An unseasonably strong storm system lifted northward from Iowa into Minnesota on August 18th. This caused a warm front to lift northward across eastern Iowa and showers and thunderstorms with torrential rains to develop across northwest Illinois.
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.
An unseasonably strong storm system lifted northward from Iowa into Minnesota on August 18th. This caused a warm front to lift northward across eastern Iowa and showers and thunderstorms with torrential rains to develop across northwest Illinois. Rainfall totals of 2 to 3 inches caused flash flooding in Carroll County, 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 Aug 18, 1:24 PM CST, 3 hours 36 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 224 PM CDT TUE AUG 18 2015 .SYNOPSIS... ISSUED AT 221 PM CDT TUE AUG 18 2015 WARM FRONT WAS LOCATED ACROSS HIGHWAY 30 WITH LOW PRESSURE NEAR SIOUX FALLS SD. WATER VAPOR LOOPS INDICATE A STRONG SHORT WAVE IN EASTERN KS LIFTING NORTHEAST. THIS SHORT WAVE WILL BE THE FEATURE TO BRING STRONG FORCING INTO THE CWA LATER THIS AFTERNOON AND EVENING. WRF-NMM/HRRR INDICATE A LINE OF THUNDERSTORMS COMING INTO OUR FAR WESTERN COUNTIES AROUND 3 OR 4 PM AND THEN SWEEPING ACROSS THE CWA THROUGH THE EARLY EVENING. AHEAD OF THE LINE DEEP LAYER SHEAR BECOMES STRONG BUT SBCAPES ARE PROBLEMATIC DUE TO EXTENSIVE CLOUD COVER. OPERATIONAL MODELS INDICATE OUR SOUTHERN CWA WOULD HAVE THE HIGHER CAPE. AS OF NOW THE MAIN THREAT WOULD BE DAMAGING WINDS BUT CAN'T RULE OUT A COUPLE OF BRIEF SPIN-UP TORNADOES ALONG BOWING SEGMENTS. OUT AHEAD OF THE MAIN LINE SCATTERED STORMS SHOULD ALSO DEVELOP. && .SHORT TERM...(THIS EVENING) ISSUED AT 221 PM CDT TUE AUG 18 2015 TONIGHT... STRONG SHORT WAVE IN FAR NW MO WILL SWEEP ACROSS THE DVN CWA THIS EVENING WITH STRONG FORCING...STRONG DEEP LAYER SHEAR AND SBCAPES 2500-3000 J/KG. THE MAIN SEVERE THREAT LATE THIS AFTERNOON INTO THIS EVENING WILL BE DAMAGING WINDS ALONG WITH A FEW TORNADOES POSSIBLE...ESPECIALLY EXTREME EASTERN IOWA AND INTO OUR IL COUNTIES. TORRENTIAL RAIN WILL ALSO ACCOMPANY THE STRONGER STORMS. STRONG CYCLONE (FOR MID AUGUST) WILL TRACK INTO NW WI BY MORNING WITH A COLD FRONT SWEEPING ACROSS THE CWA AFTER MIDNIGHT. WILL HAVE THE HIGHEST POPS THIS EVENING THEN DECREASING AFTER MIDNIGHT. BEHIND THE FRONT LOW CLOUDS AND DRIER AIR WILL BE USHERED INTO THE CWA ON INCREASING WEST WINDS. MINIMUM TEMPERATURES WILL RANGE FROM THE UPPER 50S WEST TO THE MID 60S IN THE EXTREME EAST. HAASE .LONG TERM...(WEDNESDAY THROUGH TUESDAY) ISSUED AT 221 PM CDT TUE AUG 18 2015 EARLY FALL WEATHER WILL ARRIVE FOR WEDNESDAY...WITH PASSING CLOUDS AND POSSIBLY A SPRINKLE NORTH. THE COOL NORTHWEST WINDS WILL BE STRONG AT TIMES...AROUND 15 TO 25 MPH...GUSTING TO 30. IN ALL...IT SHOULD BE A VERY PLEASANT DAY FOR THOSE LOOKING FOR A RESPITE FROM SUMMER HUMIDITY. COOL WEATHER WILL LAST THROUGH THURSDAY NIGHT...WITH LOWS IN THE MID 50S IN MOST LOCATIONS WED NIGHT AND THURSDAY NIGHT. DESPITE HAVING A DEEP UPPER LOW TODAY THROUGH THURSDAY IN THE UPPER MIDWEST...THE UPPER FLOW IS EXPECTED TO BE PROGRESSIVE IN NATURE. IN FACT BY FRIDAY...ANOTHER DEEP UPPER TROF WILL DROP INTO THE ROCKIES...WILL FALLING SURFACE PRESSURES IN THE PLAINS. THIS IS EXPECTED TO BRING SEASONALLY STRONG DYNAMICS TO A COLD FROPA AROUND SATURDAY. THAT FRONT WILL LIKELY NOT HAVE MORE THAN 12 HOURS OF RAIN THREAT WITH IT...BUT WITH A MODEL SPREAD ON TIMING OUT ON DAY 5 ON A TYPICAL LEVEL A BROAD PERIOD OF POPS REMAINS FORECAST. FOLLOWING THIS COLD FROPA...ANOTHER HIGH PRESSURE WILL SWEEP OVER THE REGION WITH A QUICK SHOT OF SEASONALLY COOL DRY AIR. ERVIN && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1055 AM CDT TUE AUG 18 2015 EXPECT INCREASING TSTM CHANCES FROM WEST TO EAST FROM LATE MORNING THROUGH THE AFTERNOON...WITH IFR TO MVFR CEILINGS AND VSBYS. HAVE TIMED END OF RAIN FROM 02Z-04Z TONIGHT WITH LINGERING MVFR CONDITIONS OVERNIGHT INTO WEDNESDAY WITH THE POTENTIAL FOR IFR CEILINGS. SOUTHEAST TO SOUTH WINDS AROUND 10 KNOTS THIS AFTERNOON THEN SOUTHWEST TO WEST 10 TO 20 KNOTS TONIGHT INTO WEDNESDAY. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...ERVIN/HAASE SHORT TERM...HAASE LONG TERM...ERVIN AVIATION...HAASE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 504 AM CDT TUE AUG 18 2015 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-191015- 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- 504 AM CDT TUE AUG 18 2015 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 EXPECT PERIODS OF THUNDERSTORMS TODAY AND TONIGHT. A FEW SEVERE STORMS ARE POSSIBLE MAINLY DURING THE AFTERNOON AND EVENING HOURS...WITH DAMAGING WINDS THE MAIN THREAT. AN ISOLATED TORNADO IS ALSO POSSIBLE. POCKETS OF HEAVY RAINFALL ARE ALSO EXPECTED...WITH ISOLATED FLASH FLOODING NOT OUT OF THE QUESTION...MAINLY IN URBAN AREAS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THUNDERSTORMS WILL BE POSSIBLE LATE SATURDAY THROUGH SUNDAY. IT IS TOO EARLY TO DETERMINE THE RISK FOR SEVERE WEATHER. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING ACROSS PORTIONS OF THE OUTLOOK AREA...ESPECIALLY SOUTH AND WEST OF A VINTON- QUAD CITIES-MACOMB LINE. RP KINNEY/12
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
446 PM CDT TUE AUG 18 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0444 PM HEAVY RAIN 1 NNW MAQUOKETA 42.07N 90.67W
08/18/2015 E0.00 INCH JACKSON IA TRAINED SPOTTER
3 TO 4 INCHES OF STANDING AND RUNNING WATER ON ROADS AND
DITCHES FULL IN TOWN.
&&
DLSSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE QUAD CITIES IA IL 453 PM CDT TUE AUG 18 2015 ILC187-182230- WARREN- 453 PM CDT TUE AUG 18 2015 ...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WARREN COUNTY... AT 452 PM CDT...A LINE OF STRONG THUNDERSTORMS WAS ALONG A LINE EXTENDING FROM 6 MILES SOUTHWEST OF NORTH HENDERSON TO 6 MILES SOUTHEAST OF MONMOUTH TO NEAR ABINGDON...AND MOVING EAST AT 40 MPH. WINDS IN EXCESS OF 40 MPH ARE POSSIBLE WITH THESE STORMS. LOCATIONS IMPACTED INCLUDE... COLDBROOK...BERWICK...CAMERON AND GERLAW. A TORNADO WATCH REMAINS IN EFFECT UNTIL 1000 PM CDT FOR WEST CENTRAL ILLINOIS. LAT...LON 4082 9060 4106 9060 4105 9044 4075 9045 TIME...MOT...LOC 2152Z 261DEG 43KT 4102 9054 4085 9055 4078 9046 08
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
519 PM CDT TUE AUG 18 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0515 PM HEAVY RAIN 1 NW DUBUQUE 42.51N 90.70W
08/18/2015 M1.80 INCH DUBUQUE IA TRAINED SPOTTER
90 MINUTE RAINFALL TOTAL.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
526 PM CDT TUE AUG 18 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0455 PM HEAVY RAIN 5 NE MUSCATINE 41.47N 91.00W
08/18/2015 M1.80 INCH MUSCATINE IA TRAINED SPOTTER
RAIN FELL IN PAST 20 MINUTES.
&&
GROSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
545 PM CDT TUE AUG 18 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0545 PM HEAVY RAIN 1 E PRINCETON 41.67N 90.34W
08/18/2015 M1.65 INCH SCOTT IA TRAINED SPOTTER
&&
ERVINPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
547 PM CDT TUE AUG 18 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0545 PM HEAVY RAIN 2 SSW CALAMUS 41.80N 90.77W
08/18/2015 M2.50 INCH CLINTON IA TRAINED SPOTTER
&&The Quad Cities radar (KDVN), 64 km away, was scanning. The volume nearest the first event began at 23:01 UTC.
1 flash flood. Local standard time, as filed.
Law enforcement reported a road was washed out due to flash flooding southeast of Savanna. The time of the event was estimated from radar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2015Every state in 2015This day in weather historyWarnings in Illinois, August 2015
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: 598600.