Scattered thunderstorms moved across portions of east central Illinois during the afternoon of October 3rd. One of the storms produced a brief tornado in a corn field in Iroquois 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 LOT wrote it up.
Scattered thunderstorms moved across portions of east central Illinois during the afternoon of October 3rd. One of the storms produced a brief tornado in a corn field in Iroquois County. No damage was reported.
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 Chicago, IL wrote its last area forecast discussion before the first event at Oct 3, 1:55 PM CST, 31 minutes earlier.
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 255 PM CDT Sun Oct 3 2021 .SHORT TERM... 255 PM CDT Through Monday night... The main mid-level impulse is currently overhead across much of northern IL. This feature will continue to support diurnal scattered showers and thunderstorms for a few more hours this afternoon, before the activity begins to diminish into early this evening. There will continue to be a small chance for a few widely scattered showers at times tonight as upper level energy and moisture try to wrap southward around the back side of the departing mid-level low, but the best chance for more scattered showers looks to hold off for most until Monday morning. Winds will turn northerly tonight and on Monday as the area of low pressure shifts to our east. As this occurs, it is likely that the fog and low CIGs to our north over northern sections of Lake Michigan will shift southward down the lake into our area. For this reason, I have added some fog to the public forecast for tonight into Monday morning. While it appears likely the area will have another period of low CIGs (under 1,000 ft AGL), it remains a bit unclear as to the extent of the fog threat late tonight, especially over inland areas of northern IL. It is possible that the main fog threat remains closer to Lake Michigan into Monday morning as the dense fog over the northern section of the lake shifts southward tonight. Any fog that develops will improve later in the morning. The scattered shower threat on Monday will be tied to a smaller scale mid-level disturbance that looks to rotate around the back side of the main mid-level low. More thunderstorms will also be possible into the afternoon, but the best chance for any storms look to be mainly south of I-80. Locally heavy downpours will likely accompany these showers. Otherwise, expect the showers/storms to diminish through the late afternoon and early evening hours. KJB && .LONG TERM... Monday Night through Sunday... 235 PM...Main forecast concern and focus is precip chances mid/late week. By Monday night, the current upper low will be weakening only to be absorbed and then replaced by another upper low that will slowly lift north from the gulf coast, reaching the local area by Thursday. There is a chance for a few showers Monday evening and again Tuesday afternoon/evening, mainly across the southern cwa but much of this time period is expected to be dry. Precip chances will increase on Wednesday as the upper low begins its move north. The models are in decent agreement with timing and blended likely pops seem on track, especially for the afternoon/evening of Wednesday and Thursday. Similar to this current upper low, locally heavy rain with the stronger thunderstorms will be possible. Precip chances begin to diminish Friday as the upper low weakens and lifts to the northeast. Precip chances for next weekend look rather low, though there is a frontal boundary on the models for the Sunday time period. Low chance pops during this time period seem ok from this distance. cms && .AVIATION... For the 18Z TAFs... 1248 PM...Primary forecast concerns include... Scattered thunderstorms this afternoon. Wind shift to northeast late this afternoon/early evening. Lifr cigs and possible fog Monday morning. Scattered thunderstorms are developing around the Chicago terminals early this afternoon and included tempo thunder mention along with the longer vicinity mention. Only medium confidence for timing and its possible updates will be needed. The strongest storms will produce brief heavy rain, possibly lowering vis into the 1-2sm range as well as locally gusty winds. Expect a slow decrease in coverage and intensity by late afternoon with some showers possible into the the evening. There may still be some lingering showers overnight into Monday morning. Westerly winds are expected through mid afternoon and it appears there will be a shift to the northeast for ord/mdw/gyy though speeds are expected to remain under 10kts. Fairly low confidence for when winds will turn northeast and updates to winds may be needed as trends emerge. Winds may drift back to north/northwest later this evening and then turn north/northeast in the predawn hours Monday, remaining northeasterly for the rest of the period. Mvfr cigs will be possible this afternoon, mainly with any showers and thunderstorms. Cigs will trend back to low mvfr later this evening and into lifr overnight with guidance in good agreement on these cigs for Monday morning, lifting to low mvfr by mid/late Monday morning. Some fog is also possible Monday morning but confidence is low given the low cigs that are expected and for now have only included mvfr vis at gyy. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && Visit us at weather.gov/chicago Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSChicago www.twitter.com/NWSChicago www.youtube.com/NWSChicago
Hazardous Weather Outlook National Weather Service Chicago/Romeoville IL 315 PM CDT Sun Oct 3 2021 ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002- 010-011-019-042015- Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage- La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford- Northern Cook-Central Cook-Southern Cook-Northern Will- Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton- 315 PM CDT Sun Oct 3 2021 /415 PM EDT Sun Oct 3 2021/ This Hazardous Weather Outlook is for portions of North Central Illinois...Northeast Illinois and Northwest Indiana. .DAY ONE...Tonight. Weather hazards expected... Limited Thunderstorm Risk. Elevated Fog Risk. DISCUSSION... Scattered thunderstorms will continue into early this evening. Locally heavy rainfall will be possible with these thunderstorms, but severe weather is not expected. Fog will be possible tonight, especially near the lake, where some dense fog may develop late. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Monday... Limited Thunderstorm Risk South of I-80. Elevated AM Fog Risk. Wednesday and Thursday... Limited Thunderstorm Risk. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be necessary through tonight. GENERAL STORM MOTION OF THE DAY: Moving towards the east at 15 to 20 mph LMZ740>745-042015- Winthrop Harbor to Wilmette Harbor IL- Wilmette Harbor to Northerly Island IL- Northerly Island to Calumet Harbor IL- Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN- Burns Harbor to Michigan City IN- 315 PM CDT Sun Oct 3 2021 This Hazardous Weather Outlook is for portions of the Illinois nearshore waters of Lake Michigan and the Indiana nearshore waters of Lake Michigan. .DAY ONE...Tonight. Weather hazards expected... Limited Thunderstorm Risk. Elevated Fog Risk. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Monday... Hazardous conditions for small craft are likely. Elevated Fog Risk. Wednesday and Thursday... Limited Thunderstorm Risk. KJB Visit us at http://weather.gov/chicago Follow us on Facebook, Twitter, and Youtube at: www.facebook.com/nwschicago www.twitter.com/nwschicago www.youtube.com/nwschicago
SPECIAL WEATHER STATEMENT National Weather Service Chicago/Romeoville IL 107 PM CDT Sun Oct 3 2021 ILZ033-039-INZ010-011-019-032100- Iroquois-Ford-Newton-Jasper-Benton- Including the cities of Watseka, Gilman, Paxton, Gibson City, Roselawn, Kentland, Morocco, Rensselaer, DeMotte, Fowler, and Oxford 107 PM CDT Sun Oct 3 2021 /207 PM EDT Sun Oct 3 2021/ ...Funnel Clouds Possible This Afternoon... At 1230 PM, trained weather spotters reported a funnel cloud north of Champaign near Thomasboro. Atmospheric conditions exist today across east central Illinois and parts of northwestern Indiana that favor the possible formation of weak circulations. Some of these circulations are occurring underneath developing showers and thunderstorms, where a funnel cloud may develop. Once the rain begins, the funnel cloud dissipates. Low hanging clouds can also appear to dip up and down at times, but they will not show signs of any rapid rotation. An actual funnel cloud will exhibit spinning in a counter-clockwise direction. In rare instances, these funnels may briefly touch down. Stay alert and be prepared to move to a safe shelter if a funnel cloud approaches the ground.
The Chicago radar (KLOT), 76 km away, was scanning. The volume nearest the first event began at 20:26 UTC.
1 tornado. Local standard time, as filed.
Trained spotters reported a brief tornado touched down in a corn field northwest of Ashkum. No known damage was caused by the tornado.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2021Every state in 2021This day in weather historyThe tornado archive for Illinois, 2021Warnings in Illinois, October 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: 986944.