An upper-level impulse in conjunction with a slow-moving cold front triggered scattered thunderstorms across central Illinois during the afternoon of August 17th. Despite modest instability, a few of the storms became severe and produced gusty 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 ILX wrote it up.
An upper-level impulse in conjunction with a slow-moving cold front triggered scattered thunderstorms across central Illinois during the afternoon of August 17th. Despite modest instability, a few of the storms became severe and produced gusty winds. One thunderstorm in Springfield produced a lightning strike which damaged a house.
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 Aug 17, 11:34 AM CST, 2 hours 12 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1234 PM CDT MON AUG 17 2009 .DISCUSSION... ISSUED 1012 AM CDT MON AUG 17 2009 FIRST BATCH OF RAIN HAS BEEN STEADILY DIMINISHING...AND IS LOCATED JUST EAST OF I-55. REGIONAL RADAR MOSAICS CONTINUE TO SHOW ANOTHER LARGE AREA OF SHOWERS AND THUNDERSTORMS ACROSS THE NORTHERN THIRD OF MISSOURI. MAIN CONCERN FOR TODAY INVOLVES RAIN CHANCES AND TEMPERATURES. LATEST VISIBLE SATELLITE IMAGERY SHOWING SOME BREAKS IN THE CLOUD COVER MOVING INTO WEST CENTRAL ILLINOIS. TEMPERATURES IN THE WESTERN CWA CURRENTLY ONLY IN THE LOWER 70S BUT HAVE THE POTENTIAL TO REBOUND QUICKLY IN THE SHORT TIME AVAILABLE BEFORE THE CLOUDS REDEVELOP. EARLY MODELS CONTINUE TO SHOW THE RAIN SHIELD IN MISSOURI PUSHING EASTWARD...ALBEIT IN A BIT OF A MORE WEAKENED STATE. MEANWHILE...CLEARING SKIES ACROSS THE SOUTHEAST CWA WILL LEAD TO MORE INSTABILITY IN THAT AREA...WITH THE NEW NAM BRINGING CAPES UP TO AROUND 2500 J/KG WITH LITTLE CIN BY MID AFTERNOON. OUTFLOW BOUNDARY FROM EARLIER RAIN AREA HAS ALREADY BEGUN TO FIRE SCATTERED CONVECTION ALONG A DANVILLE TO BELLEVILLE LINE. WILL MAKE NO CHANGES TO THE FLOOD WATCH AT THIS TIME...AS MORNING PRECIP REPORTS INDICATE 1 TO 3 INCHES OF RAIN HAS FALLEN WEST OF A GALESBURG TO SPRINGFIELD LINE. WILL NOT MAKE ANY CHANGES TO THE ZONES EITHER AT THE MOMENT...ALTHOUGH HOURLY GRID UPDATES HAVE ALREADY BEEN SENT. GEELHART && .AVIATION... ISSUED 1233 PM CDT MON AUG 17 2009 MAIN CONCERNS FOR THIS TAF PERIOD INVOLVE THE FIRST 6-9 HOURS OF THE FORECAST. AREA OF SHOWERS AND THUNDERSTORMS IN MISSOURI IS PUSHING EASTWARD...AHEAD OF A SLOW MOVING COLD FRONT. TRIED TO TIME THE MVFR CONDITIONS TO A 3-4 HOUR PERIOD DUE TO LOWER VISIBILITIES AND CEILINGS. BULK OF SHOWERS/STORMS SHOULD BE EAST OF THE TAF SITES BY 00Z...BUT WILL LINGER NEAR KCMI FOR A COUPLE MORE HOURS. AFTERWARD...HAVE SOME CONCERNS FOR MVFR VISIBILITIES OVERNIGHT AS WINDS BECOME LIGHT. POTENTIAL EXISTS FOR ANOTHER ROUND OF SHOWERS/STORMS TUESDAY MORNING...BUT THIS IS CURRENTLY FORECAST BY THE MODELS TO REMAIN JUST SOUTH OF THE TAF SITES. GEELHART && .PREV DISCUSSION... ISSUED 242 AM CDT MON AUG 17 2009 AN EXTENDED PERIOD OF WET WEATHER IS IN STORE ACROSS CENTRAL ILLINOIS...WITH DAILY RAIN CHANCES FROM TODAY THROUGH THURSDAY. 06Z SURFACE ANALYSIS SHOWS COLD FRONT EXTENDING FROM THE UPPER PENINSULA OF MICHIGAN SOUTHWESTWARD INTO EASTERN KANSAS. VERY MOIST AIRMASS IN PLACE AHEAD OF THE BOUNDARY...AS EVIDENCED BY DEWPOINTS AROUND 70 DEGREES AS FAR NORTH AS EASTERN WISCONSIN. MCS HAS DEVELOPED AHEAD OF THE FRONT ACROSS NORTHWEST ILLINOIS/NORTHERN MISSOURI AND IS BEGINNING TO PUSH E/NE INTO WEST-CENTRAL ILLINOIS. ALOFT...DEEP UPPER LOW IS SPINNING OVER SOUTHERN MANITOBA...WHILE BROAD SOUTHWESTERLY FLOW PREVAILS ACROSS THE PLAINS AND MIDWEST. SHORT TERM...TODAY THROUGH WEDNESDAY THUNDERSTORMS WILL CONTINUE TO BUILD ALONG NOSE OF 30KT LLJ EARLY THIS MORNING...THEN SLOWLY MOVE EASTWARD INTO CENTRAL ILLINOIS. LOCALLY HEAVY RAINFALL WILL BE LIKELY WITH THESE STORMS...ESPECIALLY ACROSS LOCATIONS WEST OF I-55. ADDITIONAL SHOWERS/STORMS WILL BLOSSOM AS THE DAY GOES ON...WITH POTENTIAL FOR SEVERE WEATHER DEVELOPING ALONG OUTFLOW BOUNDARY LEFT BEHIND BY MORNING CONVECTION. EXACT LOCATION OF THIS MESOSCALE BOUNDARY AND EXTENT OF DESTABILIZATION REMAIN IN QUESTION...HOWEVER HEAVY RAIN THREAT IS APPARENT. BASED ON RADAR TRENDS AND 00Z NAM-WRF OUTPUT...WILL INCREASE POPS TO CATEGORICAL ALONG AND NORTH OF I-72 TODAY...WITH LIKELY OR HIGH CHANCE POPS FURTHER SOUTH TOWARD I-70. MODELS SUGGEST EMPHASIS FOR HEAVY RAIN WILL BEGIN TO SHIFT SOUTHWARD TONIGHT...AS AFTERNOON/EVENING CONVECTION SINKS SOUTHEASTWARD INTO SOUTHERN ILLINOIS. WILL CARRY LIKELY POPS DURING THE EVENING...DROPPING TO CHANCE POPS AFTER MIDNIGHT. EVEN THOUGH SYNOPTIC COLD FRONT NEVER CLEARS THE AREA...MAIN FOCUS FOR CONVECTION ON TUESDAY WILL BE ALONG OLD OUTFLOW BOUNDARY FROM THE PRIOR NIGHTS STORMS...WHICH WILL LIKELY LIE SOMEWHERE IN THE OHIO RIVER VALLEY. WILL THEREFORE REMOVE RAIN CHANCES ACROSS THE NORTHERN KILX CWA TUESDAY/TUESDAY NIGHT...WITH LOW POPS CONTINUING FURTHER SOUTH. NEXT UPPER WAVE APPROACHES FROM THE WEST ON WEDNESDAY...ONCE AGAIN ACTIVATING THE STALLED FRONTAL BOUNDARY ACROSS CENTRAL ILLINOIS. WILL THEREFORE CARRY 40 POPS ACROSS THE BOARD. LONG TERM...THURSDAY THROUGH SUNDAY A STRONG UPPER LOW DIVING SOUTHEASTWARD OUT OF CANADA WILL PUSH A STRONG COLD FRONT TOWARD CENTRAL ILLINOIS WEDNESDAY NIGHT INTO THURSDAY. MODELS HAVE CONSISTENTLY SHOWN THIS FEATURE FOR THE PAST SEVERAL RUNS...SO CONFIDENCE IS GROWING THAT AN ENHANCED CHANCE FOR SHOWERS/STORMS EXISTS DURING THIS TIME FRAME. WILL MAINTAIN LIKELY POPS ALONG AND WEST OF I-55 WEDNESDAY NIGHT...THEN FURTHER EAST ACROSS EAST-CENTRAL AND SOUTHEAST ILLINOIS ON THURSDAY. FRONT WILL QUICKLY CLEAR THE AREA THURSDAY AFTERNOON...RESULTING IN COOLER AND DRIER CONDITIONS THURSDAY NIGHT THROUGH NEXT WEEKEND. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR ILZ027>031- 036>038-040>043-047>051. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LINCOLN IL 1147 AM CDT MON AUG 17 2009 ILZ027>031-036>038-040>043-047>051-181200- CASS-DE WITT-FULTON-KNOX-LOGAN-MARSHALL-MASON-MCLEAN-MENARD- MORGAN-PEORIA-SANGAMON-SCHUYLER-SCOTT-STARK-TAZEWELL-WOODFORD- 1147 AM CDT MON AUG 17 2009 ...FLASH FLOOD WATCH IN EFFECT UNTIL 7 PM CDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS...ALONG AND WEST OF I-55. .DAY ONE...THIS AFTERNOON AND TONIGHT THUNDERSTORM CHANCES WILL PERSIST INTO TONIGHT...AS A SLOW MOVING FRONTAL BOUNDARY PUSHES INTO THE REGION. HEAVY RAINFALL IS POSSIBLE WITH THE STRONGER STORMS AND THIS MAY POSE A THREAT OF FLASH FLOODING. HOWEVER...SEVERE THUNDERSTORM CHANCES ARE LOW. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE SLOW MOVING FRONTAL BOUNDARY AND A SERIES OF UPPER LEVEL DISTURBANCES WILL CONTINUE TO BRING PERIODIC CHANCES OF THUNDERSTORMS TO THE REGION FROM TUESDAY INTO THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION THROUGH TONIGHT IS NOT ANTICIPATED AT THIS TIME. ILZ044>046-052>057-061>063-066>068-071>073-181200- CHAMPAIGN-CHRISTIAN-CLARK-CLAY-COLES-CRAWFORD-CUMBERLAND-DOUGLAS- EDGAR-EFFINGHAM-JASPER-LAWRENCE-MACON-MOULTRIE-PIATT-RICHLAND- SHELBY-VERMILION- 1147 AM CDT MON AUG 17 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND SOUTHEAST ILLINOIS...EAST OF I-55. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS WILL BE POSSIBLE ACROSS THE AREA THROUGH TONIGHT...AS A SLOW MOVING FRONTAL BOUNDARY PUSHES INTO THE REGION. HEAVY RAINFALL IS POSSIBLE WITH THE STRONGER STORMS. SOME OF THE THUNDERSTORMS MAY PRODUCE GUSTY WINDS AND HAIL AS WELL...BUT NO WIDESPREAD SEVERE WEATHER IS CURRENTLY EXPECTED. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE SLOW MOVING FRONTAL BOUNDARY AND A SERIES OF UPPER LEVEL DISTURBANCES WILL CONTINUE TO BRING PERIODIC CHANCES OF THUNDERSTORMS TO THE REGION FROM TUESDAY INTO THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS CURRENTLY NOT ANTICIPATED THROUGH TONIGHT. GEELHART
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
1036 AM CDT MON AUG 17 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 AM HEAVY RAIN 2 SW ATHENS 39.94N 89.75W
08/17/2009 M1.54 INCH MENARD IL CO-OP OBSERVER
24-HOUR TOTAL
0700 AM HEAVY RAIN 2 N ATHENS 39.99N 89.72W
08/17/2009 M1.74 INCH MENARD IL CO-OP OBSERVER
24-HOUR TOTAL
0700 AM HEAVY RAIN JACKSONVILLE 39.73N 90.23W
08/17/2009 M1.90 INCH MORGAN IL CO-OP OBSERVER
24-HOUR TOTAL
0700 AM HEAVY RAIN LEWISTOWN 40.40N 90.16W
08/17/2009 M1.58 INCH FULTON IL CO-OP OBSERVER
24-HOUR TOTAL
0700 AM HEAVY RAIN MARIETTA 40.50N 90.39W
08/17/2009 M2.10 INCH FULTON IL CO-OP OBSERVER
24-HOUR TOTAL
0700 AM HEAVY RAIN 2 SW PETERSBURG 39.99N 89.88W
08/17/2009 M2.53 INCH MENARD IL CO-OP OBSERVER
24-HOUR TOTAL
0700 AM HEAVY RAIN WINCHESTER 39.63N 90.46W
08/17/2009 M3.02 INCH SCOTT IL CO-OP OBSERVER
24-HOUR TOTAL
0200 AM HEAVY RAIN BROADLANDS 39.91N 88.00W
08/17/2009 M2.81 INCH CHAMPAIGN IL MESONET
COCORAHS REPORT
0800 AM HEAVY RAIN 3 SW EMDEN 40.27N 89.53W
08/17/2009 M2.04 INCH LOGAN IL MESONET
24-HOUR TOTAL. COCORAHS REPORT
0900 AM HEAVY RAIN 5 NW ATLANTA 40.31N 89.30W
08/17/2009 M2.00 INCH LOGAN IL MESONET
COCORAHS REPORT
0600 AM HEAVY RAIN MURRAYVILLE 39.58N 90.25W
08/17/2009 M1.91 INCH MORGAN IL MESONET
COCORAHS REPORT
0630 AM HEAVY RAIN WAVERLY 39.59N 89.95W
08/17/2009 M1.55 INCH MORGAN IL MESONET
COCORAHS REPORT
&&
GEELHARTThe Lincoln radar (KILX), 88 km away, was scanning. The volume nearest the first event began at 19:44 UTC.
4 thunderstorm wind, 1 lightning. Local standard time, as filed.
A tree was blown down in Bluff Springs.
A tree was blown down in Virginia.
A power line was blown down in New Holland.
A 2-foot diameter tree was blown onto a house in Lincoln. The tree was partially dead.
A house in the city of Springfield was struck by lightning, which caused a fire in the upper level of the structure. Four people were in the house, but they all escaped without injury. The damage was confined to the attic and rooms on the second floor of the house.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2009Every state in 2009This day in weather historyWarnings in Illinois, August 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: 192274, 192275, 192276, 192277, 195149.