On the evening of May 7th, a line of thunderstorms produced severe winds, severe hail, heavy rain, and even two landspouts across parts of the southern and southwestern Chicago metro. The heaviest of the rainfall occurred along a narrow corridor stretching from far southern Lee County southeastward into east-central Kankakee County where widespread 2+ inch rainfall totals were reported with a…
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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.
On the evening of May 7th, a line of thunderstorms produced severe winds, severe hail, heavy rain, and even two landspouts across parts of the southern and southwestern Chicago metro. The heaviest of the rainfall occurred along a narrow corridor stretching from far southern Lee County southeastward into east-central Kankakee County where widespread 2+ inch rainfall totals were reported with a few spots seeing between four and five inches of rain. Additionally, strong outflow winds from nearby thunderstorms kicked up significant amounts of blowing dust across parts of southern LaSalle County and towards the I-55 corridor in Livingston County. This was preceded by an abnormally dry period stretching back to early April leading to dry soil conditions in the area. Multiple reports of near-zero visibility resulted in the issuance of two Dust Storm Warnings, the first such warnings issued by the Chicago WFO.
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 May 7, 5:17 PM CST, 13 minutes earlier.
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 617 PM CDT Sun May 7 2023 .MESOSCALE DISCUSSION... Issued at 617 PM CDT Sun May 7 2023 Tricky forecast this evening. Lake breeze is catching up with the synoptic front from east to west, with synoptic boundary slowing or stalling the southward progress of the lake breeze front. Farther south, there is a convectively induced baroclinic zone that really is throwing in wrench in things and leading to a high degree of uncertainty in the evolution of convection this evening. Between the synoptic (soon to be combined with lake breeze) boundary near I-80 and convective outflow boundary downstate, the airmass is very unstable. Between these two boundaries, low level moisture hasn't mixed out as much and instability quite strong, with SPC mesoanalysis suggesting >3000 j/kg of MLCAPE. Broken line of supercells over eastern IA seems to be showing signs of cold cools amalgamating into a more cohesive singular cold pool, which would favor a forward propogating MCS developing. The intense HP supercell west of the Quad Cities could morph into the MCV with a developing MCS. It isn't clear if this developing MCS/potential bow echo would track more east along the synoptic/lake breeze front or more southeast east near the convective baroclinic zone. Given recent radar trends and the strongly unstable air mass between the two boundaries, with southeasterly winds in this area strengthening storm relative inflow, believe the threat of a severe thunderstorms with damaging winds is increasing this evening south of I-80. Will also need to watch for convection lighting up on the synoptic boundary ahead of the developing MCV for a potential hail threat, but bigger concern may be for training convection and flash flood threat with these storms. Confidence in the above scenario is still low, but am growing a bit more concerned given observational trends over the past hour. - Izzi && .SHORT TERM... Issued at 303 PM CDT Sun May 7 2023 Through Monday night... Strong to severe thunderstorms are firing up early this afternoon over central IA underneath an area of strong convergence found along the more-organized portion of the warm front that extends across our CWA. This is expected to evolve into what will become our severe weather potential for this evening. With the warm front continuing to organize further to the east and instability and moisture build south of the boundary, storms will continue to build along the front with storm initiation inching nearer to the CWA over the next several hours. The warm front, currently oriented roughly along the I-80 corridor, isn't expected to be displaced much between now and this evening meaning the track for storm initiation is laid directly across the central CWA. Storms looks to enter the CWA from the west sometime near 7PM and should start working into the metro closer to around 9PM. Meanwhile, the "pneumonia" cold front has made its way down the lake and has protruded several miles inland at this point and it continues to march inland with no sign of slowing down, at least for the next couple of hours. The intersection of these two boundaries continues to be the primary area of interest for severe convection later this evening. At this point, as much as 2,000+ J/kg of MLCAPE and 1-1.5" of PWAT have built up across much of the area south of the warm front. Lapse rates are forecast to be anywhere from 7 to 9 K/km from the base of the EML nearly all the way up to the equilibrium level. That being said, the forced ascent at the collision of the two fronts is expected to result in rapid thunderstorm development. Strong low level stability north of the warm front dampens the severe potential some, but some stronger elevated storms are certainly still possible. Storm motion is expected to be to the east, nearly parallel to the orientation of the warm front. With higher instability expected to trail the first push of thunderstorms this evening, the potential for training storms has become an increasing concern as it could lead to areas of flash flooding. Aside from flash flooding, hail is the biggest concern with these storms given the consistently steep lapse rates. A cold-pool driven wind potential may also be in the cards, moreso across southern portions of the CWA early tomorrow morning. A strong QLCS is progged to develop in southern Iowa late tonight and dive southeastward through central IL following the greater instability. Depending on how far north this system tracks, a push of severe winds may move through the southern CWA in the predawn hours of tomorrow morning. The severe potential lessens for the latter half of the night, though scattered storms may continue. With the front hanging in the area through tomorrow morning and the parent low forecast to move through in the afternoon, some stronger thunderstorms may also be possible tomorrow, primarily through the afternoon and for areas south of I-80. One last thing - temperatures continue to plummet in the wake of the lake cold front. This is expected to result in a blanket of marine fog over the lake this evening into tomorrow morning. The fog may bleed inland quite a bit given the onshore flow, but should be mostly restricted to lakeside counties. Doom && .LONG TERM... Issued at 121 PM CDT Sun May 7 2023 Tuesday through Sunday... Upper-level troughing currently off the Pacific Coast of British Colombia is expected to dig into southwestern United States Tuesday and Wednesday inducing height rises and indeed the development of an upper-level ridge in the central US. The Great Lakes will be at the inflection point of the upper-level wave train (e.g. eastern side of the ridge) and in close proximity to a slow-moving surface high pressure system. Accordingly, Tuesday through at least Thursday look beautiful with partly cloudy skies, highs in the mid to upper 70s (maybe even lower 80s?), light winds, and no precipitation. Onshore flow will support daily lake breezes keeping lakeshore locations some 10 to 15 degrees cooler. Overnight lows should range from the upper 50s to lower 60s. Even with quintessential model uncertainty beyond 5 days, ensemble guidance advertises aggregate southwestern US troughing shifting eastward toward the end of the week. When combined with anticyclonic return flow of moisture on the backside of the departing surface high, chances for showers and thunderstorms will return from Friday onward (though many hours will be dry). Borchardt && .AVIATION... For the 18Z TAFs... 1246 PM...Forecast concerns include... Lake breeze/wind shift early this afternoon. Chance of thunderstorms this evening and overnight. Mvfr cigs, possible ifr, overnight and Monday. Possible low clouds/fog near Lake Michigan this evening. A lake breeze is steadily moving inland currently and will be moving across ORD/MDW soon and adjusted timing earlier with this forecast. Winds are then expected to remain northeasterly for the rest of the period at the Chicago terminals. Much of the guidance is trending toward scattered thunderstorm development near and just southwest of the Chicago terminals early this evening. While there remains uncertainty for both coverage and location, these trends now support at least vicinity thunder mention with this forecast for this evening. Additional thunderstorms are possible overnight but confidence remains low enough to maintain prob mention. Showers or periods of light rain may continue through mid/late Monday morning and some showers may continue into Monday afternoon. Cooler air will spread inland from Lake Michigan later this afternoon into this evening which may result in some fog over the lake and low cigs near the lake. If these were to move inland, it would likely be after sunset but confidence remains low and have only included scattered mention for now. Trends will need to be monitored into this evening. Otherwise, prevailing cigs are expected to remain vfr into this evening with mvfr cigs developing overnight or toward daybreak Monday. Its possible cigs may lower to ifr on Monday but confidence is low. 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
254 PM CDT Sun May 7 2023
ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-082000-
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-
254 PM CDT Sun May 7 2023 /354 PM EDT Sun May 7 2023/
This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.
.DAY ONE...Tonight.
Weather hazards expected...
Elevated Thunderstorm Risk mainly near Interstate 80 with threats of:
Limited Hail Risk...up to ping pong ball size.
Limited Damaging Wind Risk...up to 65 mph.
Elevated Flooding Risk.
Limited Fog Risk.
DISCUSSION...
Scattered thunderstorms may develop near Interstate 80 after 7 PM.
While it is not a guarantee storms will form, those that do will
likely produce damaging hail, damaging winds, and torrential
downpours. Additional thunderstorms may move into central
Illinois after midnight.
.DAYS TWO THROUGH SEVEN...Monday through Saturday.
Monday...
Elevated Thunderstorm Risk, mainly south of Interstate 80.
Thursday through Saturday...
Limited Thunderstorm Risk.
DISCUSSION...
Additional thunderstorm chances exist Monday afternoon and
evening, mainly for central Illinois. The strongest storms may
produce damaging wind gusts and hail in addition to locally heavy
rainfall which could result in localized instances of flooding.
.SPOTTER INFORMATION STATEMENT...
Spotters may be needed near Interstate 80 this evening.
GENERAL STORM MOTION OF THE DAY:
Moving toward the east at 30 to 35 mph.
LMZ740>745-082000-
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-
254 PM CDT Sun May 7 2023
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...
Elevated Thunderstorm Risk...with an associated:
Limited hail risk...up to ping pong ball size.
Limited Fog Risk.
.DAYS TWO THROUGH SEVEN...Monday through Saturday.
Thursday through Saturday...
Limited Thunderstorm Risk.
Borchardt
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www.youtube.com/nwschicagoThe Chicago radar (KLOT), 56 km away, was scanning. The volume nearest the first event began at 23:28 UTC.
10 thunderstorm wind, 4 hail, 3 tornado, 1 dust storm, 1 flood, 1 high wind. Local standard time, as filed.
A video shared shows a landspout-type tornado kicking up dust in a field southwest of Route 1 and Route 17 near Grant Park. Time was estimated based on radar.
A photo shared shows a landspout tornado occurring along State Route 1/17 between Grant Park and Momence. The landspout threw a car into a ditch but did not cause any known damage to structures or trees.
A report of one inch diameter hail in Mendota was relayed by an off duty meteorologist. Time was estimated using radar.
A video shared shows a brief landspout tornado roughly three miles southwest of Serena. This landspout produced no known damage. The time, location, and track are all approximate.
A photo shared on social media showed hail up to 1.75 inches in diameter. Location was estimated. Time was based on the timestamp on the photo.
A report from mPING relayed one inch hail in Momence. Time was estimated based on radar.
A private weather station recorded 55-60 mph gusts for a more than 10 minute period with a peak of 62 mph.
A local fire official reported power lines and large tree limbs down in and around Lostant. Shingle and siding damage to some homes was also reported.
Crossing gates were reported snapped at a railroad crossing in Streator at North Bloomington Street in addition to some downed trees.
A trained spotter reported multiple road and parking signs that had been bent nearly 45 degrees near Kangley.
Pontiac communications center relayed a report of near-zero visibility due to blowing dust along I-39 near State Route 18. La Salle County emergency management also passed along several reports of near-zero visibility just north of Streator. Time was estimated based on radar.
A trained spotter reported hail with multiple hailstones being at least one inch in diameter. Time was estimated based on radar.
A few inches of standing water were reported on the westbound lane of US Route 52 near Serena.
Local media relayed a report of multiple power lines down and a damaged shed between Saunemin and Cullom. Time was estimated based on radar.
The Pontiac communications center relayed a report of tree damage along Route 116 in Cullom.
Multiple reports were received between roughly 10 and 11 PM CDT of trees downed by non-thunderstorm winds near Dixon.
Multiple live trees were reported down on Locust St and 5th St in Chatsworth. Time was estimated based on radar.
A COOP observer measured a 65 mph gust in Chatsworth. Numerous tree limbs were reported down including one about 4-5 inches in diameter than had fallen onto a car.
Numerous trees were reported downed in and around Piper City, including one that had fallen onto a house. Time was estimated based on radar.
A tree was reported snapped half way up and had fallen onto power lines in Paxton. Time was estimated based on data from nearby personal weather stations.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2023Every state in 2023This day in weather historyThe tornado archive for Illinois, 2023Warnings in Illinois, May 2023
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: 1100732, 1100733, 1100726, 1100734, 1100727, 1100728, 1100735, 1101087, 1101088, 1101089, 1102045, 1100729, 1102067, 1101090, 1101092, 1102904, 1101094, 1100736, 1101096, 1101098.