Waves of low pressure tracking along a nearly stationary frontal boundary draped across south-central Illinois triggered numerous thunderstorms during the afternoon and evening of July 11th. 77 being reported in Mount Pulaski in southern Logan 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.
Waves of low pressure tracking along a nearly stationary frontal boundary draped across south-central Illinois triggered numerous thunderstorms during the afternoon and evening of July 11th. Some of the storms dropped locally heavy rainfall, with as much as 3.77 being reported in Mount Pulaski in southern Logan County. Due to excessive rainfall rates and already moist soil conditions, flash flooding occurred in a few locations...particularly across portions of Sangamon, Logan, and Vermilion counties.
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 11, 2:27 PM CST, 3 hours 11 minutes earlier.
Area Forecast Discussion National Weather Service Lincoln IL 327 PM CDT Sun Jul 11 2021 .SYNOPSIS... Issued at 151 PM CDT Sun Jul 11 2021 Scattered afternoon showers and thunderstorms will again be likely Monday. Drier conditions return Tuesday through Wednesday as the current weather system finally lifts out of the region, but additional rain chances return Thursday into Friday as yet another frontal system moves across the Upper Midwest. The heat and humidity will also return by mid-week. && .SHORT TERM...(This evening) ISSUED AT 151 PM CDT Sun Jul 11 2021 Afternoon water vapor imagery reveals an upper-level low spinning over northwest Missouri. This is juxtaposed to an occluded surface low centered over west central Illinois with a cold front arcing from Springfield to Mattoon to Mount Vernon, and a surface warm front extending from Decatur to Champaign to Crawfordsville. Satellite imagery depicts an area of partial clearing across central Illinois. This has allowed conditions within the narrow warm sector to become more unstable with surface dewpoints now into the low 70s and surface-based CAPE now between 1000-1500 J/kg. There remains some decent upper- level support with a 60-70 kt 300-mb speed max veering across eastern Illinois, and a spoke of vorticity twirling over the Mississippi River Valley. Despite all of that, weak effective shear and weak effective inflow should limit severe organized convection through early this evening. On the other hand, funnel clouds/landspouts remain possible through early evening as low-level CAPE and low-level lapse rates continue to increase, and near surface vorticity becomes maximized near the preexisting boundaries. The two main areas where such nuisances could be possible are (1) far west central Illinois near the core of the surface low, and (2) east of the I-57/I-72 interchange near the warm front. Convection should quickly wane later this evening with the loss of daytime heating and no appreciable LLJ to keep things going. Overnight lows will cool into the mid 60s beneath a blanket of low stratus. && .LONG TERM...(Monday through Sunday) ISSUED AT 151 PM CDT Sun Jul 11 2021 A similar convective environment will be in place on Monday as the weather system becomes vertically stacked and gets cut-off from the main belt of westerlies. Locations west of I-55 stand the best chance for organized convection where afternoon CAPE/Shear profiles support a localized damaging wind threat. Temperatures will remain below normal through Monday as the center of low pressure slowly drifts across central Illinois. Afternoon highs will warm into the upper 70s. By Tuesday morning, the upper-level low begins to open up and lift toward the Great Lakes region as a kicker trough digs across the Canadian Prairies. Large scale subsidence will begin to work in behind the departing upper wave, and this should lead to dry conditions Tuesday through Wednesday. Afternoon temperatures will surge back into the upper 80s Wednesday into Thursday as winds veer southerly ahead of another frontal system. While we're still trying to nail down the late week system, it's looking like a multiple day episode as the main upper-level forcing becomes displaced well east of the region, leaving the cold front to slowly sag south into Illinois. The uncertainty at this point is tied to how far south the cold front will sag, with the GEFS keeping it further north (Chicago's outlook area) than the ENS (our outlook area). Regardless to where the front stalls out, it's looking like another decent QPF event for the Midwest. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1240 PM CDT Sun Jul 11 2021 Mostly MVFR to occasional IFR conditions are expected over the next 24 hours as an upper low remains positioned over the local area. Some of the southern sites (DEC and CMI) may break into VFR category this afternoon as clouds try to break for some sun. Periods of light rain or drizzle will continue through Monday morning, especially at the PIA and BMI terminals. Surface winds will back toward the northeast by 00z at all regional terminals. Sustained speeds will be 5-10 kts through the TAF period, with the higher range of those winds coming across the northern terminals (PIA and BMI). && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && SYNOPSIS...MJA SHORT TERM...MJA LONG TERM...MJA AVIATION...MJA
Hazardous Weather Outlook National Weather Service Lincoln IL 344 PM CDT Sun Jul 11 2021 ILZ027>031-037-038-042>046-048-051>057-061>063-066>068-072-073- 122045- Champaign-Christian-Clark-Coles-Crawford-Cumberland-De Witt- Douglas-Edgar-Effingham-Jasper-Knox-Lawrence-Logan-Macon-Marshall- McLean-Menard-Moultrie-Peoria-Piatt-Richland-Sangamon-Shelby- Stark-Tazewell-Vermilion-Woodford- 344 PM CDT Sun Jul 11 2021 This Hazardous Weather Outlook is for portions of central Illinois, east central Illinois, southeast Illinois and west central Illinois. .DAY ONE...TONIGHT... Scattered thunderstorms will remain possible through early evening across the area. At this time, severe weather is not expected, although a few funnel clouds could develop. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY... Thunderstorm chances will continue through Monday with additional chances toward the end of the week. The severe weather threat is unknown at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ036-040-041-047-049-050-122045- Cass-Fulton-Mason-Morgan-Schuyler-Scott- 344 PM CDT Sun Jul 11 2021 This Hazardous Weather Outlook is for portions of central Illinois and west central Illinois. .DAY ONE...TONIGHT... Scattered thunderstorms will remain possible through early evening across the area. At this time, severe weather is not expected, although a few funnel clouds could develop. Flooding will continue along the Illinois River, from Havana and downstream. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY... Thunderstorm chances will continue through Monday with additional chances toward the end of the week. The severe weather threat is unknown at this time. Flooding will continue along the Illinois River, from Havana and downstream, for the next several days. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ071-122045- Clay- 344 PM CDT Sun Jul 11 2021 This Hazardous Weather Outlook is for portions of southeast Illinois. .DAY ONE...TONIGHT... Scattered thunderstorms will remain possible through tonight across the area. At this time, severe weather is not expected. Flooding on the Little Wabash River around Clay City will continue. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY... Thunderstorm chances will continue through Monday with additional chances toward the end of the week. The severe weather threat is unknown at this time. Flooding on the Little Wabash River around Clay City will continue for the next several days. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. MJA
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
442 PM CDT SUN JUL 11 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0415 PM FUNNEL CLOUD HENNING 40.31N 87.70W
07/11/2021 VERMILION IL PUBLIC
RELAYED BY WCIA-TV.
0324 PM FUNNEL CLOUD 5 WSW ATHENS 39.93N 89.81W
07/11/2021 MENARD IL FIRE DEPT/RESCUE
&&The Lincoln radar (KILX), 15 km away, was scanning. The volume nearest the first event began at 23:38 UTC.
4 flash flood. Local standard time, as filed.
Several roads in Mt. Pulaski had about 1 foot of water flowing across them due to heavy rainfall.
Several roads in both Danville and Tilton were flooded.
Kickapoo Creek spilled out of its banks and flooded State Route 10 just west of Lincoln. A minor car accident occurred due to hydroplaning: however, no injuries were reported.
Water was flowing across the eastbound lanes of I-72 southeast of Berlin.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2021Every state in 2021This day in weather historyWarnings in Illinois, July 2021
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: 966040, 966044, 966041, 966043.