Severe thunderstorms developed across Iowa, Illinois and Missouri on Sunday, June 20th. Early in the morning, an MCS from the night before moved into our area along a stationary boundary and brought widespread rain showers to the area.
Every event with a place to put it. Tap one for its entry below.
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.
Severe thunderstorms developed across Iowa, Illinois and Missouri on Sunday, June 20th. Early in the morning, an MCS from the night before moved into our area along a stationary boundary and brought widespread rain showers to the area. This died off early in the day and then some clear skies moved in, providing some surface heating ahead of an approaching cold front. Ahead of this front, several discrete supercell thunderstorms formed, which posed a threat for tornadoes, hail, and severe wind gusts. Later in the day. these supercells generally grew upscale into a line of thunderstorms with embedded supercell structures. A tornado was spotted near Bernard, Iowa and lead to some damage to trees and farm outbuildings. Otherwise, severe winds reports and a few hail reports resulted from these storms. The severe threat continued eastward, and heavily impacted some suburbs of Chicago.
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 Jun 20, 5:33 PM CST, 47 minutes earlier.
Area Forecast Discussion National Weather Service Quad Cities IA IL 633 PM CDT Sun Jun 20 2021 ...00Z AVIATION UPDATE... .SYNOPSIS... Issued at 330 PM CDT Sun Jun 20 2021 Back edge of stratiform light rain was finally moving into our eastern counties, with sunshine in our western counties. The cloud cover has kept afternoon temperatures in the 70s but with strong June sunshine this should push readings into the forecast highs in the 80s. Meanwhile, deepening low pressure in southern MN has a cold front extending to northern KS, with a secondary cold front pushing across ND and nw MN. Pretty impressive front for mid June with north winds gusting to 40 mph in the northern Plains. Strong thunderstorms were developing ahead of this front in south-central MN. SPC mesoanalysis at 20z showed SBCAPE of 5000 J/kg in sw IA with effective bulk shear of 40-50 kt across northern IL, much of IA and southern MN. PWAT's were over 1.50 inches. && .SHORT TERM...(This Evening through Monday) ISSUED AT 330 PM CDT Sun Jun 20 2021 Key messages: 1) SPC has an enhanced risk for severe storms this evening for portions of the area. 2) Time frame for severe weather is 6 pm to midnight. 3) Cooler and much lower humidity on gusty northwest winds Monday. Tonight: CAM's indicates a few discrete supercells initially evolving into bowing segments ahead of strong cold front. Digging upper level trough providing large scale ascent, deepening cyclone and front pushing into an unstable, rich moisture warm sector should trigger severe storms. Golf ball size hail, damaging winds to 70 mph and a few tornadoes are all possible this evening. Cold front will sweep across the cwa overnight ending the storms and ushering cooler and less humid air on nw winds. Lows will range from the mid to upper 50s nw to the lower 60s se. Monday: Delightful day with below normal temperatures and very comfortable humidity levels, due to northwest flow aloft and Canadian high pressure building into the area. Northwest winds should also be gusting to 30 mph, adding to a fall-like feel to the day. Highs will be in the upper 60s to lower 70s with dewpoints in the 40s! .LONG TERM...(Monday Night through Sunday) ISSUED AT 330 PM CDT Sun Jun 20 2021 Monday night: Clear and cool with light winds with high pressure ridge settling over the cwa. Lows will be in the mid 40s to around 50. Tuesday: Another nice day with highs in the 70s but with light southwest winds. Wednesday through Friday: High pressure shifts east with return flow of warm/moist airmass. Heights rise with zonal flow across the area. This pattern recognition in June suggests periodic rounds of thunderstorms, possibly severe, along with heavy rainfall. However, it is too early for details. Highs well into the 80s to near 90, with lows well into the 60s to lower 70s. Next weekend: Cold front moves through with below normal temperatures and mainly dry weather. Highs near 80 with lows in the 50s to around 60. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) ISSUED AT 633 PM CDT Sun Jun 20 2021 Scattered strong to severe storms out ahead of a cold front may impact the terminals this evening with very heavy rain, strong winds and hail. However, coverage is questionable and the tempo groups for thunderstorms at the terminals may be overdone. Following the cold front later this evening, winds will become gusty from the northwest with a period of MVFR stratus possible overnight. Monday will be predominantly VFR with gusty northwest winds. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...Haase SHORT TERM...Haase LONG TERM...Haase AVIATION...Sheets
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 242 PM CDT Sun Jun 20 2021 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-211945- 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- 242 PM CDT Sun Jun 20 2021 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...THIS AFTERNOON AND TONIGHT The Storm Prediction Center has an Enhanced Risk for severe storms across portions of eastern Iowa and northwest and western Illinois. A strong cold front will approach the area this evening. Severe thunderstorms are likely with super cells and bowing segments. Large hail to golf ball size, damaging winds to 75 mph and a few tornadoes are all threats. The main time frame is this evening from 6 pm to midnight. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY There is a chance for thunderstorms Tuesday night through Saturday. It is too soon to determine the risk for severe weather. .SPOTTER INFORMATION STATEMENT... Spotter activation will be needed especially this evening. Haase
Special Weather Statement
National Weather Service Quad Cities IA/IL
622 PM CDT Sun Jun 20 2021
IAC019-055-210015-
Buchanan-Delaware-
622 PM CDT Sun Jun 20 2021
...A STRONG THUNDERSTORM WILL AFFECT BUCHANAN AND DELAWARE COUNTIES
UNTIL 715 PM CDT...
At 622 PM CDT, a strong thunderstorm was located over Hazleton, or
near Oelwein, moving east at 40 mph.
Winds in excess of 40 mph and pea size hail are possible with this
storm.
Locations impacted include...
Independence, Manchester, Dyersville, Jesup, Fairbank, Edgewood,
Winthrop, Hazleton, Earlville, Quasqueton, Lamont, Delhi, Colesburg,
Greeley, Aurora, Dundee, Delaware, Masonville, Stanley and Oneida.
Torrential rainfall is also occurring with this storm. Minor flooding
of low lying areas, creeks, streams and urban areas is possible. If
you encounter water over a roadway, do not drive through it.
LAT...LON 4242 9113 4238 9206 4247 9206 4247 9208
4264 9208 4265 9114
TIME...MOT...LOC 2322Z 267DEG 45KT 4260 9189
RP KinneySpecial Weather Statement
National Weather Service Quad Cities IA/IL
653 PM CDT Sun Jun 20 2021
IAC011-019-055-061-113-210045-
Buchanan-Dubuque-Benton-Delaware-Linn-
653 PM CDT Sun Jun 20 2021
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT BUCHANAN...NORTHWESTERN
DUBUQUE...NORTHERN BENTON...DELAWARE AND NORTHERN LINN COUNTIES UNTIL
745 PM CDT...
At 653 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Colesburg to near Rowley. Movement
was east southeast at 35 mph.
Winds in excess of 40 mph and pea size hail are possible with these
storms.
Locations impacted include...
Dubuque, Independence, Vinton, Manchester, Asbury, Dyersville, Jesup,
Center Point, Epworth, Farley, Urbana, Dysart, Peosta, Winthrop,
Hazleton, Earlville, Walker, Coggon, Hopkinton and Quasqueton.
This includes Interstate 380 between mile markers 35 and 55.
Torrential rainfall is also occurring with these storms. Minor
flooding of low lying areas, creeks, streams and urban areas is
possible. If you encounter water over a roadway, do not drive through
it.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4264 9071 4254 9064 4250 9065 4200 9230
4230 9230 4230 9206 4261 9208 4265 9090
4268 9089
TIME...MOT...LOC 2353Z 290DEG 31KT 4260 9124 4237 9194
RP KinneySpecial Weather Statement
National Weather Service Quad Cities IA/IL
658 PM CDT Sun Jun 20 2021
IAC095-107-210030-
Keokuk-Iowa-
658 PM CDT Sun Jun 20 2021
...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN KEOKUK AND
SOUTHWESTERN IOWA COUNTIES UNTIL 730 PM CDT...
At 658 PM CDT, a strong thunderstorm was located near Montezuma,
moving east at 30 mph.
Winds in excess of 40 mph and half inch hail are possible with this
storm.
Locations impacted include...
Williamsburg, North English, South English, Parnell, Millersburg and
Lake Iowa Park.
This includes Interstate 80 in Iowa between mile markers 205 and 222.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4151 9230 4172 9230 4170 9196 4143 9201
4151 9240
TIME...MOT...LOC 2358Z 277DEG 26KT 4161 9241
SpeckPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
714 PM CDT SUN JUN 20 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0708 PM HAIL 3 NE MANCHESTER AIRPORT 42.53N 91.46W
06/20/2021 E0.25 INCH DELAWARE IA EMERGENCY MNGR
ALSO 40-45 MPH WIND GUST.
&&The Quad Cities radar (KDVN), 122 km away, was scanning. The volume nearest the first event began at 00:18 UTC.
2 thunderstorm wind, 2 tornado, 1 hail. Local standard time, as filed.
Tree branches were blown down, resulting in city needing to clear up.
A tornado developed just west of Garry Owen in northwest Jackson County, and moved northeast along an intermittent 3 mile path through farm fields, lifting east of Bernard in southern Dubuque County. The tornado caused tree damage, and extensive damage to outbuildings at 4 farmsteads. The tornado was rated EF1, with maximum winds estimated at 90 to 100 mph, and was on the ground for about 6 minutes. There were no injuries. Assistance provided by Dubuque and Jackson County Emergency Management is much appreciated.
A tornado developed just west of Garry Owen in northwest Jackson County, and moved northeast along an intermittent 3 mile path through farm fields, lifting east of Bernard in southern Dubuque County. The tornado caused tree damage, and extensive damage to outbuildings at 4 farmsteads. The tornado was rated EF1, with maximum winds estimated at 90 to 100 mph, and was on the ground for about 6 minutes. There were no injuries. Assistance provided by Dubuque and Jackson County Emergency Management is much appreciated.
CBS2 Meteorologist storm chasing reported lots of quarter size hail and few half dollar size.
A few large limbs blown down, along with the roof blown off a baseball clubhouse.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2021Every state in 2021This day in weather historyThe tornado archive for Iowa, 2021Warnings in Iowa, 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: 957340, 957342, 957343, 957339, 957341.