A cold front dropping southward into a very hot and humid airmass triggered widely scattered thunderstorms along and south of a Pittsfield to Danville line during the afternoon and early evening hours of August 4th. A few of the storms became severe, producing penny-sized hail and minor wind damage.
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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 cold front dropping southward into a very hot and humid airmass triggered widely scattered thunderstorms along and south of a Pittsfield to Danville line during the afternoon and early evening hours of August 4th. A few of the storms became severe, producing penny-sized hail and minor wind damage.
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 4, 1:32 PM CST, 2 hours 3 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 232 PM CDT WED AUG 4 2010 .DISCUSSION... ISSUED 147 PM CDT WED AUG 4 2010 CHALLENGES THIS AFTERNOON FOCUS ON POTENTIAL CONVECTION THIS AFTERNOON AND TONIGHT...AND TEMPERATURE TRENDS FOR NEXT WEEK. SHORT TERM...THIS AFTERNOON AND TONIGHT... SIGNIFICANT TEMPERATURE GRADIENT IN PLACE ACROSS FORECAST AREA THIS AFTERNOON WITH CLOUDY RAIN-COOLED CONDITIONS IN PLACE IN EXTREME NORTH...AND DANGEROUSLY HOT AND MUGGY CONDITIONS IN PLACE FOR CENTRAL AND SOUTHEAST PORTIONS OF THE AREA. WILL ALLOW HEADLINES TO EXPIRE AS SCHEDULED AT 7 PM. A SERIES OF CONVERGENCE BOUNDARIES ARE IN PLACE ACROSS CENTRAL ILLINOIS WITH THE STRONGEST APPARENT AS A WIND SHIFT AND CU FIELD FROM NEAR IJX TO DNV. THE 18Z KILX SPECIAL SOUNDING STILL SHOWS SIGNIFICANT CAP IN PLACE WITH A CONVECTIVE TEMPERATURE OF 101F. SO ANY ACTIVITY THAT DOES DEVELOP WILL NEED TO HAVE STRONG CONVERGENCE TO BREAK THROUGH AND MANTAIN ITSELF. WITH LIGHT WINDS...THAT LEVEL OF CONVERGENCE IS UNLIKELY. SHORT-TERM MODELS SEEM TO BE UNDERESTIMATING THE CAP AND ARE INDICATING MORE CONVECTIVE COVERAGE THAN WILL BE LIKELY. HOWEVER...ANY STORMS THAT DO DEVELOP WILL HAVE SIGNIFICANT INSTABILITY TO WORK WITH AND MAY BE CAPABLE OF STRONG WINDS. SYNOPTIC COOL FRONT OVER WISCONSIN AND IOWA IS EXPECTED TO PUSH SOUTHEAST LATER TONIGHT. THE FRONT INTERACTING WITH DEVELOPING LLJ MAY BE SUFFICIENT TO PRODUCE ELEVATED STORMS LATER TONIGHT... PARTICULAR GIVEN THE ADDED ENERGY OF A SHORTWAVE ROTATING AROUND HUDSON BAY VORTEX. WILL KEEP POPS IN PLACE IN AND NEAR THE FRONT AND SOME OF THESE STORMS MAY BE STRONG WITH THE PRIMARY THREAT BEING HEAVY RAINFALL GIVEN PRECIPITABLE WATER AMOUNTS OF AROUND 1.8 INCHES. LONG TERM...THURSDAY THROUGH WEDNESDAY... COOLER AIR FILTERS INTO CENTRAL AND SOUTHEAST ILLINOIS ON THURSDAY AND FOR THE WEEKEND. TEMPS WILL ACTUALLY BE CLOSER TO SEASONAL NORMALS. HOWEVER...MODELS REDEVELOP MID-LEVEL RIDGE OVER THE CENTRAL U.S. EARLY NEXT WEEK LEADING TO A RETURN OF ABOVE NORMAL TEMPERATURES. 12Z GFS SUGGESTS THIS WARMING MAY BE SHORT-LIVED WITH THE RIDGE RETROGRADING WESTWARD BY MIDWEEK. ECMWF IS WEAKER WITH TROUGHING OVER EASTERN CANADA AND IS SLOWER IN BREAKING THE RIDGE DOWN. THIS SOLUTION SEEMS MORE REASONABLE GIVEN THE LACK OF ZONAL FLOW. WILL KEEP TEMPS IN 90S OR NEAR 90 FOR HIGHS THROUGH WEDNESDAY. RIDGE SHOULD ALSO KEEP ILLINOIS DRY FOR THE FIRST HALF OF NEXT WEEK. CAN NOT RULE OUT ISOLATED AFTERNOON CONVECTION UNDER THE INFLUENCE OF THE FORECASTED RIDGE...BUT MOST LOCATIONS SHOULD BE DRY. BARKER && .AVIATION... ISSUED 1249 PM CDT WED AUG 4 2010 LATEST SATELLITE IMAGERY IS SHOWING A BAND OF ENHANCED CU BEGINNING TO DEVELOP FROM NEAR KIJX NORTHEASTWARD TO JUST NORTH OF KTIP. THIS MAY BE THE BEGINNING OF AFTERNOON CONVECTIVE DEVELOPMENT ALONG AN OLD OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE THEREFORE INCLUDED VCTS AT THE I-72 TERMINALS BETWEEN 19Z AND 02Z. FURTHER NORTH...HAVE NOT INCLUDED ANY MENTION OF POTENTIAL THUNDER AT KPIA...OPTING INSTEAD TO BRING IN A FEW SCATTERED SHOWERS CURRENTLY ACROSS CENTRAL/SOUTHERN IOWA. ONCE BOUNDARY DROPS A BIT FURTHER SOUTH LATER THIS EVENING...THUNDER CHANCES WILL COME TO AN AND AT ALL TAF SITES AFTER 03Z. OVERNIGHT...HIGH/THIN OVERCAST AND VERY LIGHT WINDS WILL PREVAIL. WITH PLENTY OF RESIDUAL LOW-LEVEL MOISTURE REMAINING IN PLACE EVEN AFTER PASSAGE OF FRONT...THINK PATCHY FOG WILL BE A GOOD BET TOWARD DAWN. HAVE THEREFORE INCLUDED TEMPO GROUP FOR VISBYS DOWN TO 4-5SM BETWEEN 08Z AND 12Z. AFTER THAT...MOSTLY CLEAR SKIES AND LIGHT N/NW WINDS WILL BE OBSERVED THURSDAY MORNING. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING UNTIL 7 PM CDT THIS EVENING FOR ILZ040>057-061>063-066>068-071>073. HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ027>031-036>038. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LINCOLN IL 315 PM CDT WED AUG 4 2010 ILZ027>031-036>038-051100- FULTON-KNOX-MARSHALL-MCLEAN-PEORIA-STARK-TAZEWELL-WOODFORD- 315 PM CDT WED AUG 4 2010 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS. .DAY ONE...TONIGHT HOT AND HUMID CONDITIONS WILL CONTINUE INTO THIS EVENING...WITH HEAT INDICES HOVERING AROUND 100 DEGREES. SCATTERED THUNDERSTORMS WILL DEVELOP ALONG AN OUTFLOW BOUNDARY STRETCHING FROM NORTHERN MISSOURI INTO CENTRAL ILLINOIS THIS EVENING. BASED ON THE LATEST SATELLITE IMAGERY...IT APPEARS THE BEST CHANCE FOR STORM DEVELOPMENT WILL BE SOUTH OF A CANTON TO BLOOMINGTON-NORMAL LINE. ANY STORMS THAT FIRE WILL BE CAPABLE OF FREQUENT LIGHTNING AND TORRENTIAL RAINFALL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. ILZ040>057-061>063-051100- CASS-CHAMPAIGN-CHRISTIAN-CLARK-COLES-CUMBERLAND-DE WITT-DOUGLAS- EDGAR-LOGAN-MACON-MASON-MENARD-MORGAN-MOULTRIE-PIATT-SANGAMON- SCHUYLER-SCOTT-SHELBY-VERMILION- 315 PM CDT WED AUG 4 2010 ...EXCESSIVE HEAT WARNING IN EFFECT UNTIL 7 PM CDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS AND EAST CENTRAL ILLINOIS. .DAY ONE...TONIGHT DANGEROUS LEVELS OF HEAT WILL CONTINUE INTO THIS EVENING...WITH HEAT INDICES HOVERING IN THE 105 TO 110 DEGREE RANGE. SCATTERED THUNDERSTORMS WILL DEVELOP ALONG AN OUTFLOW BOUNDARY STRETCHING FROM NORTHERN MISSOURI INTO CENTRAL ILLINOIS THIS EVENING. BASED ON THE LATEST SATELLITE IMAGERY...IT APPEARS THE BEST CHANCE FOR STORM DEVELOPMENT WILL BE ALONG AND SOUTH OF A CANTON TO BLOOMINGTON-NORMAL LINE. ANY STORMS THAT FIRE WILL BE CAPABLE OF FREQUENT LIGHTNING AND TORRENTIAL RAINFALL. SOME OF THE STRONGEST CELLS COULD POTENTIALLY PRODUCE DAMAGING WIND GUSTS AS WELL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING THROUGH 10 PM. ILZ066>068-071>073-051100- CLAY-CRAWFORD-EFFINGHAM-JASPER-LAWRENCE-RICHLAND- 315 PM CDT WED AUG 4 2010 ...EXCESSIVE HEAT WARNING IN EFFECT UNTIL 7 PM CDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST ILLINOIS. .DAY ONE...TONIGHT DANGEROUS LEVELS OF HEAT WILL CONTINUE INTO THIS EVENING...WITH HEAT INDICES EXCEEDING 110 DEGREES. THERE WILL BE A CHANCE FOR THUNDERSTORMS TONIGHT AS A FRONTAL BOUNDARY SINKS SLOWLY SOUTHWARD INTO THE REGION. FREQUENT LIGHTNING AND LOCALLY HEAVY RAINFALL WILL BE LIKELY WITH THE STORMS. SOME OF THE STRONGEST CELLS COULD POTENTIALLY PRODUCE DAMAGING WIND GUSTS AS WELL...ESPECIALLY DURING THE EVENING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORM CHANCES WILL LINGER INTO THURSDAY AS THE FRONT REMAINS IN THE VICINITY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING BETWEEN 6 PM AND MIDNIGHT. BARNES
The Lincoln radar (KILX), 78 km away, was scanning. The volume nearest the first event began at 21:35 UTC.
3 thunderstorm wind, 1 hail. Local standard time, as filed.
Several trees were blown down in Virginia.
A metal carport was blown across a street, causing damage to the roof and side of Parlier's Auto Body.
Numerous trees and power lines were blown down on the north side of Danville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2010Every state in 2010This day in weather historyWarnings in Illinois, August 2010
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: 257767, 257770, 257765, 257768.