Isolated showers developed across north central Illinois during the evening of July 4th. A landspout tornado was observed near one of these showers.
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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.
Isolated showers developed across north central Illinois during the evening of July 4th. A landspout tornado was observed near one of these showers.
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 Jul 4, 5:20 PM CST, 42 minutes earlier.
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 620 PM CDT Sat Jul 4 2020 .SHORT TERM... 208 PM CDT Through Sunday night... Weak surface high pressure will remain in place across the western Great Lakes region through the remainder of the Independence Day weekend. Hot and slightly more humid weather will persist, with lake breezes cooling areas near Lake Michigan. An isolated afternoon shower or thunderstorm can't be completely ruled out, though the likelihood remains quite low. Early afternoon GOES water vapor imagery depicts a weak mid-level short wave propagating southeast across southern Lake Michigan and adjacent portions of lower Michigan and northern Indiana. RAP initialized soundings indicate fairly dry thermodynamic profiles above the boundary layer, which along with relatively warm mid-level temps and poor mid-level lapse rates should limit development of any extensive cloud cover. Regional surface obs do show that boundary layer dew points have crept up a bit, especially within the marine layer off of Lake Michigan where dew points in the upper 60s/around 70 were noted, as well as hazy conditions over the cooler lake waters. Thus while temps across the region are fairly similar to this time yesterday, the heat index has nudged up a bit, with some low-mid 90s observed early this afternoon. Warm/dry sounding profiles are generally not favorable for convective development, an isolated afternoon shower or thunderstorm can't be completely ruled out in the vicinity of the lake breeze boundary, where slightly higher marine-influenced dew points and localized convergence could perhaps produce deeper convective updrafts during peak heating. Better chances will exist farther east/southeast into Indiana however, where slightly cooler mid-level temps will be found beneath the aforementioned mid-level short wave. More of the same appears to be in store for the region Sunday, though with a slight increase in low level warmth. Temps in the 925- 850 mb layer are progged to warm a Celsius degree or so on Sunday, supporting temps solidly into the lower 90s away from the Lake Michigan shore, and probably a mid-90 reading in a spot or two. With surface dew point temps again in the mid-upper 60s during peak heating, the heat index will likely top out in the mid 90s for the most part, with a few upper 90s possible. Similarly to today, an isolated shower or thunderstorm is not completely out of the question, with the afternoon lake breeze boundary again the primary focus for initiation, though as today the potential for any isolated storms looks to be greater off to the east of the cwa across southwest Michigan and north central Indiana. Nighttime conditions both tonight and Sunday night will be mostly clear/partly cloudy, with mild overnight temps from the mid-60s to lower 70s. Ratzer && .LONG TERM... 249 PM CDT Monday through Saturday... Hot and increasingly humid weather continues to be the key message for the long term period as the area remains locked within a persistent summertime pattern. This continues to be the primary forecast concern, especially considering we could be approaching heat advisory criteria (Heat indices around 105 degrees) in some areas Wednesday and Thursday. Monday still is appearing to be a precipitation free day across most of the area, as we continue to only carry some slight chances for afternoon isolated storms. Humidity will increase a bit Monday, but heat indices should remain at or below 100, with actual temps in the low 90s inland from the lake. Cooler afternoon temperatures (in the lower 80s) are likely near the lake due to the likelihood of an lake breeze. The heat and humidity will ramp up by mid week as heights aloft build across the Mississippi Valley and lower Great Lakes concurrently with the northward flux of the humid airmass currently residing to our south. The net result of this will be hot and humid conditions Tuesday through at least Thursday, with Wednesday and Thursday potentially being the most oppressive. Temperatures on these days are forecast to be into the mid 90s, with dew points into the lower 70s, which would support heat indices in the 100 to 105 range. Unlike the last few days, we will have some occasional diurnal thunderstorm chances with the arrival of this very humid airmass. Capping should become minimal, so we cannot rule out the possibility for some isolated to widely scattered afternoon storms at times Tuesday through Thursday. While this is the case, the best potential for a higher coverage of thunderstorms is looking to be late Thursday into Friday as a more substantial mid-level disturbance and surface cold front approaches. KJB && .AVIATION... For the 00Z TAFs... Some minor VSBY restrictions in smoke from fireworks could occur later this evening, particularly at MDW, though with far fewer firework shows than normal, confidence is low. Cannot rule out some brief MVFR VSBY at RFD with BR/HZ pre-dawn Sunday. Otherwise, look for VFR conditions and light winds through the TAF cycle. - Izzi && .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 310 PM CDT Sat Jul 4 2020 ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002- 010-011-019-052015- 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- 310 PM CDT Sat Jul 4 2020 /410 PM EDT Sat Jul 4 2020/ This Hazardous Weather Outlook is for portions of North Central Illinois...Northeast Illinois and Northwest Indiana. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Sunday... Limited Excessive Heat Risk. Monday and Tuesday... Limited Thunderstorm Risk. Limited Excessive Heat Risk. Wednesday through Friday... Limited Thunderstorm Risk. Elevated Excessive Heat Risk. DISCUSSION: The continued heat primarily away from the Lake Michigan shore will be accompanied by much more uncomfortable humidity levels during the work week. Thus the heat impacts could increase in magnitude by the middle to late week period. Isolated to widely scattered thunderstorms will also be possible at times. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be necessary through tonight. LMZ740>745-052015- 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- 310 PM CDT Sat Jul 4 2020 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. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Tuesday through Friday... 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
The Quad Cities radar (KDVN), 81 km away, was scanning. The volume nearest the first event began at 00:04 UTC.
1 tornado. Local standard time, as filed.
Video and photos were shared of a brief landspout tornado that occurred in an open field. No damage was reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2020Every state in 2020This day in weather historyThe tornado archive for Illinois, 2020Warnings in Illinois, July 2020
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: 908262.