A cold front settled south into the Des Moines CWA during the predawn hours of the 29th. Severe parameters were relatively weak with limited moisture available.
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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 cold front settled south into the Des Moines CWA during the predawn hours of the 29th. Severe parameters were relatively weak with limited moisture available. Precipitable water was around a half inch with surface dewpoints around 50. The elevated CAPE was only around 400 J/kg with 30 to 40 kts of shear. The freezing level was relatively low, around 10,300 feet. Though there was around 1100 J/kg of downdraft CAPE available, a strong inversion was in place due to the hour of the day. Thunderstorms formed shortly before sunrise along the cold front. The storms continued to develop during the morning hours as the front retreated back to the north. They produced significant amounts of hail, mostly over the far northeast and parts of the north central sections of the Des Moines CWA. Hail up to 2 inches in diameter fell near Waterloo in Black Hawk County. Most of the hail was quarter to half dollar size. There were several reports of hail covering the ground, in some places two to three inches deep.
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 Apr 29, 2:37 AM CST, 1 hour 43 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 337 AM CDT MON APR 29 2013 .SHORT TERM.../TODAY /... ISSUED AT 251 AM CDT MON APR 29 2013 FRONTAL BOUNDARY PROGRESSING ACROSS NORTHERN IOWA THIS MORNING WITH SOME SCATTERED CONVECTION IN VICINITY OF THE FRONT. HAVE HAD REPORTS OF PEA TO DIME HAIL WITH THE STRONGER STORMS BUT CAPES GENERALLY INSUFFICIENT TO PRODUCE LARGE HAIL AT THIS POINT. THE BOUNDARY WILL SETTLE INTO CENTRAL IOWA TODAY BEFORE WASHING OUT BY LATE THIS AFTERNOON AS SOUTHERLY FLOW BECOMES REESTABLISHED ACROSS THE STATE. ONGOING CONVECTION IN THE NORTH WILL CONTINUE TO MOVE EASTWARD ACROSS THE NORTH THIS MORNING WITH ANY ADDITIONAL CONVECTION REMAINING ALONG AND NORTH OF INTERSTATE 80 THIS MORNING NEAR FRONTAL BOUNDARY. THERE APPEARS TO BE A LULL THIS AFTERNOON FOR MUCH OF THE FORECAST AREA AS WEAK SUBSIDENCE ARRIVES BEHIND DEPARTING SHORTWAVE. HOWEVER...MODELS DO INDICATE SOME ADDITIONAL DEVELOPMENT TOWARD THE END OF THE PERIOD (00Z) IN SOUTHERN IOWA WHERE 850MB FLOW BECOMES REESTABLISHED WITH INCREASING THETA-E ADVECTION. MODELS ARE QUITE BALLISTIC WITH MUCAPES THIS AFTERNOON WITH BOTH NAM AND GFS APPROACHING 3500 J/KG IN THE SOUTHEAST. HOWEVER...THIS ASSUMES DEWPOINTS CLOSE TO THE MID 60S WHICH ISNT REALISTIC WITH VALUES IN THE MID TO UPPER 50S MUCH MORE LIKELY. STILL SUFFICIENT INSTABILITY WILL BE PRESENT FOR SOME HAIL THREAT LATE IN THE PERIOD INTO TONIGHT. WINDS COULD ALSO BECOME AN ISSUE IF ORGANIZATION IS SUFFICIENT. TEMPERATURES PROBLEMATIC WITH BOUNDARY AND CLOUDS ADDING UNCERTAINTY TO THE FORECAST. STILL A DECENT AMOUNTS OF WARMTH AS 850MB TEMPS COOLED SLIGHTLY FROM SUNDAYS READINGS...HOWEVER PUSH OF COOLER AIR STALLS ACROSS NORTHERN IOWA. HAVE GENERALLY GONE WARMER IN THE SOUTH TODAY AND HAVE CHOSEN HIGH END OF GUIDANCE. FARTHER NORTH...WINDS WILL BE MORE VARIABLE WITH MIXING NOT AS STRONG AND HAVE STAYED A BIT CLOSER TO GUIDANCE. .LONG TERM.../TONIGHT THROUGH SUNDAY/... ISSUED AT 251 AM CDT MON APR 29 2013 LITTLE HAS CHANGED IN OVERALL FORECAST THINKING FROM PREVIOUS SHIFTS. WARM WEATHER WITH SCATTERED THUNDERSTORM CHANCES WILL PREVAIL THROUGH TUESDAY...WITH A BIG WEATHER CHANGE COMING TUESDAY NIGHT AND WEDNESDAY AND MUCH COOLER AND WETTER WEATHER FOR THE REMAINDER OF THE WEEK. CURRENTLY A VIGOROUS 500 MB SHORTWAVE IS MOVING OVER BRITISH COLUMBIA AND WASHINGTON...AND TODAY AND TONIGHT IT WILL CARVE OUT A LARGE CYCLONIC TROUGH OVER WESTERN CANADA AND THE NORTHWESTERN U.S. AS IT MOVES OVER NORTH DAKOTA BY SUNRISE TUESDAY. MEANWHILE A WEAKENING SURFACE FRONT WILL MOVE INTO IOWA FROM THE NORTHWEST TODAY BEFORE FRONTOLYSIS WASHES OUT THE BOUNDARY TONIGHT. THE REMNANT INSTABILITY GRADIENT AND WEAK LOW LEVEL CONVERGENCE WILL SUPPORT A CHANCE FOR THUNDERSTORM DEVELOPMENT MAINLY ACROSS OUR SOUTHERN AND EASTERN ZONES THIS EVENING AND TONIGHT. WHILE INSTABILITY IS SOMEWHAT IN QUESTION THERE DOES APPEAR TO BE SOME SLIGHT THREAT FOR STRONG TO SEVERE STORMS AS DISCUSSED IN SPC PRODUCTS. THE AFOREMENTIONED VIGOROUS 500 MB SHORTWAVE WILL MOVE FROM NORTH DAKOTA UP INTO CANADA ON TUESDAY...PUSHING A STRONG COLD FRONT INTO CENTRAL IOWA BY THE LATE AFTERNOON. THERE IS A FAIR AMOUNT OF UNCERTAINTY AS TO HOW FAR SOUTHWARD THE FRONT WILL BE ABLE TO PENETRATE INITIALLY WITH THE SHORTWAVE DEPARTING RAPIDLY TO THE NORTHEAST...BUT WHEREVER IT RESIDES BY TUESDAY EVENING IT WILL PROVIDE A FOCUS MECHANISM FOR THUNDERSTORM DEVELOPMENT...AND AGAIN THERE IS SOME THREAT FOR SEVERE WEATHER WITH MOST PARAMETERS LOOKING SOMEWHAT BETTER THAN THE DAY BEFORE. CONCURRENTLY ON TUESDAY ANOTHER STRONG 500 MB SHORTWAVE WILL BE ROUNDING THE BASE OF THE TROUGH OVER THE PACIFIC NORTHWEST...AND WILL SUBSEQUENTLY DIG SOUTHWARD RESULTING IN A SLOWING LONGWAVE TROUGH THAT WILL HAVE SIGNIFICANT IMPACTS ON THE REGION FOR THE REMAINDER OF THE WEEK. IOWA WILL REMAIN EAST OF THE LONGWAVE TROUGH AXIS THROUGH THURSDAY...LEADING TO A PROLONGED PERIOD OF SOUTHWESTERLY FLOW AND PRECIPITATION CHANCES NORTHWEST OF THE NEARLY STALLED SURFACE FRONT. DURING THIS TIME FRAME THERE IS AGAIN SOME UNCERTAINTY REGARDING JUST HOW FAR THE TROUGH/FRONT WILL BE ABLE TO ADVANCE...AND WHETHER ESPECIALLY OUR NORTHWESTERN ZONES WILL BREAK OUT OF THE BACK OF THE PRECIPITATION SWATH OR WHETHER THEY WILL REMAIN UNDER IT LIKE THE SOUTHEAST. IN ANY EVENT HAVE CONTINUED THE UPWARD POP TREND AS THE OVERALL SETUP FOR A PROLONGED RAINFALL EVENT IS CONVINCING...AND LIKEWISE HAVE CONTINUED TO TREND DAYTIME TEMPERATURES DOWNWARD FOR THE LATTER HALF OF THE WEEK. BY LATE THURSDAY A 500 MB LOW WILL CLOSE OFF SOMEWHERE NEAR IOWA AND BECOME TRAPPED WITHIN A DEVELOPING BLOCKING PATTERN...REMAINING NEARBY OR OVERHEAD THROUGH AT LEAST SUNDAY AND EXTENDING THE COLD AND GENERALLY WET WEATHER PATTERN THROUGH THE WEEKEND. AS THE LOW BECOMES OCCLUDED AND SITS OVERHEAD THE AVAILABLE ATMOSPHERIC MOISTURE WILL SLOWLY DIMINISH SO RAIN CHANCES WILL BECOME MORE SCATTERED AND INTERMITTENT...HOWEVER AT THIS RANGE THERE IS NO WAY TO PREDICT THE DETAILS OF THIS EVOLUTION SO HAVE LEFT THE POPS BROAD BRUSHED IN THE EXTENDED WITH CONTINUED COOL TEMPERATURES. IN FACT...THE CURRENT FORECAST WOULD MAKE THE FIRST SEVERAL DAYS OF MAY ONE OF THE COOLEST SUCH PERIODS ON RECORD IN THE LAST SEVERAL DECADES. IT IS EVEN POSSIBLE THAT LIGHT SNOW COULD FALL ACROSS THE NORTH ON THURSDAY MORNING AND/OR FRIDAY MORNING...WHICH IF IT OCCURS WOULD BE THE FIRST SNOW IN IOWA IN MAY SINCE 1997. HOWEVER...THINGS WILL NEED TO LINE UP JUST RIGHT FOR THAT TO HAPPEN. ALTHOUGH IT IS IN THE FAR FORECAST PERIODS...IT DOES APPEAR PROBABLE THAT ONCE THE BLOCK BREAKS AND THE LARGE 500 MB GYRE FINALLY MOVES OFF TO THE EAST THERE SHOULD BE A PERIOD OF RIDGING ALLOWING FOR SOME TEMPERATURE REBOUND EARLY NEXT WEEK. && .AVIATION...29/06Z ISSUED AT 1200 AM CDT MON APR 29 2013 IMMEDIATE CONCERN WILL BE EVOLUTION OF WEAK ELEVATED CONVECTION OVER FAR NW IA AND SRN MN. SUFFICIENT LARGER SCALE FORCING EXISTS TO MAINTAIN IT OVER NRN IA INTO THE EARLY MORNING HOURS. HAVE EXPLICITLY MENTIONED IT AT KMCW BUT CONFIDENCE IS NOT GREAT ENOUGH BEYOND VCSH A TIER SOUTH AT KFOD/KALO. OTHER UPSTREAM NE/SD SHOWERS MAY REACH CENTRAL IA MON MORNING. REMNANTS OF FRONT MAY ALSO TRIGGER ADDITIONAL CONVECTION SE LATE IN THE DAY AS SUGGESTED BY SEVERAL MODELS. HOWEVER THESE MODELS ALSO APPEAR TO BE OVER DOING LOW LEVEL MOISTURE SO NOTHING MORE THAN VCSH WORDING FOR KOTM IN LAST 6 HOURS WITH FAIRLY LOW CONFIDENCE. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...COGIL LONG TERM...LEE AVIATION...SMALL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 430 AM CDT MON APR 29 2013 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-301100- 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-JASPER- POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION- CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE- DAVIS- 430 AM CDT MON APR 29 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT NON-SEVERE THUNDERSTORMS ARE LIKELY EARLY THIS MORNING...MAINLY NORTH OF HIGHWAY 20. A FEW OF THESE STORMS MAY PRODUCE SMALL HAIL. ADDITIONAL THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND TONIGHT...MAINLY SOUTH OF A LINE FROM ATLANTIC TO WATERLOO. SOME OF THESE STORMS COULD BE STRONG TO SEVERE...WITH LARGE HAIL AND STRONG WINDS THE PRIMARY THREATS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THUNDERSTORM CHANCES WILL RETURN ON TUESDAY AFTERNOON AND EVENING...AND PERSIST INTO WEDNESDAY ACROSS SOUTHEASTERN IOWA. ON TUESDAY AFTERNOON AND EVENING SOME OF THE STORMS COULD BE STRONG TO SEVERE...WITH LARGE HAIL AND STRONG WINDS THE PRIMARY THREATS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED. LEE
The Des Moines radar (KDMX), 98 km away, was scanning. The volume nearest the first event began at 10:18 UTC.
16 hail. Local standard time, as filed.
Spotter reported hail a little larger than quarters.
An Iowa State Trooper reported quarter size hail on the highway two inches deep.
Dime to nickel size hail covering a two mile stretch of T-19 north of Wellsburg. Hail was 2 inches deep.
Quarter size hail covering the ground.
Hail covering the ground at the intersection of Greenhill Road and Rainbow Drive.|Relayed by KCVM.
One inch wide by one half inch thick hail measured by KWWL.
Quarter size hall covering the ground two the three inches deep at the intersection of Conger St and Highway 63.
Quarter to half dollar size hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2013Every state in 2013This day in weather historyWarnings in Iowa, April 2013
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: 437743, 437744, 437756, 444405, 437745, 437746, 437752, 437750, 437747, 437748, 437749, 437753, 437754, 437755, 437791, 437751.