Thunderstorms developed north of a warm front located across Southern Iowa and Central Illinois. Due to a near tropical atmosphere and a decaying low level jet, rainfall amounts were quite copious and occurred over very short time periods.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
Thunderstorms developed north of a warm front located across Southern Iowa and Central Illinois. Due to a near tropical atmosphere and a decaying low level jet, rainfall amounts were quite copious and occurred over very short time periods. The main problems were in urban areas where storm sewers were unable to handle the rate of rainfall.
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 Jul 9, 3:29 AM CST, 2 hours 31 minutes earlier.
AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE QUAD CITIES IA IL 429 AM CDT FRI JUL 9 2004 .SYNOPSIS...STATIONARY FRONT EXTENDS ACROSS NORTHERN MISSOURI THIS MORNING...FROM MKC EAST-SOUTHEAST TO BETWEEN UIN AND STL. STRONG CONVECTIVE COMPLEX IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA...ALONG THE FRONT...IS ASSOCIATED WITH A STRONG VORT MAX. && .SHORT TERM...(TODAY AND TONIGHT) THE PRIMARY FORECAST CONCERN FOR THE FIRST 24 HOURS IS THE MOVEMENT OF THE FRONT TO OUR SOUTH...AND PRECIP ALONG AND NORTH OF FRONT. THE SHORT-TERM MODELS DO A POOR JOB INITIALIZING WITH THE NEBRASKA VORT...WITH THE GFS BEING TOO FAR NORTH AND THE ETA AND NGM TOO FAR WEST. THE RESULT IS SIGNIFICANTLY DIFFERENT PLACEMENT BY 00Z THIS EVENING...WITH THE GFS TAKING THE VORT NORTH OF DBQ...THE NGM WELL SOUTH TO CENTRAL MISSOURI...AND THE ETA STRAIGHT ACROSS THE FA. EXCLUDING THE NGM...WHICH SEEMS VERY UNLIKELY...THE ETA LOOKS BEST. UNLIKE THE LAST RUN...THE FRONT ITSELF STAYS SOUTH THRU THE FIRST 24 HOURS...WITH POSSIBLE BRIEF INCURSIONS INTO THE SOUTHERN PORTION OF THE FA. CONVECTION WILL PROBABLY INCREASE ACROSS THE SOUTH EARLY TODAY...BRIDGING THE GAP BETWEEN THE ACTIVITY IN SOUTH CENTRAL IOWA AND CENTRAL ILLINOIS. THAT SHOULD END MIDMORNING...WITH THE BEST CHANCE OF RENEWED CONVECTION ACROSS THE FA BEING MID AFTERNOON INTO EARLY EVENING...WITH THE VORT ARRIVING...GOOD VVS...AND A LOW-LEVEL JET PRODUCING LOW-LEVEL CONVERGENCE MAINLY CENTRAL OR NORTH. ANOTHER VORT MAX LATE TONIGHT COULD BRING ADDITIONAL CONVECTION...MAINLY AFTER MIDNIGHT. THE PRIMARY LOW-LEVEL JET WILL BE WELL SOUTH OF THE FA...BUT COULD ENHANCE PRECIP CHANCES IN FAR SOUTHERN PORTIONS. SEVERE CHANCES ARE LOW FOR BOTH TODAY AND TONIGHT. LOCALLY VERY HEAVY PRECIP WILL BE POSSIBLE DUE TO PRECIPITABLE WATER NEAR 2 INCHES. ...REA... && .LONG TERM...(SATURDAY THROUGH FRIDAY)...EXPECT FRONT TO STRETCH ALONG HIGHWAY 34 CORRIDOR SATURDAY MORNING...THEN LIFT SLOWLY NORTH DURING THE DAY. WITH PLENTY OF LOW LEVEL MOISTURE POOLING ALONG FRONT WILL KEEP LOW POPS GOING THROUGH DAY. OVERALL...THINK GFS MAY BE OVERDOING SURFACE HIGH TO NORTHEAST EARLY AND WENT CLOSER TO ETA SOLUTION. KEPT IDEA OF THUNDERSTORM CHANCES THROUGH SUNDAY NIGHT AS ANOTHER LOW EMERGES OUT OF ROCKIES AND WE SEE MORE MCS ACTIVITY EACH NIGHT WITH AREA GENERALLY ALONG AND NORTH OF I-80 FAVORED CLOSER TO SURFACE FRONT AND H85 FRONT WELL TO NORTH. FOLLOWED SIMILAR ETA/UKMET SOLUTION WITH SURFACE LOW PATH AND FROPA EARLY MONDAY MORNING. FEW CHANGES BEYOND WITH DRY MONDAY INTO MON NIGHT FOR MOST OF AREA AS HIGH MOVES OVER AREA. BUILDING RIDGE OVER ROCKIES WILL PLACE NORTHEAST HALF OF FORECAST AREA AT EDGE OF ACTIVE NORTHWEST FLOW WITH GULF MOISTURE RETURNING FOR THUNDERSTORM CHANCES LATE TUESDAY THROUGH THURSDAY AND MADE FEW CHANGES TO GOING FORECAST THESE PERIODS. H5 HEIGHTS RISE FRIDAY AS UPPER RIDGE SHIFTS EAST AND WILL INTRODUCE IN FORECAST SUITE AS DRY. ...SHEETS... && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && REA/SHEETS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 532 AM CDT FRI JUL 9 2004 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-101100- BENTON IA-BUCHANAN IA-BUREAU IL-CARROLL IL-CEDAR IA-CLARK MO- CLINTON IA-DELAWARE IA-DES MOINES IA-DUBUQUE IA-HANCOCK IL- HENDERSON IL-HENRY IA-HENRY IL-IOWA IA-JACKSON IA-JEFFERSON IA- JO DAVIESS IL-JOHNSON IA-JONES IA-KEOKUK IA-LEE IA-LINN IA-LOUISA IA- MCDONOUGH IL-MERCER IL-MUSCATINE IA-PUTNAM IL-ROCK ISLAND IL- SCOTLAND MO-SCOTT IA-STEPHENSON IL-VAN BUREN IA-WARREN IL- WASHINGTON IA-WHITESIDE IL- 532 AM CDT FRI JUL 9 2004 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST IOWA... EAST CENTRAL IOWA...SOUTHEAST IOWA...NORTHWEST ILLINOIS...NORTH CENTRAL ILLINOIS...WEST CENTRAL ILLINOIS AND NORTHEAST MISSOURI. .DAY ONE...TODAY AND TONIGHT A STATIONARY FRONT ACROSS THE AREA WILL BE THE FOCUS FOR SCATTERED SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT. AREA WIDE RAINFALL AMOUNTS OF UP TO AN INCH ARE POSSIBLE...WITH LOCALIZED AMOUNTS OF 2 INCHES...MAINLY NEAR AND SOUTH OF INTERSTATE 80. NUISANCE FLOODING ON SMALL STREAMS...AND IN LOW-LYING AREAS...WILL BE POSSIBLE. NO SEVERE THUNDERSTORMS ARE EXPECTED. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY COMPLEX OF THUNDERSTORMS WITH HEAVY RAIN MAY AFFECT THE OUTLOOK AREA SATURDAY MORNING...ESPECIALLY SOUTH OF INTERSTATE 80. ADDITIONAL THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE AFTERNOON AS AS A WARM FRONT LIFTS NORTH. THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE LOCALLY HEAVY RAINFALL WITH A LESSER THREAT OF DAMAGING WIND AND LARGE HAIL. SATURDAY NIGHT...THUNDERSTORMS WITH HEAVY RAIN WILL FOCUS MAINLY NORTH OF HIGHWAY 20. LATE SUNDAY INTO SUNDAY NIGHT...A COLD FRONT MAY BRING ADDITIONAL THUNDERSTORM COMPLEXES THROUGH THE AREA WITH THE POTENTIAL FOR MORE HEAVY RAIN AND POSSIBLY MINOR FLOODING. THUNDERSTORMS WILL BE POSSIBLE AGAIN TOWARD MID WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT. REA/DLS
The national radar mosaic for the moment the first event began.
2 heavy rain. Local standard time, as filed.
2.50 inches in past 2.5 hours; water ponding on a gravel road.
Estimated 1.50 inches in two hours with around an inch of it falling in 40 minutes with considerable street flooding. Construction at one of the high schools blocked the storm sewer which caused water to flow into the first floor. However, no damage occurred.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2004Every state in 2004This day in weather historyWarnings in Iowa, July 2004
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: 5418324, 5418325.