A strong warm front was positioned east to west across northern Missouri during the day on the 15th. A strong surge of moisture pushed over the front.
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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 DMX wrote it up.
A strong warm front was positioned east to west across northern Missouri during the day on the 15th. A strong surge of moisture pushed over the front. Precipitable water values were in the 1.5 to 2 inch range over southern Iowa. Thunderstorms repeatedly formed across southern Iowa and northern Missouri. Widespread rainfall of 2 to 4 inches occurred. Many of these areas had received significant rainfall in the days before, so flash flood guidance was quite low. Flash flooding took place in Taylor County during the afternoon. Numerous roads were flooded and closed by flash flooding.
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 Des Moines, IA wrote its last area forecast discussion before the first event at May 15, 7:55 AM CST, 4 hours 53 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 855 AM CDT FRI MAY 15 2009 .UPDATED FOR THE 12Z AVIATION DISCUSSION... .SHORT TERM.../TODAY/ MOISTURE SURGING NWD WITH DEW POINTS IN THE MID 60S INTO SRN KS NOW. DVLPG WRMFNT WILL MAKE PROGRESS NWD...BUT EXPECT IT TO BE TOUGH WITH THE RAIN COOLED AIR IN THE CONVECTIVE AREA. WRMFNT EXPECTED TO REACH THE SRN IA BORDER AREA BY 00Z. KEPT TEMPS DOWN FOR THE MOST PART OVER THE CNTRL AND NERN ZONES AND WENT A BIT WRMR FARTHER NW WHERE RAFL WILL NOT BE AS CONTINUOUS. CUR FFA LOOKS WELL PLACED AND IS SUPPORTED WELL BY THE GFS FROM 00Z...THE 06Z NAM12 AND THE FIM RUNS. NO CHNGS MADE THERE. CONSIDERED PUTTING IN SVR WORDING...HWVR WITH LTL CHC FOR DECENT DESTABILIZATION FEEL THE THREAT IS RELATIVELY LOW AND SHUD BE TO THE SE OF THE CWA FOR THE MOST PART. .LONG TERM.../TONIGHT THROUGH THU/ THE COLD FRONT WILL HEAD SOUTHEAST TONIGHT WITH SOME LINGERING RAIN LIKELY SOUTHEAST DURING THE EARLY EVENING. A MUCH COOLER AIR MASS WILL FILTER INTO THE REGION BEHIND THE FRONT...AND HIGHS SATURDAY ARE ONLY EXPECTED TO REACH THE UPPER 50S TO LOWER 60S. BY SATURDAY NIGHT...THE SFC RIDGE SHOULD STRADDLE THE FORECAST AREA WITH LIGHT WINDS AND IDEAL CONDITIONS FOR RADIATIONAL COOLING. HAVE BUMPED TEMPS DOWN A BIT SOME LOCATIONS AND EXPANDED THE FROST AREA. EXPECTING MODERATING TEMPS INTO THE 70S BY MONDAY AS UPPER RIDGING BUILDS IN. IN THE LATER PERIODS...WILL FAVOR HPC IDEA OF LEANING TOWARDS GFS/GFSENS/UKMET/GEM AND DISCOUNTING THE 15/00Z ECMWF. THE LATEST RUN DIGS A H5 TROUGH INTO THE REGION LATE TUESDAY INTO WEDNESDAY...WHILE THE OTHER MODELS MAINTAIN RIDGING OR ZONAL FLOW AND WARMER TEMPERATURES. ON TUESDAY...THERE MAY BE SOME SHOWERS AND STORMS OVER PARTS OF THE FORECAST AREA DEPENDING ON WHERE THE MAIN SYNOPTIC BOUNDARY SETS UP BEFORE LIFTING NORTH. COLD FRONTAL PASSAGE WILL LIKELY OCCUR LATE WEDNESDAY INTO THURSDAY WITH THE HIGHEST COVERAGE OF PRECIP LIKELY. WILL TEMPER MAX TEMPS FOR TUESDAY A BIT WITH THE BOUNDARY EXPECTED ACROSS THE STATE...OTHERWISE WARMER READINGS LOOK REASONABLE THROUGH THE EXTENDED PERIOD. && .AVIATION...15/12Z SOME UNCERTAINTY IN THE SCENARIO TO UNFOLD TODAY...AS SITUATION SIMILAR TO TWO DAYS AGO...WITH LOW LEVEL STRATUS/MORNING CONVECTION IN PLACE AND AN ADDITIONAL THUNDER THREAT THIS AFTERNOON. MAIN AVIATION SITES IMPACTED TODAY TO BE KDSM AND KOTM...WITH SOME SHOWER/POSSIBLE THUNDER MAYBE SPREADING FAR ENOUGH NORTH TO IMPACT KFOD...KMCW...AND KALO. OTHERWISE CIGS MAINLY IN THE IFR/LIFR RANGE ACROSS SOUTHERN IOWA WITH A FEW HOLES LIFTING THEM INTO MVFR RANGE. CIGS TO REMAIN LOW THROUGHOUT THE MORNING AT LEAST...WHERE ANTICIPATE COULD LIFT THIS AFTERNOON INTO THE MVFR RANGE. SOUTHEASTERLY WINDS AHEAD OF THE SFC LOW OFF TO THE WEST...TO CHANGE TO THE NORTHWEST THIS EVENING INTO THE OVERNIGHT AS THE COLD FRONTAL BOUNDARY MOVES THROUGH. CONTINUED CHANCES FOR -SHRA/-TSRA ACROSS THE SOUTHERN CWA WITH CONVECTION STRETCHING BACK INTO CENTRAL KANSAS ALL MOVING TO THE NORTHEAST. HARD TO NAIL DOWN THUNDER TIMING ATTM...WITH RESPECT TO THE UNCERTAINTY OF ADDITIONAL DEVELOPMENT THIS AFTERNOON. && .DMX WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH TODAY /12Z-00Z/ PORTIONS OF SOUTH CENTRAL AND SOUTHEAST. && LONG TERM...KINNEY SHORT TERM...MS MAY 09 AVIATION...ALBRECHT
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 1103 AM CDT FRI MAY 15 2009 IAZ061-062-073>075-081>086-092>097-161015- JASPER-POWESHIEK-WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS- MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS- 1103 AM CDT FRI MAY 15 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT PERIODS OF THUNDERSTORMS WITH HEAVY RAIN WILL CONTINUE TODAY...BEFORE PUSHING SOUTHEAST OF THE AREA DURING THE EARLY EVENING. ISOLATED SEVERE THUNDERSTORMS WITH QUARTER SIZE HAIL AND 60 MPH WINDS ARE POSSIBLE...MAINLY SOUTH OF HIGHWAY 34. EXPECT LOCALLY HEAVY RAIN...WITH TOTAL RAINFALL OF 3 TO 5 INCHES...AND ISOLATED HIGHER AMOUNTS. A FLASH FLOOD WATCH IS IN EFFECT FOR PORTIONS OF THE AREA. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY ISOLATED THUNDERSTORMS ARE POSSIBLE TUESDAY THROUGH THURSDAY OF NEXT WEEK. THE THREAT FOR SEVERE WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TODAY...ESPECIALLY DURING THE AFTERNOON AND EARLY EVENING HOURS. IAZ004>007-015>017-023>028-033>039-044>050-057>060-070>072-161015- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN- WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE- BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-CASS-ADAIR- MADISON- 1103 AM CDT FRI MAY 15 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT EXPECT SCATTERED NON-SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY EVENING. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY FROST IS EXPECTED EARLY SUNDAY MORNING...MAINLY ALONG AND NORTH OF HIGHWAY 30...AND IN THE NISHNABOTNA RIVER VALLEY. ISOLATED THUNDERSTORMS ARE POSSIBLE TUESDAY THROUGH THURSDAY OF NEXT WEEK. THE THREAT FOR SEVERE WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME. MJA
The Des Moines radar (KDMX), 151 km away, was scanning. The volume nearest the first event began at 18:47 UTC.
3 flash flood. Local standard time, as filed.
Road was closed due to high water on 317th St between Orange Ave and Montana Ave.
Road was closed by high water on 310th St between Orange Ave and Montana Ave.
Road was closed due to high water on 290th St. west of Blockton.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2009Every state in 2009This day in weather historyWarnings in Iowa, May 2009
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: 159137, 159138, 159139.