Scattered showers and isolated thunderstorms developed ahead of a cold front that dropped southward into the area August 30th. A warm and humid air mass was in place that helped to produce these showers and thunderstorms.
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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.
Scattered showers and isolated thunderstorms developed ahead of a cold front that dropped southward into the area August 30th. A warm and humid air mass was in place that helped to produce these showers and thunderstorms. The stronger showers and thunderstorms were capable of producing very heavy rainfall in a short period of time with some areas picking up a half an inch of rain in under 20 minutes. This lead to flash flooding in the city of Geneseo in Henry 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 Aug 30, 5:40 AM CST, 2 hours 20 minutes earlier.
Area Forecast Discussion National Weather Service Quad Cities IA IL 640 AM CDT TUE AUG 30 2016 ...AVIATION UPDATE... .SYNOPSIS... Issued at 334 AM CDT Tue Aug 30 2016 Another warm and humid night across the region with scattered, slow moving thunderstorms producing heavy rainfall rates over the area. Radar showed this activity clustered mainly in two areas as of 3 am: one over NW IL from around Galesburg to Rockford, and the other just west of the highway 218 corridor from Washington to Iowa City. This elevated convection appeared to be due to weak impulses gliding along the edge of the upper high over the mid MS River and Ohio River valleys, interacting with elevated instability and high PW lingering over the region. Additional storms were over southern MN, drifting south with the help of a cold front that will drop south through the forecast area tonight, bringing an end to what has been a long stretch of humid and very wet weather over the area. && .SHORT TERM...(Today and Tonight) ISSUED AT 334 AM CDT Tue Aug 30 2016 Forecast focus remains on scattered thunderstorms with heavy rainfall, which will be likely over the area again today. Until the cold front moves through tonight, persistence will be the rule with a similar airmass and synoptic setup that has been over the region the past several days. Will thus have another day with largely pulse type, slow moving showers and thunderstorms capable of very heavy rainfall rates and flash flooding where storms become nearly stationary due to outflow boundary interactions. Also, there will the potential for more funnel clouds where rapidly developing convection occurs along boundary interactions. Have gone with high chance to likely pops for today, with higher values in the south where models depict greater coverage. With the more widespread convection and cloud cover, temperatures should be slightly cooler in most areas with highs in the lower to mid 80s. Dewpoints in the lower 70s will however lead to another very humid day. Tonight, the cold front, likely entering southern WI into NE IA in the evening, will drop southeast through the area overnight, ending the showers and thunderstorms from north to south. The cooler, drier airmass that follows will lead to lows in the upper 50s in the far north to the upper 60s in the far south. .LONG TERM...(Wednesday through Monday) ISSUED AT 334 AM CDT Tue Aug 30 2016 Main forecast concern for the long term are the chances for rain and thunderstorms across the south on Wednesday afternoon and then a return to the same pattern we have been in as of late, late in the holiday weekend. Guidance has sped the timing of fropa up for Wednesday. Agreement between all of the guidance is that the front will be through the area by 18Z Wednesday. As such, have split 12Z to 00Z Wednesday POPs into 6 hour blocks with the first six seeing a slight chance for rain and storms across the extreme southern CWA Some models linger the moisture behind the front. Think this is overdone with the almost due north flow. HIRES cams depict that with fropa, the moisture is quickly ushered out of the area. Wednesday night through Sunday morning look like a good glimpse of early fall with no chances of rain, low humidity and highs in the 70s. Canadian high pressure still forecast to settle across the area and lead to more palatable weather. Late in the weekend, Sunday and into next week, few changes from previously forecasts. SW flow begins and ushers in higher humidity and higher PWATs. Ripples in the flow will lead to showers and thunderstorms. Past this, it appears that the ECMWF and GFS predict more of the same, boundary across the area with showers and thunderstorms. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning) ISSUED AT 640 AM CDT Tue Aug 30 2016 Scattered showers and thunderstorms will continue today into this evening across the area. Early this morning, fog and low cigs may result in IFR conditions, mainly before 14z. A cool front dropping south out of MN will likely trigger the next round of organized thunderstorms beginning late this morning, which was handled with TEMPO groups. Beyond, convective trends are low confidence with storms possibly lasting into the evening at CID and MLI, and overnight at BRL. All sites could see some developing fog and potential low ceilings overnight, but confidence in this part of the forecast was low and thus only MVFR conditions were included. && .HYDROLOGY... Issued at 334 AM CDT Tue Aug 30 2016 Overall changes from previous issuance are that the watch at Keithsburg has been changed to a warning. With a consistent forecast and less than 24 hours until flood stage reached, decided to go with a warning. Otherwise nothing has changed from previous discussion. Previous discussion is attached for brevity: Issued at 300 PM CDT Mon Aug 29 2016 Flood Warnings: Steady river level rises the past several days have increased confidence in reaching minor flood stage at three sites. Flood Watches were upgraded to Flood Warnings at Conesville on the Cedar River, and at Gladstone and Burlington on the Mississippi River. Flood Watches: Lower confidence exists for other sites where the forecast to reach minor flood stage is beyond 24 hours. Issued a new Flood Watch for New Boston LD17, both on the Mississippi River. On the Wapsipinicon River, decided not to issue a watch for Dewitt because we are anticipating a river level fall to occur before the rise that may bring it to minor flood stage toward the end of this week. Uttech && .DVN Watches/Warnings/Advisories... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...Sheets SHORT TERM...Sheets LONG TERM...Gibbs AVIATION...Sheets HYDROLOGY...Gibbs/Uttech
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 416 AM CDT TUE AUG 30 2016 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-310930- 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- 416 AM CDT TUE AUG 30 2016 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 THUNDERSTORMS ARE LIKELY ACROSS THE OUTLOOK AREA TODAY AND TONIGHT. THE GREATEST THREAT FROM THESE STORMS WILL BE HEAVY RAINFALL...WHICH MAY LEAD TO LOCALIZED FLASH FLOODING. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THERE IS A CHANCE FOR SHOWERS AND THUNDERSTORMS WEDNESDAY MORNING ACROSS THE AREA. THE MAIN THREATS FROM THESE STORMS WOULD BE LIGHTNING AND LOCALLY HEAVY RAINFALL. THERE IS CHANCE FOR SHOWERS AND THUNDERSTORMS SUNDAY THROUGH MONDAY. AT THIS TIME SEVERE WEATHER IS NOT ANTICIPATED. FLOOD WARNING AND WATCHES ARE IN EFFECT FOR PORTIONS OF THE AREA. PLEASE SEE THE LATEST FLOOD STATEMENTS AND WARNINGS FOR DETAILS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED TODAY OR TONIGHT. HOWEVER...REPORTS OF HEAVY RAINFALL OR FLASH FLOODING WILL BE APPRECIATED. SHEETS/GIBBS
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA/IL
347 AM CDT TUE AUG 30 2016
ILC011-155-300945-
BUREAU-PUTNAM-
347 AM CDT TUE AUG 30 2016
...STRONG THUNDERSTORMS WITH GUSTY WINDS AND TORRENTIAL RAINFALL
WILL AFFECT BUREAU AND PUTNAM COUNTIES UNTIL 445 AM CDT...
AT 342 AM CDT...A LINE OF STRONG THUNDERSTORM WAS LOCATED FROM
WALNUT TO PROVIDENCE...MOVING EAST AT 30 MPH. THESE STORMS WERE
PRODUCING VERY HEAVY RAINFALL AND CAPABLE OF WIND GUSTS OVER 40 MPH.
RAINFALL 1 TO 2 INCHES IN LESS THAN HOUR IS LIKELY WITH THESE
STORMS.
LOCATIONS IMPACTED INCLUDE...
PRINCETON...HENNEPIN...SPRING VALLEY...HENRY...DEPUE...GRANVILLE...
WALNUT...LADD...WYANET...SHEFFIELD...TISKILWA...LA MOILLE...
DALZELL...BUDA...BUREAU JUNCTION...MCNABB...PUTNAM...MARK...
OHIO AND CHERRY.
THIS INCLUDES INTERSTATE 80 IN ILLINOIS BETWEEN MILE MARKERS 38 AND
72.
TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.
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 4110 8936 4112 8934 4115 8933 4115 8958
4116 8964 4123 8964 4124 8983 4158 8983
4159 8917 4111 8916
TIME...MOT...LOC 0842Z 289DEG 23KT 4135 8959
SHEETSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
557 AM CDT TUE AUG 30 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0555 AM HEAVY RAIN N WELLMAN 41.47N 91.84W
08/30/2016 M1.35 INCH WASHINGTON IA TRAINED SPOTTER
24-HR STORM TOTAL
&&
PETERSSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA/IL
656 AM CDT TUE AUG 30 2016
ILC011-073-155-301245-
HENRY-BUREAU-PUTNAM-
656 AM CDT TUE AUG 30 2016
...A STRONG THUNDERSTORM WITH HEAVY RAINFALL WILL AFFECT EASTERN
HENRY...BUREAU AND PUTNAM COUNTIES UNTIL 745 AM CDT...
AT 652 AM CDT...A STRONG THUNDERSTORM WAS LOCATED OVER ATKINSON...OR
12 MILES NORTHEAST OF CAMBRIDGE...MOVING EAST AT 25 MPH.
THIS STORM WAS PRODUCING VERY HEAVY RAIN...WITH AMOUNTS OVER 1 INCH
IN LESS THAN 15 MINUTES POSSIBLE.
LOCATIONS IMPACTED INCLUDE...
KEWANEE...PRINCETON...HENNEPIN...SPRING VALLEY...GALVA...HENRY...
DEPUE...GRANVILLE...WALNUT...LADD...WYANET...ATKINSON...SHEFFIELD...
ANNAWAN...TISKILWA...LA MOILLE...DALZELL...BUDA...
BUREAU JUNCTION AND MCNABB.
THIS INCLUDES INTERSTATE 80 IN ILLINOIS BETWEEN MILE MARKERS 23 AND
72.
TORRENTIAL RAINFALL IS OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING AND POOR VISIBILITY FOR MOTORISTS. DO NOT DRIVE
YOUR VEHICLE THROUGH FLOODED ROADWAYS.
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 4110 8936 4112 8934 4115 8933 4115 8964
4123 8964 4123 8987 4115 8987 4115 9010
4158 9010 4158 8917 4110 8916
TIME...MOT...LOC 1152Z 273DEG 21KT 4143 9002
SHEETSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
720 AM CDT TUE AUG 30 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0600 AM HEAVY RAIN 3 NE MUSCATINE 41.46N 91.03W
08/30/2016 M2.10 INCH MUSCATINE IA TRAINED SPOTTER
FELL IN 40 MINUTES ENDING 540 AM THIS MORNING.
&&
DLSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
825 AM CDT TUE AUG 30 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0600 AM HEAVY RAIN DEWITT 41.82N 90.55W
08/30/2016 M1.82 INCH CLINTON IA CO-OP OBSERVER
24-HR TOTAL.
0700 AM HEAVY RAIN 3 W DAVENPORT 41.56N 90.66W
08/30/2016 M1.25 INCH SCOTT IA COCORAHS
24-HR TOTAL.
0700 AM HEAVY RAIN 1 WNW DEWITT 41.83N 90.56W
08/30/2016 M1.58 INCH CLINTON IA COCORAHS
24-HR TOTAL.
0700 AM HEAVY RAIN 9 SSW MILAN 41.32N 90.63W
08/30/2016 M1.53 INCH MERCER IL COCORAHS
24-HR TOTAL.
0700 AM HEAVY RAIN 1 WNW MOLINE 41.49N 90.51W
08/30/2016 M1.42 INCH ROCK ISLAND IL COCORAHS
24-HR TOTAL.
0730 AM HEAVY RAIN 5 NE OSBORN 41.56N 90.19W
08/30/2016 M1.50 INCH ROCK ISLAND IL MESONET
SINCE MIDNIGHT...DCP JOSI2.
&&
GROSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
842 AM CDT TUE AUG 30 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0337 PM TSTM WND DMG 4 S DEWITT 41.76N 90.55W
08/29/2016 SCOTT IA CO-OP OBSERVER
HEALTHY TREE FELL DOWN AT RESIDENCE...TIME ESTIMATED FROM
RADAR.
&&
GROSSThe Quad Cities radar (KDVN), 40 km away, was scanning. The volume nearest the first event began at 14:01 UTC.
1 flash flood. Local standard time, as filed.
A County Official reported that significant flash flooding was occurring in parts of Geneseo The water was in excess of 6 inches deep. The water levels had returned to normal by 1 PM.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2016Every state in 2016This day in weather historyWarnings in Illinois, August 2016
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: 658064.