Outflow boundaries from previous convection served as the focusing mechanisms for scattered thunderstorm development across central Illinois during the afternoon and evening of June 29th. One cluster of storms dropped heavy rainfall northeast of Springfield in Sangamon County, causing localized flash flooding and a few road closures.
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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.
Outflow boundaries from previous convection served as the focusing mechanisms for scattered thunderstorm development across central Illinois during the afternoon and evening of June 29th. One cluster of storms dropped heavy rainfall northeast of Springfield in Sangamon County, causing localized flash flooding and a few road closures.
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 Jun 29, 6:57 PM CST, 57 minutes earlier.
Area Forecast Discussion National Weather Service Lincoln IL 757 PM CDT Tue Jun 29 2021 .SYNOPSIS... Issued at 757 PM CDT Tue Jun 29 2021 We have a couple more days of periodic showers and thunderstorms on tap, with locally heavy rain remaining a concern. Areas south of a Jacksonville to Danville line stand the best chance of seeing a widespread heavy rain. This wet and humid weather pattern will finally break down late in the week, and the upcoming holiday weekend looks cooler, less humid, and dry. && .UPDATE... Issued at 757 PM CDT Tue Jun 29 2021 A number of outflow boundaries are evident on radar early this evening, and several storms have formed along them. A recent storm that went across Springfield produced 1 to 2 inches in less than an hour over parts of the area. Most of the evening thunderstorm activity has been near and south of I-72, with light showers to the north. While activity wanes, there doesn't really appear to be a solid period of dry conditions coming up overnight, so 30-40% PoP's will be maintained overnight. The flash flood watch was allowed to expire at 7 pm, with the flood threat diminishing as we get past sunset. Some consideration may be needed for another watch for Wednesday and Thursday, but any decisions will hold off until after the upcoming evening model runs can be analyzed. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 354 PM CDT Tue Jun 29 2021 Widely scattered thunderstorms are in place across central IL this afternoon, with a messy pattern of weak forcing responsible for the scattered nature of thunderstorms. An outflow boundary washing out in east central IL was responsible for some of the first storms, but additional weak boundaries have developed some thunderstorms as well. Strongest shear is toward northern IL where effective bulk shear around 30 kts is noted, while there is a corridor of around 3000 J/kg MLCAPE broadly around I-55 to I-57. Overlap of forcing, instability, and shear generally aligns with SPC's marginal risk area in northeast IL, mainly for downburst wind potential. With loss of diurnal heating overnight, activity should diminish this evening into overnight. Another disturbance is likely toward morning moving out of northern Missouri and should bring an increase in shower and thunderstorm activity. .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 354 PM CDT Tue Jun 29 2021 Late Wednesday into Wednesday night the frontal zone stalled to the north/northwest should push southward into and across central IL. Meanwhile, strongest instability looks to slip southeastward into southern IL. As the front slowly moves southward, shower activity should continue into Thursday, then gradually diminish from the north later Thursday. Behind the front cooler and much drier air arrives in central IL Thursday night through the weekend, with dewpoints in the 50s expected, and highs dropping to upper 70s Friday and Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 630 PM CDT Tue Jun 29 2021 Thunderstorms have been widely scattered and it has been difficult to pin down anything other than a VCTS mention, but with recent development near KSPI, will include a TEMPO period there for brief MVFR/IFR visibility in heavy rain. Elsewhere, much of the thunder has been waning as we get into early evening. Additional thunderstorm development is expected by midday across central Illinois. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && UPDATE...Geelhart SYNOPSIS...Geelhart SHORT TERM...37 LONG TERM...37 AVIATION...Geelhart
Hazardous Weather Outlook National Weather Service Lincoln IL 327 PM CDT Tue Jun 29 2021 ILZ043>046-053-055-057-302030- Champaign-De Witt-Douglas-Edgar-Macon-Piatt-Vermilion- 327 PM CDT Tue Jun 29 2021 This Hazardous Weather Outlook is for portions of central Illinois and east central Illinois. .DAY ONE...TONIGHT... Strong to isolated severe thunderstorms are possible through tonight. A few of these storms may produce locally damaging winds and heavy rain. Minor flooding will continue along portions of the Sangamon River near Monticello. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY... Thunderstorms are possible Wednesday through Thursday. The potential for widespread severe weather is low. However, locally heavy rain will be possible. Minor flooding will continue along portions of the Sangamon River near Monticello through the week. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed into this evening. Rainfall reports are appreciated. ILZ030-031-038-302030- Marshall-McLean-Woodford- 327 PM CDT Tue Jun 29 2021 ...FLASH FLOOD WATCH IN EFFECT UNTIL 7 PM CDT THIS EVENING... This Hazardous Weather Outlook is for portions of central Illinois. .DAY ONE...TONIGHT... Strong to isolated severe thunderstorms are possible through tonight. A few of these storms may produce locally damaging winds and heavy rain. Due to recent heavy rains and flooding, renewed flooding may result, especially east of the Illinois River Valley. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY... Thunderstorms are possible Wednesday through Thursday. The potential for widespread severe weather is low. However, locally heavy rain will be possible. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed into this evening. Rainfall and flooding reports are appreciated. ILZ027>029-036-037-040>042-047>051-302030- Cass-Fulton-Knox-Logan-Mason-Menard-Morgan-Peoria-Sangamon- Schuyler-Scott-Stark-Tazewell- 327 PM CDT Tue Jun 29 2021 ...FLASH FLOOD WATCH IN EFFECT UNTIL 7 PM CDT THIS EVENING... This Hazardous Weather Outlook is for portions of central Illinois and west central Illinois. .DAY ONE...TONIGHT... Periods of showers and thunderstorms are expected through tonight. These storms are not expected to be severe, but heavy rain and localized flooding will be possible. Moderate flooding will develop along the Sangamon in Chandlerville tonight and at Oakford on Wednesday. The Salt Creek near Greenview will fall from moderate to minor flooding tonight. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY... Thunderstorms are possible Wednesday through Thursday. The potential for widespread severe weather is low. However, locally heavy rain will be possible. Flooding will continue along portions of the Sangamon River from Oakford downstream and Salt Creek. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. However, rainfall and flooding reports would be greatly appreciated. ILZ052-054-056-061>063-066>068-071>073-302030- Christian-Clark-Clay-Coles-Crawford-Cumberland-Effingham-Jasper- Lawrence-Moultrie-Richland-Shelby- 327 PM CDT Tue Jun 29 2021 This Hazardous Weather Outlook is for portions of central Illinois, east central Illinois and southeast Illinois. .DAY ONE...TONIGHT... Scattered thunderstorms are possible through tonight. A few of these storms may produce gusty winds and heavy rain. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY... Thunderstorms are possible Wednesday through Thursday. A few strong to severe storms are possible Wednesday afternoon and evening. Damaging winds and heavy rainfall are the main threats. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected through tonight. NMB
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
434 PM CDT TUE JUN 29 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0300 PM TSTM WND GST 1 W HOOPESTON 40.47N 87.69W
06/29/2021 M52 MPH VERMILION IL CO-OP OBSERVER
&&Special Weather Statement National Weather Service Lincoln IL 531 PM CDT Tue Jun 29 2021 ILZ038-292315- McLean- 531 PM CDT Tue Jun 29 2021 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN MCLEAN COUNTY UNTIL 615 PM CDT... At 531 PM CDT, Doppler radar was tracking a strong thunderstorm near Downs, or 5 miles southeast of Bloomington, moving east at 40 mph. Wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Bloomington, Colfax, Downs, Saybrook, Cooksville, Arrowsmith, Ellsworth, Anchor, Bloomington Airport, Holder and Moraine View State Park. This includes Interstate 74 between mile markers 135 and 147. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4039 8846 4034 8897 4047 8903 4061 8846 TIME...MOT...LOC 2231Z 254DEG 37KT 4043 8892 Geelhart
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
731 PM CDT TUE JUN 29 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0730 PM HEAVY RAIN RIVERTON 39.85N 89.54W
06/29/2021 M1.59 INCH SANGAMON IL PUBLIC
MOST OF WHICH FELL IN UNDER 1 HOUR.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
824 PM CDT TUE JUN 29 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0822 PM TSTM WND GST PANA 39.39N 89.08W
06/29/2021 E50 MPH CHRISTIAN IL PUBLIC
1-2 INCH TREE LIMB DOWN IN PANA. RELAYED VIA
SOCIAL MEDIA. TIME ESTIMATED BY RADAR.
&&The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Third Street near Center Park was flooded in Riverton, eastbound Route 36 was impassible in several spots just southwest of Riverton, and Camp Butler Road was closed due to high water just east of Roselawn Cemetery near Clear Lake.
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, June 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: 962366.