S. Meanwhile, a cold frontal boundary sank south into northern Iowa during the overnight hours of the 4th into early on the 5th.
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 DMX wrote it up.
A large upper level high pressure area was located over the central U.S. Meanwhile, a cold frontal boundary sank south into northern Iowa during the overnight hours of the 4th into early on the 5th. The atmosphere was unstable, but weakly sheared. Thunderstorms formed along the cold front in northern Iowa, and isolated storms formed in central Iowa as a weak upper level shortwave moved through the state. A microburst occurred in Story County. Several trees were snapped with large branches blown down. Corn was flattened in a one mile long path.
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 Jul 5, 4:45 AM CST, 1 hour 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 545 AM CDT THU JUL 5 2012 .UPDATE 05/12Z AVIATION DISCUSSION... .SHORT TERM /TODAY/... MAIN CONCERNS WILL BE THE HOT TEMPS AGAIN TODAY ALONG WITH CHANCES FOR SOME THUNDER THIS MORNING AND AGAIN ACROSS THE NORTH THIS AFTERNOON. MODELS IN GENERAL AGREEMENT WITH FRONT EXPECTED TO DROP TO JUST SOUTH OF THE IAMN BORDER BY LATE AFTERNOON. CURRENT POSITION OF FRONT FROM NEAR KFSD TO CENTRAL MN BUT BEGINNING TO MOVE SOUTH SLOWLY. TEMPS DROPPING SLOWLY OVERNIGHT WHICH IS PRETTY MUCH EXPECTED...AND DO EXPECT ANOTHER RATHER UNCOMFORTABLE DAY THURSDAY. SOME RESERVATIONS ABOUT HOW HIGH TEMPS WILL GET WITH CLOUDS AND CURRENT DEVELOPING ISOLATED THUNDERSTORMS OVER IOWA FROM THE THUNDERSTORM COMPLEX OVER NEBRASKA. CLOUDS AND WEAK WAVE FROM THE NEBRASKA COMPLEX BEING PUSHED EAST WITH THE H700 AND H500 FLOW. IT IS LIKELY THAT CLOUD COVER WILL DIMINISH SOMEWHAT THROUGH THE DAY...BUT STILL EXPECT THAT SOME FILTERED SUN MAY BE THE CASE ACROSS THE NORTH WITH MAINLY SUNNY SKIES IN THE SOUTH. HEADLINES WILL REMAIN THE SAME...BUT TEMPS/HEAT INDEX MAY NOT REACH AS HIGH ACROSS THE NORTH AS EARLIER FORECAST AND SOME ADJUSTMENTS IN HEADLINES MIGHT NEED TO BE MADE LATER THIS MORNING OVER THE NORTH. STILL THE PERSISTENT HEAT WARRANTS THE CONTINUATION OF THE WARNING OVER MOST OF THE AREA. WITH THE BOUNDARY DRAPED ACROSS THE NORTH...DEW POINTS WILL BEGIN TO POOL ALONG THE FRONT. HAVE RAISED THE DEW POINTS OVER NORTHERN IOWA TO THE MID 70S BY MID TO LATE AFTERNOON. THIS WILL PROBABLY MAKE UP FOR ANY DROP IN TEMPERATURE DUE TO ANY CLOUD COVER TODAY. SPC DAY1 OUTLOOK INCLUDES A SLIGHT RISK OF SEVERE WEATHER TO ABOUT HIGHWAY 20. HOWEVER LITTLE IN THE WAY OF BULK SHEAR EXISTS ALONG OR SOUTH OF THE SINKING BOUNDARY LATER THIS AFTERNOON. WITH THAT SAID...FEEL CHANCES FOR SEVERE WEATHER SHOULD REMAIN MAINLY NORTH OF THE BORDER THOUGH SOME STORMS MAY DEVELOP INTO NORTHERN IOWA BY MID TO LATE AFTERNOON WHERE INSTABILITY IS MAXIMIZED ALONG THE BOUNDARY. MAIN THREAT WOULD BE WIND WITH A SMALLER THREAT FOR HAIL DUE TO THE HIGH FREEZING LEVELS AND WARM CLOUD DEPTHS...UNLESS STORMS BECOME MORE ORGANIZED. H850 MOISTURE REMAINS QUITE HIGH OVER NORTHWEST IOWA AND SOUTHERN MN WITH DEW POINTS 15 TO 17C. STORMS THAT DO DEVELOP HAVE THE POTENTIAL FOR SOME HEAVY DOWNPOURS...BUT HYDRO CONCERNS REMAIN SOMEWHAT LIMITED WITH CURRENT RAINFALL DEFICIT. .LONG TERM /TONIGHT THROUGH WEDNESDAY/... RIDGE WILL REMAIN MAIN CONCERN FOR BEGINNING OF EXTENDED. HAVE LEFT PRECIPITATION CHANCES ACROSS THE NORTH FOR TONIGHT. NAM CURRENTLY THE MODEL WITH THE BEST HANDLE ON ONGOING PRECIPITATION AND HINTS AT A SUBTLE LINGERING BOUNDARY ACROSS THE NORTH FOR THE OVERNIGHT HOURS...AND WILL LIKELY BE THE FOCUS FOR SOME PRECIPITATION CHANCES...HOWEVER...BETTER CHANCES APPEAR TO BE FURTHER NORTH INTO MN. RIDGE REMAINS STRONG THROUGH THE END OF THE WEEK...WITH TEMPERATURES VERY WARM UNDER RIDGE. GOOD SOUTHERLY FLOW...AND WAA INCREASES ESPECIALLY ACROSS THE WEST. HAVE KEPT TEMPERATURES NEAR GOING TEMPS...AND HAVE BUMPED UP A BIT. HOWEVER...MODELS ARE HINTING AT DEW POINTS A BIT COOLER...IN THE 60S TO NEAR 70. COULD SEE SOME DECENT DEW POINTS ALONG AND NEAR THE FRONTAL BOUNDARY ACROSS THE NORTH...AND HAVE KEPT DEW POINTS A BIT HIGHER THERE...BUT HAVE GENERALLY TRENDED DEW POINTS DOWN. HOWEVER...HEAT INDEX VALUES WILL BE 100 TO 110 DEGREES ACROSS THE CWA FOR THURSDAY AND FRIDAY BEFORE FRONT PUSHES THROUGH. THEREFORE EXCESSIVE HEAT WARNING REMAINS IN PLACE. PREVIOUSLY MENTIONED FRONTAL BOUNDARY WILL BE TRICKY FOR THE EXTENDED FORECAST...DEPENDING ON LOCATION. CURRENTLY...MODELS KEEP THE BOUNDARY FURTHER NORTH ACROSS THE NORTHERN PLAINS...BUT MORE AGGRESSIVE GFS SOLUTION CONTINUES TO PUSH BOUNDARY SOUTH ACROSS CWA FOR SATURDAY. IF FRONT IS A BIT FURTHER SOUTH NEAR THE MN/IA BOARDER...WILL SEE INCREASED CHANCES FOR PRECIPITATION THROUGH THE END OF THE WORK WEEK...AND COOLER TEMPERATURES NEAR THE FRONT AND WITH CLOUD COVER. HOWEVER...HAVE KEPT FORECAST TRENDING TOWARDS THE ECMWF SOLUTION...WHICH KEEPS FRONTAL PLACEMENT WELL INTO MN THROUGH THE REMAINDER OF THE WEEK. DO NOT HAVE ENOUGH CONFIDENCE TO INCLUDE POP CHANCES UNTIL LATE FRIDAY...AND EVEN THEN MAY BE TOO SOON. BEST CHANCES FOR PRECIPITATION LOOK TO BE SUNDAY WITH OTHER MODELS IN LINE WITH ECMWF SOLUTION TO PULLING FRONT SOUTH SUNDAY. BEHIND BOUNDARY...TEMPERATURES WILL COOL NICELY...WITH HIGHS BACK NEAR NORMAL FOR THE REMAINDER OF THE PERIOD. WITH FRONT CONTINUING TO PUSH SOUTH...WILL KEEP NORTHWESTERLY FLOW OVER CENTRAL IOWA FOR THE REMAINDER OF THE PERIOD. AGAIN...THIS WILL HELP KEEP TEMPERATURES NEAR NORMAL. IN ADDITION...COULD SEE CHANCES FOR PRECIPITATION WITH SHORT WAVES PUSHING THROUGH THE FLOW. HOWEVER...MODELS DO NOT HAVE A GOOD HANDEL ON THESE SYSTEMS...AND TIMING IS INCONSISTENT. HAVE THEREFORE OPTED FOR A DRY REMAINDER OF THE FORECAST...ESPECIALLY WITH LIMITED MOISTURE RETURN IN NW FLOW. && .AVIATION...05/12Z ISO TO SCATTERED CONVECTION WILL PERSIST THROUGH ABOUT 15Z CENTRAL WITH SCATTERED CONVECTION FAR NORTH THROUGH 15Z AND SOME REDEVELOPMENT EXPECTED AFT 20Z AGAIN. CONVECTIVE COMPLEX IN NEBRASKA HAS PRODUCED A MID LEVEL WAVE WHICH INITIATED CONVECTION HERE. CLOUDS HAVE INCREASED AND OVERSPREAD THE REGION...MAINLY VFR CIGS OF BKN110 TO BKN200 FOR THE DAY. A FEW AREAS MAY DROP BELOW 10KFT... MAINLY KMCW BUT VFR CIGS SHOULD REMAIN. DUE TO LIMITED COVERAGE AND UNCERTAINTY...HAVE KEPT THUNDER AT VCTS FOR NOW. BEST CHANCE FOR SOME CAT THUNDER WOULD BE AT KMCW LATER THIS AM OR AFTERNOON. WINDS WILL NOT BE A FACTOR IN FORECAST TODAY...UNLESS SIGNIFICANT OUTFLOW DEVELOPS FROM THUNDER. LATE TONIGHT FRONT LIFTS BACK NORTH AGAIN AND VFR CONDITIONS SHOULD REMAIN. /REV && .DMX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING UNTIL 7 AM CDT SATURDAY FOR ADAIR-ADAMS- APPANOOSE-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL- CASS-CERRO GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-DECATUR-EMMET- FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT- JASPER-KOSSUTH-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-PALO ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR- UNION-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT. && SHORT TERM...REV LONG TERM...AWB AVIATION...REV
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 502 AM CDT THU JUL 5 2012 IAZ047>050-057>062-070>075-081>086-092>097-061100- BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-JASPER- POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION- CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE- DAVIS- 502 AM CDT THU JUL 5 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT FOR THE AREA. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT FOR THE AREA. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. THUNDERSTORM CHANCES RETURN FRIDAY NIGHT THROUGH MONDAY MORNING. A FEW SEVERE STORMS ARE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. IAZ004>007-015>017-023>028-033>039-044>046-061100- 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- 502 AM CDT THU JUL 5 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT FOR THE AREA. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. ISOLATED THUNDERSTORMS ARE POSSIBLE THURSDAY ACROSS THE AREA. A FEW STORMS MAY BE SEVERE THURSDAY AFTERNOON...WITH LARGE HAIL AND HIGH WINDS ARE THE MAIN THREATS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT FOR THE AREA. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. ADDITIONAL THUNDERSTORM CHANCES RETURN FRIDAY NIGHT AND INTO THE WEEKEND. A FEW SEVERE STORMS ARE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THURSDAY AFTERNOON.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 555 AM CDT THU JUL 5 2012 IAZ037-048-049-051300- HARDIN-STORY-MARSHALL- INCLUDING THE CITIES OF...ELDORA...AMES...MARSHALLTOWN 555 AM CDT THU JUL 5 2012 ...EARLY MORNING THUNDERSTORMS WITH BRIEF HEAVY RAINS AND GUSTY WINDS... A SMALL AREA OF THUNDERSTORMS HAS DEVELOPED OVER CENTRAL IOWA AND IS SLOWLY MOVING TO THE EAST AT 10 MPH. THE STORMS WILL BE CAPABLE OF PRODUCING BRIEF HEAVY DOWNPOURS AND WIND GUSTS TO NEAR 40 MPH THIS MORNING. RAINFALL AMOUNTS OF ONE QUARTER TO UP TO ONE INCH OF RAIN ARE POSSIBLE IN SOME OF THE SLOWER MOVING STORMS. PERSONS TRAVELING ALONG INTERSTATE 35 BETWEEN DES MOINES AND AMES THIS MORNING MAY BRIEFLY ENCOUNTER LOWERED VISIBILITY DUE TO THE THUNDERSTORMS. REV
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 629 AM CDT THU JUL 5 2012 IAZ047>049-051330- BOONE-STORY-MARSHALL- INCLUDING THE CITIES OF...BOONE...AMES...MARSHALLTOWN 629 AM CDT THU JUL 5 2012 ...EARLY MORNING THUNDERSTORMS WITH BRIEF HEAVY RAINS AND GUSTY WINDS... A SMALL AREA OF THUNDERSTORMS HAS DEVELOPED OVER CENTRAL IOWA AND IS SLOWLY MOVING TO THE EAST AT 10 MPH. THE STORMS WILL BE CAPABLE OF PRODUCING BRIEF HEAVY DOWNPOURS...SMALL HAIL...AND WIND GUSTS TO NEAR 50 MPH THIS MORNING. RAINFALL AMOUNTS OF ONE QUARTER TO UP TO ONE INCH OF RAIN ARE POSSIBLE IN SOME OF THE SLOWER MOVING STORMS. PERSONS TRAVELING ALONG INTERSTATE 35 BETWEEN DES MOINES AND AMES THIS MORNING MAY BRIEFLY ENCOUNTER LOWERED VISIBILITY DUE TO THE THUNDERSTORMS. SLOW DOWN AND EXERCISE CAUTION IF VISIBILITY SUDDENLY DROPS DUE TO HEAVY RAINFALL. REV
The Des Moines radar (KDMX), 21 km away, was scanning. The volume nearest the first event began at 11:50 UTC.
1 thunderstorm wind. Local standard time, as filed.
Several trees in a small grove were snapped and a number of branches blown down. A field of corn was flattened with the damage extending for about a mile.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2012Every state in 2012This day in weather historyWarnings in Iowa, July 2012
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: 381052.