82 inches between 0600 and 0745 LST. This combined with moderate rainfall over the Walnut Creek headwaters and wet anticedent conditions resulted in localized flash flooding on Walnut Creek downstream of where Pioneer Creek runs into Walnut Creek.
Every event with a place to put it; 1 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.
Localized heavy rain of 3 plus inches fell in the headwaters of Pioneer Creek southwest of Olin, Iowa with Mechanicsville, Iowa reporting 2.82 inches between 0600 and 0745 LST. This combined with moderate rainfall over the Walnut Creek headwaters and wet anticedent conditions resulted in localized flash flooding on Walnut Creek downstream of where Pioneer Creek runs into Walnut Creek. Two county gravel roads were unindated with high water; 35th street between 160th and 145th Avenues had over a foot of water over it while 42nd Street had 8 to 10 inches of water over it between 160th Avenue and the Olin, Iowa city limits.
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 21, 2:40 AM CST, 5 hours 20 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 340 AM CDT MON JUN 21 2004 .SYNOPSIS... WEAK SURFACE EASTERN NEBRASKA LOW PRODUCING SHOWERS AND THUNDERSTORMS WITH EASTERN EDGE NOW INTO CENTRAL IOWA...MAINLY ALONG A LOBE ON 850MB FRONT AHEAD OF MAIN SHIELD. PRESSURE FALLS SUPPORT UPPER AIR OF THIS PRECIPITATION MOVING ACROSS AREA THIS MORNING. WIDESPREAD CLOUDS TO STAY OVER REGION INTO MID AFTERNOON SUPPORTING LOWER HIGH TEMPS MOST AREAS IN LOW TO MID 70S. WEDGE OF 60-65 DEWPOINTS IN SW IOWA SUPPORTING MODERATE AMOUNTS OF PRECIPITATION DESPITE WEAK FORCING. LIMITED INSTABILITY SUGGEST MARGINAL STORMS WITH MAINLY SHOWERS. ..NICHOLS.. .SHORT TERM...(TODAY AND TONIGHT) MAINLY USE NOWCAST TOOLS TODAY (SEE ABOVE DISCUSSION) FOR CATEGORICAL POPS EXCEPT FAR SOUTH AND NORTH WITH MAINLY ONE QUARTER TO ONE HALF INCH AMOUNTS. 88D DISTANCE TIME TOOL SUPPORT MAIN RAIN SHIELD TO PASS MOST FORECAST AREA BETWEEN 11- 17Z (6-12 AM). ETA REASONABLE FOR SOME WIDELY SCATTERED SHOWERS OR A STRAY STORM ALONG FRONT PASSING NEAR DINNER HOUR WITH SOME DIABATIC HEATING. WITH CLOUDS...MAINLY ON LOW SIDE OF GUIDANCE BLEND WITH POSSIBLE AREAS EAST OF MISSISSIPPI RIVER/HIGHWAY 61 TO BE AS MUCH AS 5 DEGREE BELOW BLEND IF KEEP CLOUDS. CLEARING TO MOVE ACROSS THIS EVENING ON MODERATE NW WINDS SUPPORTING LOWS NEAR BLEND NW AND JUST ABOVE SOUTH WHERE CLOUDS HANG IN LONGER. ..NICHOLS.. && LONGER TERM...(TUESDAY THROUGH SUNDAY) WELL ADVERTISED BROAD CYCLONIC FLOW CONTINUES TO GET IMPLANTED ACRS THE MIDWEST ON TUE... SETTING THE STAGE FOR CONTINUED SEASONABLY COOL WX REGIME WITH OCCASIONAL SPOKES OF ENERGY GETTING FUNNELED THROUGH THIS FLOW FOR REST OF THE WEEK AS WESTERN CONUS BLOCKING PATTERN HOLDS FIRM. SFC RIDGE AXIS WILL LOOK TO PROGRESS ACRS THE CWA ON TUE FOR A PARTLY TO MOSTLY SUNNY/FAIR WX DAY. LOOKING AT EXTENT OF PROGGED GLANCING BLOW OF H85 COLD POOL AND MIXING...ONGOING HIGHS OF LOW TO MID 70S STILL LOOK ON TARGET TAKING INTO ACCOUNT SOME INSOLATION. SHORT RANGE MODELS(ESPECIALLY GFS) SUGGEST INITIAL WEAK WAVE ROTATING DOWN ACRS THE AREA AS EARLY AS TUE NIGHT...BUT BETTER EXTRAPOLATION OF MORE SIGNIFICANT UPPER LEVEL WAVE AND ASSOCIATED SFC REFLECTION LOW/FRONT TO SKIRT ACRS AND JUST TO THE NORTH OF THE AREA WED AFTERNOON. DEEPENING RETURN FLOW IN THE LOW TO MID LEVELS TO INCREASE THERMAL PARAMETERS...INSTABILITY AND THTA-E FEED ACRS THE AREA AHEAD OF CLIPPER TYPE SYSTEM ENOUGH TO POSSIBLY FUEL A FEW SEVERE THUNDERSTORMS(MAINLY HAILERS) WED AFTERNOON. OF MORE INTEREST THOUGH...IS SHORT RANGE MODEL HANDLING OF PIVOTING STRONG WAVE AROUND JAMES BAY REGION VORTEX AND PLUNGING DOWN ACRS THE UPPER MS RVR VALLEY LATER WED NIGHT INTO TUE. BOTH THE ETA AND GFS PROG A UNSEASONABLY STRONG 30+ VALUE VORT MAX TO ROTATE DOWN ACRS MN/WI/ NORTHERN IA AND INDUCING INTENSE CVA/POS OMEGAS JUST TO THE NORTH OF THE CWA WED NIGHT. WILL BE INTERESTING TO SEE HOW FOLLOWING MODEL RUNS HANDLE THIS FEATURE...BUT FOR NOW WILL KEEP PRECIP CHANCES GOING INTO THU WITH SECONDARY BUT POTENTIAL STRONGER SFC WAVE AND FROPA. FOLLOWING REINFORCING COOL SHOT AND RIDGE AXIS TO FOLLOW THU WAVE PASSAGE FOR END OF WEEK...WHICH NOW LOOKS DRY FOR FRI AND SAT. BUT WITH CONTINUING NORTHWEST FLOW PATTERN OVER THE WESTERN GRT LKS... UPPER COOL POOL AND VORT SPOKES...WOULD NOT RULE OUT DIURNAL/ AFTERNOON INSTABILITY SHOWERS FRI OR SAT AFTERNOON...BUT BEST CHANCES SHOULD BE OFF TO THE NORTHEAST OVER WI. ..12.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && NICHOLS/12
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 510 AM CDT MON JUN 21 2004 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-221000- 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- 510 AM CDT MON JUN 21 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 COLD FRONT PUSHING EAST ACROSS THE AREA TODAY WILL PRODUCE SHOWERS AND SOME THUNDERSTORMS...WITH THE BULK OF THE ACTIVITY OCCURRING THROUGH MIDDAY. NO SEVERE STORMS ARE EXPECTED AND IT APPEARS THAT GENERAL RAINFALL AMOUNTS WILL RANGE FROM A QUARTER...TO A HALF INCH OR LESS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY AS ANOTHER FRONTAL SYSTEM SKIRTS ACROSS THE UPPER MIDWEST. EARLY INDICATIONS SUGGEST THERE MAY BE ENOUGH WARMING AND BUILDING INSTABILITY ON WEDNESDAY AHEAD OF THE FRONT...TO ALLOW SOME STORMS TO BECOME STRONG ENOUGH TO PRODUCE HAIL. AN EVEN STRONGER UPPER LEVEL DISTURBANCE WILL LOOK TO ROTATE DOWN ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY FOR A CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS. STAY TUNED FOR LATER FORECASTS AND UPDATES CONCERNING THIS DEVELOPING STORM SYSTEM FOR THE MIDDLE PART OF THE WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME FOR TODAY OR TONIGHT. 12
The Quad Cities radar (KDVN), 73 km away, was scanning. The volume nearest the first event began at 13:59 UTC.
1 flash flood. Local standard time, as filed.
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, June 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: 5416467.