A disturbance moving across the eastern Iowa on the 27th produced slow moving showers and thunderstorms across the area. This led to flash flooding in northwest Johnson 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 DVN wrote it up.
A disturbance moving across the eastern Iowa on the 27th produced slow moving showers and thunderstorms across the area. This led to flash flooding in northwest Johnson County.
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 27, 1:39 PM CST, 1 hour 31 minutes earlier.
Area Forecast Discussion National Weather Service Quad Cities IA IL 239 PM CDT Sat Jun 27 2020 .SYNOPSIS... Issued at 238 PM CDT Sat Jun 27 2020 A cluster of showers and isolated storms have developed in portions of the eastern IA. SPC mesoscale analysis indicated no shear but CAPE has built up to 3000 J/kg. PWAT's were 1.5+ inches in our south half. Therefore, pulse storms will occur with rather slow moving storms with torrential rainfall. Isolated strong wind gusts are possible in stronger pulse storms with SPC having a marginal risk for severe near and south of I-80. Freezing levels are 14-15k ft so hail threat appears low. Stationary front extended from near Omaha to Milwaukee. && .SHORT TERM...(This Evening through Sunday) ISSUED AT 238 PM CDT Sat Jun 27 2020 Isolated to scattered showers and storms expected in the short term with little if any shear but plenty of moisture available for heavy rain in pulse storms. A marginal risk for severe storms is in place for much of the cwa through Sunday. The main risk will be isolated strong wind gusts in heavier storms. I will maintain 30-40 pct pops through Sunday. Lows around 70. Highs well in the 80s to near 90. .LONG TERM...(Sunday Night through Saturday) ISSUED AT 238 PM CDT Sat Jun 27 2020 Key Message: Mainly Unchanged 1) Seasonally normal summertime heat and humidity will persist, with daily chances for showers and storms 2) Temperatures for the most part will be between 85 and 90 degrees through next Saturday, with heat indices reaching into the low to mid 90s, with a few isolated bouts of upper 90s possible Monday PM. Forecast details... The pattern will remain fairly stagnant; with troughing east and west and ridging over the central portion of the country. Forecast wind speeds all week are essentially between calm and 10 MPH, at times maybe up to 15 MPH. Seasonal heat and humidity levels will persist throughout the week with highs in the mid 80s to around 90 in some places. Dew points will be in the upper 60s to mid 70s. Daily afternoon and early evening heat index values will peak in the lower to mid 90s. Given the moisture-laden air mass in place, diurnal heating alone or any surface boundary or remnant outflow boundary will be sufficient for the development of a shower or storm. Therefore, the forecast blend has daily chances (mainly isolated to scattered... 20 to 50) for convection through much of the extended. Currently the forecast blend has the best chances (60 to 70 likely pops) for Tuesday afternoon when some models bring an upper level wave over the area. Despite the daily precip chances, there will be several dry hours to be had. Also of note is that any storm that does develop will have the potential to produce brief heavy rainfall. && .AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon) ISSUED AT 1255 PM CDT Sat Jun 27 2020 Warm, moist and unstable airmass will create isolated to scattered showers and thunderstorms, especially this afternoon and evening. Confidence is indicating that it may impact KBRL but there is still some uncertainty further north so for now have kept taf dry. Periods of MVFR and IFR ceilings and visibilties are possible in any thunderstorms but VFR conds will prevail outside of storms. Winds will be light and vrbl. && .HYDROLOGY... Issued at 1048 AM CDT Sat Jun 27 2020 Upgraded the Flood Watches on the Mississippi River at Gladstone and Burlington to Flood Warnings this morning. Confidence has increased that they will at least surpass flood stage within the next 42 to 54 hours, due in part to all ensemble members pointing in that direction. Both locations are currently forecast to crest about 3 to 6 inches above their respective flood stages. Locations downstream will need to be monitored for future rises and possible flooding. At Keithsburg, there remains some uncertainty in routed flow, and thus have maintained the Flood Watch for this site. Tributary river forecasts this morning have remained essentially unchanged. Minor to moderate flooding continues on parts of the Cedar and Iowa rivers, and Major Flooding is still forecast for the Wapsipinicon River at De Witt. An active pattern will linger over the region for the next week or so. While widespread heavy rains are not anticipated at this time, some locally heavy rains will be possible, which may result in continued or new flooding concerns. It should also be noted that there will be plenty of dry, rain free, hours as well. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...Haase SHORT TERM...Haase LONG TERM...14 AVIATION...Haase HYDROLOGY...14
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 256 PM CDT Sat Jun 27 2020 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-282000- 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- 256 PM CDT Sat Jun 27 2020 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 Scattered thunderstorms can be expected this afternoon and evening. The main risk from these storms are torrential rainfall and strong wind gusts. There is a marginal risk for severe storms near and south of Interstate 80. Area rivers are experiencing flooding. Please see the latest Flood Statements and Flood Warnings for details. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY Scattered thunderstorms are again expected on Sunday. There is a marginal risk for severe storms across the entire outlook area. The main risks will be torrential rainfall and strong wind gusts. There will be periodic storm chances next week, with plenty of dry hours as well. It is too early to assess any potential for severe weather. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated this afternoon or tonight. Haase
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1040 AM CDT SAT JUN 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1038 AM HEAVY RAIN 1 ENE FAIRFIELD MUNICIP 41.05N 91.96W
06/27/2020 M2.40 INCH JEFFERSON IA TRAINED SPOTTER
RAINFALL SINCE LAST EVENING.
&&
HAASESpecial Weather Statement
National Weather Service Quad Cities IA/IL
248 PM CDT Sat Jun 27 2020
IAC107-183-272045-
Keokuk-Washington-
248 PM CDT Sat Jun 27 2020
...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT KEOKUK AND WASHINGTON
COUNTIES UNTIL 345 PM CDT...
At 244 PM CDT, scattered thunderstorms were located across Keokuk
and Washington counties. These storms were nearly stationary and
were producing torrential rainfall in spots. Portions of these two
counties received 3 to 6 inches of rainfall last night and the
ground is saturated. If a storm is persistent in one area then a
flash flood warning may need to be issued. Be alert for rising water.
Locations impacted include...
Washington, Sigourney, Kalona, Wellman, Riverside, Hedrick, Brighton,
What Cheer, Richland, Ainsworth, Delta, Crawfordsville, Keswick,
South English, Harper, Martinsburg, Kinross, Hayesville, Coppock and
Richmond.
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 4151 9241 4151 9153 4150 9151 4147 9151
4141 9148 4116 9149 4116 9241
TIME...MOT...LOC 1944Z 224DEG 10KT 4128 9155
HaaseSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE Quad Cities IA/IL 328 PM CDT Sat Jun 27 2020 IAZ063-064-272130- Iowa-Johnson- 328 PM CDT Sat Jun 27 2020 ...A LINE OF THUNDERSTORMS will affect northern Johnson and southeastern Iowa Counties... At 324 PM CDT...A LINE OF thunderstorms was located along a line extending from Williamsburg to North Liberty. The storms were nearly stationary and were producing torrential rainfall in spots. In addition, several funnel clouds have been reported. LOCATIONS IMPACTED INCLUDE... Iowa City, Coralville, North Liberty, Williamsburg, Solon, Tiffin, University Heights, Oxford, Parnell, Oakdale, Lake Macbride State Park, Conroy, Newport, Windham, Sugar Bottom Camp Ground, Johnson County Fairgrounds, F.W. Kent Park, West Overlook, Coralville Lake Dam Complex and Iowa City Municipal Airport. 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. Funnel clouds of this nature are short lived and rarely touch the ground. However, if you notice one approaching the ground, move indoors to a place of safety. The National Weather Service will continue to closely monitor the situation. Please forward reports of funnel cloud sightings to the nearest law enforcement agency for relay to the National Weather Service. LAT...LON 4175 9206 4184 9148 4164 9138 4155 9206 TIME...MOT...LOC 2024Z 180DEG 0KT 4173 9152 4167 9202 Haase
Special Weather Statement
National Weather Service Quad Cities IA/IL
348 PM CDT Sat Jun 27 2020
ILC011-155-272115-
Putnam-Bureau-
348 PM CDT Sat Jun 27 2020
...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN PUTNAM AND EAST
CENTRAL BUREAU COUNTIES UNTIL 415 PM CDT...
At 347 PM CDT, a strong thunderstorm was located over Spring Valley,
or over Peru, moving east at 30 mph.
Winds in excess of 40 mph are possible with this storm.
Locations impacted include...
Spring Valley, DePue, Ladd, Dalzell, Cherry, Ottville and Spring
Valley Airport.
This includes Interstate 80 in Illinois between mile markers 69 and
73.
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.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
LAT...LON 4127 8918 4132 8929 4143 8921 4141 8916
4127 8916
TIME...MOT...LOC 2047Z 273DEG 10KT 4133 8918
HaasePRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
350 PM CDT SAT JUN 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0345 PM HEAVY RAIN 1 SSW NORTH LIBERTY 41.73N 91.62W
06/27/2020 M1.52 INCH JOHNSON IA TRAINED SPOTTER
IN THE PAST HOUR.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
408 PM CDT SAT JUN 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM HEAVY RAIN TIFFIN 41.71N 91.67W
06/27/2020 M3.00 INCH JOHNSON IA TRAINED SPOTTER
OCCURRED IN 1 HOUR.
&&The Quad Cities radar (KDVN), 91 km away, was scanning. The volume nearest the first event began at 21:12 UTC.
1 flash flood. Local standard time, as filed.
Law enforcement reported 4 inch deep water flowing across Highway 6 in Tiffin, and water 10 inches deep on Railroad Street. Trained spotters reported 3 inches of rain in 1 hour in Tiffin.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2020Every state in 2020This day in weather historyWarnings in Iowa, June 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: 898889.