A surface low with an attendant warm front moved across eastern Iowa into northwest Illinois. This low system brought widespread showers and thunderstorms to the area.
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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 DVN wrote it up.
A surface low with an attendant warm front moved across eastern Iowa into northwest Illinois. This low system brought widespread showers and thunderstorms to the area. Overall widespread rainfall of 1 to 3 inches fell. Severe thunderstorms also developed during the afternoon hours. These thunderstorms produced damaging wind gusts along the Interstate 80 corridor in northwest Illinois.
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 Quad Cities, IA wrote its last area forecast discussion before the first event at May 20, 11:32 AM CST, 1 hour 28 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Quad Cities IA IL 1232 PM CDT Tue May 20 2025 .KEY MESSAGES... - Windy conditions will be seen this morning with sustained east winds of 20 to 30 mph, gusting up to 45 mph at times. - A conditional severe risk (level 1 out of 5) is in place this afternoon along/south of Interstate 80 and east of U.S. highway 218. The primary risks look to be damaging winds and tornadoes. - Much cooler than normal temperatures will be seen across the area Wednesday and Thursday. && .SHORT TERM /THROUGH TONIGHT/... Issued at 304 AM CDT Tue May 20 2025 The large rain shield across the area with embedded thunderstorms will slowly move north through the morning. Breaks in the clouds should then develop south of I-80 that will allow differential heating to occur. Some diurnally driven isolated convective cells will probably develop by early afternoon. However, there is a respectable vort max that will catch up to the attendant surface low that will be responsible for the more substantial convection this afternoon. That raises the question regarding the severe potential. The differential heating will help initiate the diurnal storms and the associated surface low and upper level vort max will help strengthen them. Based on output from the CAMs, the overall scenario that is being suggested is low-topped supercells (i.e. storm tops not much above 30 kft). With progged freezing level heights of 10-11 kft, there will probably be a fair amount of small hail (<0.75 inch) associated with the storms. The strongest storms and associated updrafts would be capable of producing 1 inch hail. What is interesting is the progged corridor running from Keokuk, IA up to the northeast of DVN/MLI that has non-supercell tornado parameter numbers greater than 3. Numbers this high suggest that any horizontal vorticity roll would get quickly stretched if pulled into an updraft producing a tornado. The 1-5 PM time frame looks to be the most favored for any severe but initiation/continuation before/after those times is possible. Thus a padded 12-6 PM time frame is more realistic. The area of concern looks to be along/south of the I-80 corridor and generally east of U.S. highway 218. The primary severe risks look to be damaging winds and tornadoes. These will be most likely along any mesoscale boundary and near the triple point of the passing surface low. Tonight the diurnal convection will dissipate with sunset but the proximity of the upper level system suggests very isolated convection may persist well past sunset. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 304 AM CDT Tue May 20 2025 Wednesday through Thursday Assessment...very high (>90%) confidence of cooler than normal temperatures. The proximity of the upper low combined with steep mid-level lapse rates will keep plenty of clouds across the area on Wednesday with clouds slowly breaking up Thursday. As a result, temperatures will be well below normal. Wrap around rain will be seen across the area Wednesday into Wednesday evening as the storm system slowly exits the area. The best chances for rain will be north of I-80 with little if any rain south of an Ottumwa, IA to Galesburg, IL line. Rain may linger into late Wednesday night across the area. On Thursday, mid-level lapse rates remain quite steep with cold air aloft. Thus diurnal clouds are expected to develop during the day and produce some isolated showers, mainly north of I-80. Thursday night through Friday night Assessment...High (>80%) confidence on cooler than normal temperatures The model consensus has cool Canadian high pressure moving through the Midwest bringing cooler than normal and dry conditions to the area. Saturday through Monday Assessment...Medium (40-60%) confidence on precip for Saturday and Saturday night. Low (<25%) confidence beyond Saturday night Although there are differences in the details, the global models general show boundaries, either at the surface or aloft, that a storm system will follow through the Midwest Saturday/Saturday night. Subtle timing differences between the solutions have resulted in somewhat lower pops but the model consensus of 20-50 percent rain chances look reasonable this far out. The bigger questions is what happens Sunday into Monday. The CMC slows the Saturday system to a crawl and has it lingering over the Midwest for the remainder of the holiday weekend. The ECMWF and ICON models are essentially dry Sunday into Monday. The GFS/UKMET have a very weak system right on the heels of the Saturday system that has rain for Sunday/Sunday night. The UKMET has a tertiary system, albeit very weak, in the cyclonic flow aloft moving through the area on Monday producing some rain while the GFS is dry. Some but certainly not a majority of the ensemble members from the global models linger precipitation Sunday through Monday across the area. Thus the model consensus is biased by the CMC/UKMET solutions and the ensembles of the global models in keeping 30-40 percent rain chances Sunday through Monday across the area. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1214 PM CDT Tue May 20 2025 A warm/quasistationary front near I-80 will serve as a demarcation between VFR and MVFR/IFR ceilings, with the higher ceilings to the south. As the surface low pressure system lifts through the IA/IL/MO tri-state region through the afternoon, prolific scattered thunderstorms will continue. Depending on confidence at each the TAF site, PROB30 or TEMPO groups were added to highlight the period of greatest concern for lightning; the strongest storms will be capable of brief erratic winds and small hail. Through the afternoon, winds will primarily blow from the east along and north of the warm front, and from the south further south. This evening into tonight, those winds will veer to west-northwest, picking back up and featuring some gusts after around 14/15z (9-10am) Wednesday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && SHORT TERM...08 LONG TERM...08 AVIATION...Bumgardner
Hazardous Weather Outlook...CORRECTED National Weather Service Quad Cities IA IL 329 AM CDT Tue May 20 2025 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-210830- Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson- Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson- Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll- Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson- Warren-Hancock-McDonough-Scotland-Clark- 329 AM CDT Tue May 20 2025 This Hazardous Weather Outlook is for portions of north central Illinois...northwest Illinois...west central Illinois...east central Iowa...northeast Iowa...southeast Iowa and northeast Missouri. .DAY ONE...TODAY AND TONIGHT There is a Marginal to Slight Risk (level 1 and 2 out of 5 risk) for severe storms this afternoon. The risk area is generally south of Highway 30 and east of Highway 218. Damaging winds and tornadoes are the primary risks. Localized flooding is also possible. Non-thunderstorm winds may gust up to 45 mph at times this morning. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible along and south of Interstate 80 and east of Highway 218 this afternoon. GENERAL STORM MOTION OF THE DAY: To the east northeast at 20 mph.
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
923 AM CDT Tue May 20 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0649 AM Rain 2 NNE Credit Island 41.52N 90.60W
05/20/2025 M2.04 Inch Scott IA Trained Spotter
Corrects previous rain report from 2 NNE
Credit Island. 24 hour rainfall.
&&
TJGPreliminary Local Storm Report
National Weather Service Quad Cities IA IL
945 AM CDT Tue May 20 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0945 AM Rain 2 NNW North Liberty 41.76N 91.62W
05/20/2025 M2.10 Inch Johnson IA Trained Spotter
Current storm total rainfall.
&&
TJGPreliminary Local Storm Report
National Weather Service Quad Cities IA IL
1031 AM CDT Tue May 20 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1030 AM Rain 2 SW Saint Donatus 42.35N 90.57W
05/20/2025 M1.53 Inch Jackson IA Trained Spotter
Storm total rainfall so far.
&&
TJGPreliminary Local Storm Report
National Weather Service Quad Cities IA IL
1115 AM CDT Tue May 20 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1114 AM Rain Walcott 41.59N 90.77W
05/20/2025 M1.75 Inch Scott IA Public
Storm total rainfall.
&&
TJGPreliminary Local Storm Report
National Weather Service Quad Cities IA IL
1133 AM CDT Tue May 20 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1130 AM Rain 1 SSW Geneseo 41.44N 90.16W
05/20/2025 M1.16 Inch Henry IL Trained Spotter
Storm total.
&&
JRBPreliminary Local Storm Report
National Weather Service Quad Cities IA IL
1145 AM CDT Tue May 20 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1145 AM Rain 1 ENE Green River 41.47N 90.32W
05/20/2025 M1.30 Inch Henry IL Trained Spotter
Storm total.
&&
JRBThe Quad Cities radar (KDVN), 34 km away, was scanning. The volume nearest the first event began at 19:00 UTC.
4 thunderstorm wind. Local standard time, as filed.
A public report of two 2 to 3 inch diameter tree branches snapped by thunderstorm winds.
A trained spotter report that a 7 inch diameter tree was uprooted this afternoon. The time of the event was estimated using radar.
A public report of a few very large tree branches down. The time of the event was estimated using radar.
A public report of a 2 inch tree limb knocked down by thunderstorm wind. The time of the event was estimated using radar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2025Every state in 2025This day in weather historyWarnings in Illinois, May 2025
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: 1259759, 1259761, 1259766, 1259768.