A deep upper-level trough over the Midwest helped triggered scattered thunderstorms across central Illinois during the afternoon of August 21st. A few of the storms produced gusty winds of between 50 and 60 mph, with one cell producing wind damage in the town of Lerna in Coles County.
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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.
A deep upper-level trough over the Midwest helped triggered scattered thunderstorms across central Illinois during the afternoon of August 21st. A few of the storms produced gusty winds of between 50 and 60 mph, with one cell producing wind damage in the town of Lerna in Coles County.
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 21, 5:15 PM CST, 1 hour 17 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 615 PM CDT FRI AUG 21 2009 .DISCUSSION... ISSUED 216 PM CDT FRI AUG 21 2009 THE UNSEASONABLY COOL AIRMASS THAT HAS ARRIVED TODAY WILL LINGER THROUGH MONDAY...AS HIGH PRESSURE BUILDS INTO IL THIS WEEKEND. THE LONG WAVE UPPER TROUGH WILL SLIDE JUST EAST OF IL ON SATURDAY...WITH DEEP LAYER NORTHWEST FLOW PROVIDING A SUSTAINED SOURCE OF COLDER AIR. CONDITIONS WILL SWING BACK TO NORMAL AUG TEMPS FOR TUESDAY AND WEDNESDAY AS SOUTHERLY FLOW INCREASES AHEAD OF THE NEXT COLD FRONT. MODEL GUID IS RATHER CLOSE THROUGH NEXT TUES...THEN DIFFERENCES EMERGE CONCERNING THE PASSAGE OF THE NEXT COLD FRONT. GENERALLY FOLLOWED THE GFS TIMING...AS THE ECMWF AND CANADIAN ALL PROVIDED DIFFERING SOLUTIONS. PERSISTENCE GENERALLY MATCHED WELL WITH THE GFS FOR NEXT WEEKS FRONT. SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT. A STRONG UPPER SHORTWAVE IS EVIDENT ON THE SATELLITE LOOPS ACROSS IOWA AND S MN. THE WAVE WILL BE PROPELLED SE ACROSS IL THIS AFTERNOON AND EVENING BY A 95KT JET MAX DIVING DOWN THE BACK SIDE OF THE UPPER TROUGH. SHOWERS WILL LIKELY LINGER THIS EVENING AS A RESULT...SINCE THEY WILL NOT BE JUST DIURNALLY DRIVEN. SUNSET MAY HELP REDUCE THE INTENSITY AND COVERAGE OF THE SHOWERS...BUT WE EXPECT SOME SHOWER ACTIVITY TO LINGER THROUGH LATE EVENING. LOWS TONIGHT WILL BE ABOUT 5 DEG COOLER THAN FRIDAY MORNING. CLOUD COVER WILL WORK TO KEEP TEMPS WARMER TONIGHT...ALTHOUGH THE AMBIENT AIRMASS WILL BE ENOUGH TO PUT LOWS IN THE MID 50S. SATURDAY MORNING WILL SEE THE AXIS OF THE COLD POOL ALOFT SETTLE INTO EASTERN IL. CLOUDS WILL LIKELY LINGER UNTIL LATER SATURDAY. ANY SUNSHINE ON SATURDAY WILL MOST LIKELY LEAD TO A LAYER OF STRATO-CUMULUS CLOUDS. WILL KEEP SHOWERS OUT OF THE FORECAST...BUT WOULD NOT BE SURPRISED TO SEE A FEW SPRINKLES DEVELOP EAST OF I-55...CLOSER TO THE COLDEST AIR. THE COMBINATION OF CLOUDS AND CHILLY AIR WILL CAUSE HIGHS TO STRUGGLE TO REACH THE MID 70S. HIGHS SHOULD SETTLE OUT ALMOST 10 DEGREES BELOW NORMAL. SAT NIGHT...SKIES WILL CLEAR OUT AND WINDS WILL BECOME CALM. THAT WILL SET THE STAGE FOR THE COLDEST NIGHT OF THE NEXT WEEK...WITH LOWS IN THE LOW 50S...ABOUT 10 DEG BELOW NORMAL. SUNDAY WILL FEATURE A SLIGHT WARMING TREND...PRIMARILY DUE TO NEARLY FULL SUN. THE SUN ANGLE IS STILL RATHER HIGH...SO IT WILL NOT TAKE MUCH TO OVERCOME THE COLDER AIR. HIGHS SHOULD CLIMB INTO THE UPPER 70S/ARND 80...STILL SLIGHTLY BELOW NORMAL. ANOTHER CLEAR AND COOL NIGHT IS EXPECTED SUNDAY NIGHT...UNDER HIGH PRESSURE. LONG TERM...MONDAY THROUGH FRIDAY. SOUTHEASTERLY FLOW WILL DEVELOP AT THE SURFACE ON MONDAY...AS THE RIDGE AXIS MOVES JUST EAST OF IL. H85 TEMPS WILL BEGIN A WARMING TREND...WITH ENOUGH DRY AIR ALOFT TO ALLOW FOR MOSTLY SUNNY SKIES. HIGHS SHOULD REACH NEAR NORMAL...IN THE LOW TO MID 80S. TUESDAY WILL BE THE WARMEST DAY OF THE NEXT WEEK...AS H85 TEMPS CLIMB BACK INTO THE LOW 20C RANGE. EXTRAPOLATING THE MIXING LAYER DOWN FROM 4-5K FT INDICATES HIGH TEMPS SHOULD REACH INTO THE UPPER 80S IN MOST AREAS. BASED ON GFS TIMING...THE COLD FRONT WILL REACH SE IOWA BY 12Z WED...WITH MOST OF THE PRECIP BEING POST FRONTAL. WILL KEEP SOME SLIGHT CHANCE POPS IN THE NW CWA ON TUES NIGHT AND WED...AS SOME ISOLATED SHOWERS MAY BUBBLE UP IN THE WAA AIRFLOW AHEAD OF THE FRONT. WILL KEEP CHANCE POPS IN THE NW THIRD OF THE CWA FOR WED NIGHT...AND PROGRESS THE CHANCE POPS INTO THE SE 2/3RDS OF THE CWA FOR THURSDAY. THE COLD FRONT SHOULD PUSH SE OF OUR AREA ON THURSDAY NIGHT...HELPING TO DIMINISH PRECIP ACTIVITY. WILL KEEP SLIGHT CHANCE POPS EVERYWHERE ON THUR NIGHT AND FRIDAY...AS THE 12Z ECMWF IS CONTINUING TO INDICATE A WAVE MOVING ACROSS IL DURING THAT TIME. WILL NOT RULE OUT THAT POSSIBILITY. SHIMON && .AVIATION... ISSUED 615 PM CDT FRI AUG 21 2009 VIGOROUS UPR SHORTWAVE AND ASSOC SFC TROF MOVG EWD ACRS CNTL IL ATTM. SCT PCPN WL BE DCRSG WITH TIME AS SYSTEM MOVS E AND THE SUN GOES DOWN. QUITE A BIT OF THE STRATOCU OVR THE AREA IS DIRUNAL... HWVR LOW LVL MSTR AND CONTD CYCLONIC LOW LVL FLOW WL BE SUFFICIENT FOR SCT-BKN 3K-5K FT CLDS INTO THE OVRNGT. SFC HI WL BE PUSHING INTO IL FOR SAT WITH NLY SFC WNDS AROUND 10 KT. EXPECT ONE MORE DAY OF BKN STRATOCU AFT 16Z SAT...AND AN ISOLD SHWR NOT OUT OF THE QUESTION IN ERN AREAS AROUND CMI. THIS ACTVTY SHOULD BE ISOLD AND DOES NOT MERIT MENTION IN THE TAF ATTM. 04 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LINCOLN IL 350 PM CDT FRI AUG 21 2009 ILZ027>031-036>038-040>057-061>063-066>068-071>073-221100- CASS-CHAMPAIGN-CHRISTIAN-CLARK-CLAY-COLES-CRAWFORD-CUMBERLAND- DE WITT-DOUGLAS-EDGAR-EFFINGHAM-FULTON-JASPER-KNOX-LAWRENCE-LOGAN- MACON-MARSHALL-MASON-MCLEAN-MENARD-MORGAN-MOULTRIE-PEORIA-PIATT- RICHLAND-SANGAMON-SCHUYLER-SCOTT-SHELBY-STARK-TAZEWELL-VERMILION- WOODFORD- 350 PM CDT FRI AUG 21 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS...EAST CENTRAL ILLINOIS AND SOUTHEAST ILLINOIS. .DAY ONE...TONIGHT SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE INTO THIS EVENING. DUE TO THE COLD AIR ALOFT...SOME OF THESE MAY PRODUCE SMALL HAIL AND FUNNEL CLOUDS...BUT SEVERE WEATHER IS NOT EXPECTED. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. HJS
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
448 PM CDT FRI AUG 21 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0410 PM TSTM WND GST 3 SW PEORIA 40.71N 89.65W
08/21/2009 M59 MPH PEORIA IL ASOS
&&
25PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
455 PM CDT FRI AUG 21 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0450 PM TSTM WND GST GOODFIELD 40.63N 89.27W
08/21/2009 E55 MPH WOODFORD IL EMERGENCY MNGR
ALSO PEA SIZED HAIL
&&
25The Lincoln radar (KILX), 121 km away, was scanning. The volume nearest the first event began at 00:32 UTC.
1 thunderstorm wind. Local standard time, as filed.
Several trees were blown down in Lerna. One tree fell on a car, while two others fell on houses, causing roof damage.
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: 192279.