A cold front moved into Iowa during the evening of the 19th. The severe weather potential was fairly weak given the parameters.
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 cold front moved into Iowa during the evening of the 19th. The severe weather potential was fairly weak given the parameters. CAPE was only around 1000 to 1500 J/kg and precipitable water values were around an inch. The airmass was relatively dry with plenty of dry air in the low levels. Downdraft CAPE was around 1000 J/kg in western Iowa. A line of thunderstorms formed along the cold front during the afternoon and moved into western Iowa during the evening. The storms moved into the far western part of the Des Moines CWA and produced winds of 60 to 70 MPH. Reports of tree and power line damage occurred with some outbuilding damage in Crawford, Carroll, and Sac Counties.
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 19, 6:15 PM CST, 1 hour 21 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 715 PM CDT SAT MAY 19 2012 .SHORT TERM /TONIGHT/... SHORT WAVE OVER WESTERN KANSAS WITH UPPER PV ANOMALY OVER CENTRAL COLORADO WILL LIFT NORTHEAST AND THROUGH NORTHWEST IOWA TONIGHT. COLD FRONT OVER FAR NORTHWEST IOWA LATE THIS AFTERNOON WILL MOVE SLOWLY SOUTHEAST OVERNIGHT AS THE MAIN UPPER LEVEL FEATURES LIFT PARALLEL TO THE SYSTEM. THE BOUNDARY WILL BE NEAR THE INTERSTATE 35 CORRIDOR BY 12Z SUNDAY MORNING. SCT THUNDERSTORMS ONGOING IN ADVANCE OF UPPER LEVEL FEATURES OVER SW NEBRASKA AND CENTRAL KANSAS. THIS AREA SHOULD EXPAND THIS AFTERNOON WITH SFC INHIBITION ERODING INTO EASTERN NEBRASKA ALONG THE MLCAPE AXIS OF 1500+J/KG. OVERALL FOR TONIGHT EXPECT TWO AREAS OF THUNDERSTORMS. A MORE EXPANSIVE AREA MOVING ACROSS NORTHWEST IOWA ASSOCIATED WITH THE UPPER LEVEL FEATURES AND MORE ON THE DEFORMATION SIDE OF THE LOW PRESSURE. STILL WILL BE CONVECTIVE WITH A FEW ISOLATED SEVERE HAIL STORMS POSSIBLE. A LINE OF STORMS POSSIBLE SOUTH OF THE SFC LOW WHICH WILL BE MOVING FROM NEAR OMAHA TO FORT DODGE OVER NIGHT. A FEW BOWING SEGMENTS AND LARGE HAIL STORMS POSSIBLE ALONG THIS REGION. TORNADIC POTENTIAL LOOKS LOW WITH HIGH LCL HEIGHTS AND RELATIVELY MINIMAL LOW LEVEL SHEAR VALUES. .LONG TERM /SUNDAY THROUGH SATURDAY/... THE COLD FRONT AND ASSOCIATED SHOWERS AND THUNDERSTORMS MOVING INTO OUR AREA TONIGHT...AS DISCUSSED IN THE SHORT TERM SECTION...SHOULD CLEAR OUT PRETTY QUICKLY TO THE EAST ON SUNDAY. IN WAKE OF THIS SYSTEM A SURFACE HIGH WILL MOVE SLOWLY ACROSS THE AREA BENEATH NORTHWESTERLY FLOW ALOFT...RESULTING IN QUIET AND COOLER WEATHER FROM SUNDAY THROUGH MONDAY NIGHT. BY TUESDAY MORNING A 500 MB RIDGE WILL BE BUILDING ACROSS THE CENTRAL U.S. AND OVER IOWA FROM THE WEST. MEANWHILE...A POWERFUL 500 MB TROUGH WILL MOVE FROM THE NORTHEAST PACIFIC OVER THE OREGON/WASHINGTON COAST AND BUTTING UP AGAINST THE AFOREMENTIONED RIDGE. INITIALLY THE BUILDING RIDGE WILL BRING A RETURN OF SOUTHERLY LOW-LEVEL FLOW AND WARMER WEATHER ACROSS IOWA...HOWEVER THE EVOLUTION OF THE NORTHWESTERN U.S. TROUGH IS POSING PROBLEMS FOR PROGNOSTIC MODELS IN THE LONG TERM. THERE IS SIGNIFICANT DISAGREEMENT REGARDING THE LATITUDINAL EXTENT TO WHICH THE TROUGH WILL BE ABLE TO DIG SOUTHEASTWARD INTO THE RIDGE...AS OPPOSED TO BEING FORCED IN A MORE EASTERLY DIRECTION. THIS WILL BE COMPLICATED FURTHER BY SEVERAL SUBSEQUENT VORTICITY MAXIMA MOVING ASHORE THE PACIFIC U.S. COAST DURING THE LATTER HALF OF THE WEEK...CONTINUING TO ATTEMPT TO CARVE OUT A WESTERN TROUGH EVEN AS THE CENTRAL/SOUTHEASTERN U.S. HIGH ATTEMPTS TO REBUILD. THE BATTLE BETWEEN THESE TWO LARGE SCALE SYSTEMS WILL LIKELY SET UP A QUASI-STATIONARY FRONTAL BOUNDARY SOMEWHERE ACROSS THE UPPER MIDWEST...ON THE NORTHWESTERN PERIPHERY OF THE 500 MB HIGH AND AT THE SOUTHEASTERN EXTENT OF THE PROGRESSIVE SHORTWAVES MOVING THROUGH THE BASE OF THE TROUGH TO THE WEST. THE RESULTING BOUNDARY WILL LIKELY PROVIDE A FOCUS FOR SEVERAL ROUNDS OF THUNDERSTORM DEVELOPMENT FROM AROUND TUESDAY NIGHT INTO NEXT WEEKEND. THE ECMWF AND GEM INDICATE THAT THE EASTERN PART OF THE TROUGH WILL NOT BE ABLE TO MAKE MUCH SOUTHWARD PROGRESS IN OUR AREA...RESULTING IN THE BOUNDARY MAINLY BEING NORTHWEST OF US FOR MOST OF THE WEEK...WHEREAS THE OPERATIONAL GFS...BUT NOT MOST OF ITS ENSEMBLE MEMBERS...IS MUCH FURTHER SOUTH WITH THE BOUNDARY AND BRINGS MULTIPLE ROUNDS OF PRECIP ACROSS OUR CWA. THIS APPARENT OUTLIER HAD A SIGNIFICANT EFFECT ON THE ALLBLEND POPULATION...CAUSING A PERCEIVED WET BIAS IN THE INITIAL LONG TERM FORECAST. ATTEMPTED TO MITIGATE THIS EFFECT BY OPTING TO GO WITH A DRY FORECAST ON WEDNESDAY AND FROM FRIDAY ONWARD...AND FOCUS FORECAST POPS FROM WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WHEN THE MAXIMUM SOUTHWARD EXTENT OF THE 500 MB TROUGH AND ITS VORTICITY MAXIMA APPEARS MOST LIKELY. ALONG THE SAME LINES INCREASED FORECAST TEMPERATURES FOR FRIDAY AND SATURDAY WHEN STRONGER RIDGING SEEMS MORE LIKELY AS OPPOSED TO THE CLOUDY AND WET WEATHER PREDICTED BY THE OPERATIONAL GFS. UNFORTUNATELY UNCERTAINTY IS HIGH IN THIS SCENARIO AND IT WILL HAVE SIGNIFICANT IMPACTS NOT ONLY ON THE PRECIP FORECAST BUT ALSO THOSE FOR TEMPERATURE...CLOUD COVER...AND WINDS AS WELL. THIS WILL CONSUME MUCH OF OUR FORECASTING EFFORTS IN THE COMING DAYS. && .AVIATION 20/00Z... AREA OF THUNDERSTORMS PUSHING INTO WESTERN IOWA IS EXPECTED TO CONTINUE TO PUSH NORTHEASTWARD AND MAY IMPACT KFOD IN THE NEXT FEW HOURS. OTHERWISE SOME ACTIVITY COULD MAKE IT INTO KDSM OR KMCW LATER THIS EVENING. THEREFORE HAVE HIGHLIGHTED TIMING WITH A VCSH MENTION. OTHERWISE BEST CHANCES FOR TSRA REMAIN AT KFOD...WITH ACTIVITY EXPECTED TO DIMINISH TOWARD THE LATE NIGHT HOURS AT THE OTHER TAF LOCATIONS. COLD FRONT TO PUSH THROUGH THE CWA SUNDAY MORNING WITH WINDS TO SHIFT AROUND TO THE NORTHWEST AND MVFR CIGS EXPECTED MUCH OF THE DAY SUNDAY. CIGS COULD GRADUALLY LIFT TO LOW VFR BY SUNDAY AFTERNOON. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...DONAVON LONG TERM...LEE AVIATION...BEERENDS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 356 PM CDT SAT MAY 19 2012 IAZ004>007-015>017-023>026-033>037-044>048-057>060-070>072-081-082- 092-093-202100- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-SAC-CALHOUN-WEBSTER-HAMILTON- HARDIN-CRAWFORD-CARROLL-GREENE-BOONE-STORY-AUDUBON-GUTHRIE-DALLAS- POLK-CASS-ADAIR-MADISON-ADAMS-UNION-TAYLOR-RINGGOLD- 356 PM CDT SAT MAY 19 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA MAINLY WEST OF INTERSTATE 35. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER NEBRASKA THIS AFTERNOON AND EXPAND INTO THE AREA TONIGHT. A SLIGHT RISK FOR SEVERE WEATHER IS POSSIBLE WITH THESE STORMS. THE PRIMARY THREATS ARE HALF DOLLAR SIZED HAIL AND DAMAGING WINDS IN EXCESS OF 60S MPH. AN ISOLATED TORNADO MAY OCCUR. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SCATTERED NON SEVERE THUNDERSTORMS WILL END SUNDAY MORNING. A FEW PERIODS OF THUNDERSTORMS ARE EXPECTED FROM LATE WEDNESDAY THROUGH THURSDAY. SOME SEVERE STORMS ARE POSSIBLE DURING THIS PERIOD AS WELL. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED FROM 6 PM TO MIDNIGHT. IAZ027-028-038-039-049-050-061-062-073>075-083>086-094>097-202100- BUTLER-BREMER-GRUNDY-BLACK HAWK-MARSHALL-TAMA-JASPER-POWESHIEK- WARREN-MARION-MAHASKA-CLARKE-LUCAS-MONROE-WAPELLO-DECATUR-WAYNE- APPANOOSE-DAVIS- 356 PM CDT SAT MAY 19 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA MAINLY EAST OF INTERSTATE 35. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS ARE POSSIBLE FROM MID EVENING INTO THE OVERNIGHT. AN ISOLATED SEVERE STORM WITH QUARTER SIZED HAIL AND 60 MPH WINDS IS POSSIBLE. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SCATTERED NON SEVERE THUNDERSTORMS WILL END SUNDAY MORNING. A FEW PERIODS OF THUNDERSTORMS ARE EXPECTED FROM LATE WEDNESDAY THROUGH THURSDAY. SOME SEVERE STORMS ARE POSSIBLE DURING THIS PERIOD AS WELL. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION POTENTIAL IS LOW TONIGHT.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 812 PM CDT SAT MAY 19 2012 IAZ044-045-057-070-200215- CRAWFORD-CARROLL-AUDUBON-CASS- INCLUDING THE CITIES OF...DENISON...CARROLL...AUDUBON...ATLANTIC 812 PM CDT SAT MAY 19 2012 ...LINE OF THUNDERSTORMS HEADED INTO WEST CENTRAL IOWA... A LINE OF THUNDERSTORMS IS MOVING EAST NORTHEAST INTO WEST CENTRAL IOWA FROM EASTERN NEBRASKA. STRONG DAMAGING WINDS HAVE BEEN REPORTED WITH THIS LINE OF THUNDERSTORMS...WITH WINDS GUSTS OF 60 TO 70 MPH REPORTED WITH THE THUNDERSTORMS IN EASTERN NEBRASKA. BE PREPARED FOR THE POSSIBILITY OF STRONG WINDS IN YOUR AREA THROUGH 930 PM...AND STAY TUNED TO YOUR FAVORITE WEATHER SOURCE FOR UPDATES. MJB
The Omaha radar (KOAX), 97 km away, was scanning. The volume nearest the first event began at 01:35 UTC.
8 thunderstorm wind. Local standard time, as filed.
Several trees and an old barn was blown over at the intersection of 140th St. and Q Avenue.
A spotter estimated wind gusts of near 65 MPH with some tree damage.
Wind gusts of around 70 MPH caused tree and power line damage.
Power was reported out in town.
Power was out with branches down in town. A trampoline was wrapped around a tree.
Wind gusts were estimated around 60 MPH.
Several large trees were blown down in a cemetery by estimated winds of 60 MPH.
Spotter estimated wind gusts near 60 MPH for about 5 minutes.
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, May 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: 371552, 371545, 371546, 371548, 371551, 371547, 371550, 371549.