODELS ARE SAYING WITH A WEAKER BAROCLINIC ZONE...AND MAY NOT PUSH AS FAR SOUTH AND PROVIDE A SET UP FOR SOME MORE PRECIP INTO SAT EVENING. FOR NOW...WILL KEEP IT RELATIVELY DRY. HEAT RETURNS...AND WHEREAS MODELS DRY TO DEVELOP PRECIP ALONG A WEAK FRONT ON SUN NIGHT...WILL OPT TO LEAVE OUT POPS AS THE CONVERGENCE IS MINIMAL IN A RELATIVELY DRY LAYER. HOWEVER...HEAT REALLY KICKS IN ON OTHER SIDE OF IT. WITH TEMPS INCREASING THROUGH TUES...VERY VERY HOT ON TUESDAY AHEAD OF APPROACHING SYSTEM FOR TUES NIGHT...WITH HEAT INDICES APPROACHING 107F AS OF THIS FORECAST. DEPENDENT ON SYSTEM TIMING AND WAA...COULD BE SOME RATHER EXPLOSIVE CONVECTION WITH CAPES IN EXCESS OF 3000 J/KG AT 18Z...AND OVER 4500 J/KG AT 00Z THAT EVENING. LAPSE RATES ARE MINIMAL...BUT IN WEAK NWRLY FLOW ALOFT. HJS && .AVIATION... ISSUED 1100 PM CDT THU JUL 28 2011 MAIN FORECAST CHALLENGE THIS EVENING CONTINUES TO BE COVERAGE OF CONVECTION AHEAD OF COLD FRONT...CURRENTLY OVER EAST CENTRAL IOWA. A SECONDARY CONCERN WILL BE WITH MVFR VSBYS IN FOG TOWARDS MRNG JUST AHEAD OF THE COOL FRONT. CONVECTION FINALLY STARTING TO FIRE ALONG THE WEAK COOL FRONT TO OUR WEST BUT COVERAGE IS STILL NOT THAT GREAT AT THIS TIME. BASED ON CURRENT MOVEMENT...IT APPEARS PIA AND BMI WOULD HAVE THE BETTER CHANCES OF SEEING A PERIOD OF MVFR VSBYS IN TSRA LATER THIS EVENING AND DURING THE OVERNIGHT HOURS. FURTHER SOUTH...STILL QUITE A BIT OF UNCERTAINTY TO HOW FAR EAST AND SOUTH THE CONVECTION WILL GO...SO UNTIL WE SEE A CONSISTENT TREND IN THAT AREA...WILL CONTINUE TO COVER WITH VCTS. LIGHT WINDS AND ABUNDANT LOW LEVEL MOISTURE SHOULD BRING ABOUT A PERIOD OF LIGHT FOG JUST BEFORE DAWN SO WILL CONTINUE FROM PREVIOUS FORECAST AND INCLUDE 3-5SM VSBYS IN FOG. FRONT SHOULD GRADUALLY SHIFT FROM NORTHWEST TO SOUTHEAST ACRS THE FORECAST AREA FRIDAY MORNING WITH WDLY SCATTERED CONVECTION ALONG AND JUST AHEAD OF THE BOUNDARY. FOR NOW WILL CONTINUE WITH VCTS AS COVERAGE LATER TOMORROW MORNING INTO THE AFTERNOON HOURS VERY UNCERTAIN THIS FAR OUT. FRONT SHOULD CLEAR OUT SOUTHERN TAF SITES BY MID AFTN WITH SFC WINDS SHIFTING FROM THE SOUTHWEST INTO THE NORTHWEST...BUT SPEEDS WILL CONTINUE TO BE ON THE LIGHT SIDE...GENERALLY 10 KTS OR LESS. SMITH && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LINCOLN IL 610 AM CDT FRI JUL 29 2011 ILZ027>031-036>038-301100- FULTON-KNOX-MARSHALL-MCLEAN-PEORIA-STARK-TAZEWELL-WOODFORD- 610 AM CDT FRI JUL 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS. .DAY ONE...TODAY AND TONIGHT A WEAK COLD FRONT WILL MOVE THROUGH THE AREA TODAY BRINGING SCATTERED THUNDERSTORMS...ESPECIALLY THIS MORNING. NO ORGANIZED SEVERE STORM THREAT IS EXPECTED...HOWEVER SOME OF THE STRONGER STORMS MAY PRODUCE GUSTY WINDS AND INTENSE LIGHTNING. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY HOT AND HUMID WEATHER WILL BE COMMON THROUGH THE MIDDLE OF NEXT WEEK...WITH THE HOTTEST DAY EXPECTED TO BE TUESDAY. HIGHS WILL BE IN THE LOWER 90S WITH HEAT INDEX VALUES 95 TO 105. A COLD FRONT WILL ENTER THE AREA AND BRING THE NEXT THREAT OF THUNDERSTORMS TO THE AREA LATE TUESDAY INTO LATE WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. ILZ040>057-061-301100- CASS-CHAMPAIGN-CHRISTIAN-COLES-DE WITT-DOUGLAS-EDGAR-LOGAN-MACON- MASON-MENARD-MORGAN-MOULTRIE-PIATT-SANGAMON-SCHUYLER-SCOTT-SHELBY- VERMILION- 610 AM CDT FRI JUL 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS AND EAST CENTRAL ILLINOIS. .DAY ONE...TODAY AND TONIGHT A WEAK COLD FRONT WILL MOVE THROUGH THE AREA TODAY BRINGING SCATTERED THUNDERSTORMS...ESPECIALLY FROM MIDDAY INTO EARLY EVENING. NO ORGANIZED SEVERE STORM THREAT IS EXPECTED...HOWEVER SOME OF THE STRONGER STORMS MAY PRODUCE GUSTY WINDS AND INTENSE LIGHTNING. HOT AND HUMID CONDITIONS CAN BE EXPECTED TODAY...WITH HIGHS AROUND 90 AND HEAT INDEX VALUES FROM 95 TO 100. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY HOT AND HUMID WEATHER WILL BE COMMON THROUGH THE MIDDLE OF NEXT WEEK...WITH THE HOTTEST DAY EXPECTED TO BE TUESDAY. HIGHS WILL BE IN THE LOWER 90S WITH HEAT INDEX VALUES 95 TO 105. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. ILZ062-063-066>068-071>073-301100- CLARK-CLAY-CRAWFORD-CUMBERLAND-EFFINGHAM-JASPER-LAWRENCE-RICHLAND- 610 AM CDT FRI JUL 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL ILLINOIS AND SOUTHEAST ILLINOIS. .DAY ONE...TODAY AND TONIGHT A WEAK COLD FRONT WILL MOVE THROUGH THE AREA LATE TODAY BRINGING SCATTERED THUNDERSTORMS...ESPECIALLY THIS EVENING AND OVERNIGHT. NO ORGANIZED SEVERE STORM THREAT IS EXPECTED...HOWEVER SOME OF THE STRONGER STORMS MAY PRODUCE GUSTY WINDS AND INTENSE LIGHTNING. HOT AND HUMID CONDITIONS CAN BE EXPECTED TODAY...WITH HIGHS AROUND 90 AND HEAT INDEX VALUES FROM 95 TO 100. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THERE WILL BE A CHANCE FOR THUNDERSTORMS ON SATURDAY...BUT NO SEVERE WEATHER IS ANTICIPATED. HOT AND HUMID WEATHER WILL BE COMMON THROUGH THE MIDDLE OF NEXT WEEK...WITH THE HOTTEST DAY EXPECTED TO BE TUESDAY. HIGHS WILL BE IN THE LOWER 90S WITH HEAT INDEX VALUES 95 TO 105. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.
The Quad Cities radar (KDVN), 90 km away, was scanning. The volume nearest the first event began at 11:16 UTC.
3 thunderstorm wind. Local standard time, as filed.
Numerous large tree limbs were blown down just north of Abingdon.
Numerous corn fields were flattened around Yates City.
Trees were blown down across Route 8 in Elmwood.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2011Every state in 2011This day in weather historyWarnings in Illinois, July 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: 333459, 333461, 333463.