A strong frontal boundary was stretched across Iowa. At the same time a 35 kt low level jet pushed warm and humid air into the frontal boundary.
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 strong frontal boundary was stretched across Iowa. At the same time a 35 kt low level jet pushed warm and humid air into the frontal boundary. There was a reasonable amount of elevated instability with 1000 to 1500 J/kg available. The atmosphere was strongly sheared with 50 to 80 kts of effective shear available. Though the CAPE in the -10 to -30 C layer of the atmosphere was not all that high, it was in the 200 to 400 J/kg range. Precipitable water values were greater than 2 sigma above normal, in the 1 to 1.25 inch range. A broad southwest flow was present over the region with a closed upper low over the southwest U.S. A short wave lifted northeast and interacted with the frontal boundary during the morning. An MCS formed, producing heavy rainfall and hail of nickle to quarter size in parts of central into northeast Iowa. The largest hail fell near Stratford in Hamilton County. It was half dollar in size. Several areas received 1 to 2 inches of rain in the 24 hour period ending the morning of the 9th. The heaviest was in Webster County near Stratford with 3.73 inches.
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 8, 8:11 PM CST, 2 hours 9 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 911 PM CDT MON APR 8 2013 .UPDATE... ISSUED AT 908 PM CDT MON APR 8 2013 UPDATED FORECAST FOR INCREASING WINDS NORTHWEST AS FRONT HAS SAGGED SOUTH INTO NORTHERN IOWA THIS EVENING. GRADIENT TO INCREASE MOST AREAS NORTHWEST THROUGH MORNING...BUT REMAIN SUB ADVISORY. SHOWERS HAVE BEEN SLOW TO DEVELOP SO FAR BUT FORCING IS INCREASING. BEST LIFT WILL REMAIN WEST INITIALLY BUT AS FRONT NORTH AT SFC AND ALOFT INCREASES TEMP GRADIENT WILL BE LOOKING AT FORCING SUFFICIENT TO ENHANCE SHOWERS AND THUNDER OVER THE NEXT 3 TO 5 HOURS. && .SHORT TERM /TONIGHT/... CLOUDS WILL BE ON THE INCREASE THIS AFTERNOON AND EVENING AS THE FIRST IN A SERIES OF IMPULSES EJECTS FROM A POTENT LONGWAVE TROUGH DIGGING ACROSS SOUTHERN NEVADA. SIGNIFICANT LOW LEVEL MOISTURE POOLING HAS BEEN TAKING PLACE THIS AFTERNOON ACROSS SOUTHERN IOWA SOUTH OF A SYNOPTIC WARM FRONT LOCATED OVER NORTHERN IOWA. SURFACE DEW POINTS SOUTH OF THE BOUNDARY HAVE RISEN ABOUT TEN DEGREES SINCE SUNRISE AND ARE CURRENTLY RUNNING IN THE MID TO UPPER 50S. DEEPER GULF MOISTURE WORKS INTO THE REGION LATER THIS AFTERNOON WITH PWATS REACHING 1 TO 1.5 INCHES BY 06Z...ESPECIALLY ACROSS THE SOUTH. SUBSTANTIAL 305 TO 310K ISENTROPIC UPGLIDE INTO THIS MOISTURE RICH COLUMN WILL LEAD TO WIDESPREAD SHOWERS AND THUNDERSTORMS DEVELOPING AFTER 00Z AND SPREADING FROM SOUTH TO NORTH WITH THE ISENTROPIC FORCING. MLCAPE VALUES OF 600-1000 J/KG THIS EVENING ALONG WITH 0-6 KM SHEAR VALUES OF 40-50 KTS WOULD SUPPORT THE DEVELOPMENT OF STRONG TO MARGINALLY SEVERE ELEVATED STORMS WITH LARGE HAIL THE BIGGEST THREAT. HOWEVER...WITH A VERY MOIST COLUMN AND LOW NORMALIZED CAPE VALUES...HEAVY RAIN LOOKS TO BE THE BIGGEST THREAT WITH THESE STORMS. .LONG TERM /TUESDAY THROUGH MONDAY/... VERY COMPLICATED FORECAST AHEAD WITH CONVECTIVE AND WINTER ISSUES FOR THE NEXT SEVERAL DAYS. EXPECT WARM ADVECTION DRIVEN SHOWERS AND THUNDERSTORMS TO BE ONGOING AT THE BEGINNING OF THE PERIOD WITH TYPICAL DIURNAL DOWNWARD TREND INTO THE AFTERNOON. HOWEVER H85/H7 WARM/THETA-E ADVECTION REMAINS STRONG INTO THE AFTERNOON EVEN AS MID LEVEL FORCING BEGINS TO WANE. WITH SOLID 1-2KM MOISTURE REMAINING STILL EXPECT MEASURABLE LIGHT RAIN OR DRIZZLE TO CONTINUE WITH HIGH POPS DAY LONG. DO NOT EXPECT TOO MUCH IN THE WAY OF STRONG TO SEVERE STORMS. ALTHOUGH MUCAPES WILL BE INTO THE HUNDREDS...EFFECTIVE SHEAR ESTIMATED BY 1-6KM LAYER DECREASES INTO THE DAY AS H85 FLOW VEERS. MLCAPE/CIN PROJECTIONS INDICATE MINIMAL SURFACE POTENTIAL DUE TO INHIBITION BEING TOO HIGH. EXPECT ANOTHER ROUND OF CONVECTION INTO TUE NIGHT WITH PERSISTENT THETA-E ADVECTION AND PASSAGE OF INVERTED TROUGH...WHICH SHOULD BE INTO SOUTHERN IA IN SOME FORM BY 06Z. ENVIRONMENT EARLY TUE AND AGAIN TUE NIGHT LOOKS FAVORABLE FOR MODERATE TO LOCALLY HEAVY RAINS WITH VERY ANOMALOUS PWS AND DEEP WARM CLOUD DEPTHS LEADING TO EFFICIENT RAINFALL. ALTHOUGH ELEVATED INSTABILITY WILL CHANGE LITTLE TUE NIGHT...PROJECTED EFFECTIVE SHEAR INCREASES ONCE AGAIN SO MARGINAL LARGE HAIL MAY DEVELOP ALONG AND JUST TO THE NORTH AND WEST OF THE INVERTED TROUGH. EVENT TOTAL PRECIP AMOUNTS STILL LOOK LIKE A WIDESPREAD ONE TO TWO INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. ENSEMBLE RIVER FORECAST RUNS STILL SUGGEST MAINLY WITHIN BANK RISES OUTSIDE OF POTENTIAL SOME MINOR FLOODING SOUTH AND EAST IF THE HIGH END MATERIALIZES. THIS IS ABOUT THE SAME TYPE PRECIP TYPE STARTS TO BECOME AN ISSUE FAR NW AS COLD AIR GRADUALLY FILTERS SOUTH AND EAST BEHIND DEPARTING SURFACE FEATURES. ALTHOUGH ICE IS INTRODUCED INTO THE COLUMN WED...SURFACE TEMPS LOOK TO STAY TOO WARM FOR ANYTHING OTHER THAN A COLD RAIN. BY WEDNESDAY NIGHT...SOUNDINGS AND PLAN VIEW RH FIELDS STRUGGLE TO FIND MUCH RH COLDER THAN -10C LEADING TO FREEZING RAIN BEING MORE OF A COOL SEASON CONCERN THAN SNOW. BY THU THE POTENTIAL OF ICE ALOFT AND FAVORABLE SURFACE TEMPS MAY COME TOGETHER FOR SOME ACCUMULATIONS NORTH. NO WATCH YET WITH NO GREAT CONFIDENCE IN HOW FORCING AND TEMPS AT THE SURFACE AND ALOFT WILL FAVORABLE PHASE...BUT WILL SURELY ADD MENTION OF SNOW AND FREEZING RAIN ACCUMS TO HAZARDOUS WEATHER OUTLOOK. SYSTEM SHOULD FINALLY EXIT BY THE END OF THE WORK WEEK WITH LINGERING LOW LEVEL CYCLONIC FLOW KEEPING TEMPERATURES COOL AND BELOW NORMAL. POPS WILL RETURN FOR THE WEEKEND HOWEVER AS A LONG WAVE TROUGH RE-DEVELOPS OVER THE ROCKIES LEADING TO LOW PRESSURE MOVING FROM THE PLAINS INTO THE MISSOURI VALLEY. TIMING STILL UP IN THE AIR WITH 12Z GFS FASTER THAN THE 12Z ECMWF SO THE WEEKEND SEEMS MOST FAVORABLE AT THIS POINT. HAVE CARRIED LOW POPS MON BUT PEAK AT 12Z ECMWF IS NOW DRY SO THESE MAY END UP BEING OVERZEALOUS IF THAT TREND CONTINUES. ALTHOUGH IT IS CERTAINLY POSSIBLE...HAVE NOT INCLUDED THUNDER MENTION AS OF YET UNTIL CONFIDENCE INCREASES IN PREFERRED PERIOD INCREASES. && .AVIATION...08/00Z ISSUED AT 615 PM CDT MON APR 8 2013 POOR CONDITIONS EXPECTED AFT 04Z AND MUCH OF PERIOD AS FRONT OVER IA BECOMES RATHER ACTIVE AFTER 03Z. MODELS PROG THUNDERSTORM COMPLEX TO FORM WEST ALONG BOUNDARY AND HEAD EAST INTO IA ALONG WITH CONVECTION BREAKING OUT ALONG UPPER LEVEL BOUNDARY OVER AREA IN NEXT COUPLE OF HOURS. HAVE SPED UP ARRIVAL OF MVFR/IFR CIGS ALONG WITH HITTING TAFS HARDER FOR RA AFTER PRECIPITATION ARRIVES. WINDS NORTH WILL BECOME NE AND GUSTY ESPECIALLY AFT 06Z AS LOW DEEPENS TO OUR WEST. THOUGH COVERAGE OF IFR CIGS/RAIN AND MVFR BR WILL BE WIDESPREAD...THUNDER WILL BE DIMINISHING AFT 03Z AND WILL COVER AREA WITH VCTS RATHER THAN -TSRA UNTIL ORGANIZED CONVECTION ARRIVES. AFT 13Z RA WILL CONTINUE NORTH AND SCT VCTS -RA SOUTH SITES. WILL ADDRESS TIMING AND COVERAGE ISSUE OF LATER PORTION OF TAF WITH 06Z PACKAGE. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && UPDATE...REV SHORT TERM...SKOW LONG TERM...SMALL AVIATION...REV
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 421 PM CDT MON APR 8 2013 IAZ004>007-015>017-023>028-033>039-044-091100- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN- WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD- 421 PM CDT MON APR 8 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN AND CENTRAL IOWA. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP TONIGHT. THOUGH SEVERE WEATHER IS NOT EXPECTED...A FEW STORMS COULD PRODUCE UP TO PENNY SIZE HAIL. SOME OF THE STORMS MAY ALSO PRODUCE LOCALLY HEAVY RAINS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY SEVERAL PERIODS OF THUNDERSTORMS ARE EXPECTED TUESDAY INTO TUESDAY NIGHT. SEVERE WEATHER IS NOT ANTICIPATED...ALTHOUGH A FEW STORMS MAY PRODUCE LOCALLY HEAVY RAINS. THE PROLONGED PRECIPITATION MAY PRODUCE A FEW INCHES OF RAIN IN A FEW LOCATIONS BY WEDNESDAY. ALTHOUGH FLOODING IS NOT ANTICIPATED...CONSIDERABLE PONDING WATER ON ROADS AND IN DITCHES IS QUITE POSSIBLE. BY WEDNESDAY MORNING AND AGAIN WEDNESDAY NIGHT INTO THURSDAY MORNING...ACCUMULATIONS OF SNOW OR FREEZING RAIN MAY OCCUR LEADING TO HAZARDOUS TRAVEL CONDITIONS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED BRIEFLY...BUT OVERALL IS NOT LIKELY. IAZ045>050-057>062-070>075-081>086-092>097-091100- 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- 421 PM CDT MON APR 8 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND SOUTHERN IOWA. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP TONIGHT. THOUGH SEVERE WEATHER IS NOT EXPECTED...AN ISOLATED STORM COULD PRODUCE UP TO PENNY SIZE HAIL. SOME OF THE STORMS MAY ALSO PRODUCE LOCALLY HEAVY RAINS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY PERIODS OF THUNDERSTORMS ARE EXPECTED TUESDAY INTO TUESDAY NIGHT. A FEW STORMS MAY BE STRONG TO SEVERE WITH LARGE HAIL THE PRIMARY THREAT. THE PROLONGED PERIOD OF RAIN MAY PRODUCE SEVERAL INCHES OF RAIN IN A FEW LOCATIONS BY WEDNESDAY. ALTHOUGH FLOODING IS NOT ANTICIPATED...CONSIDERABLE PONDING WATER ON ROADS AND IN DITCHES IS QUITE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED BRIEFLY TUESDAY AND TUESDAY NIGHT. SMALL
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 1101 PM CDT MON APR 8 2013 IAZ082-083-093-094-090500- CLARKE-DECATUR-RINGGOLD-UNION- 1101 PM CDT MON APR 8 2013 ...A STRONG THUNDERSTORM POSSIBLY PRODUCING HAIL... AT 1055 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER EAST CENTRAL RINGGOLD COUNTY...MOVING NORTH AT 25 MPH. PENNY SIZE HAIL...ARE POSSIBLE WITH THIS STORM. LOCATIONS IMPACTED INCLUDE... BEACONSFIELD... TINGLEY... GRAND RIVER... ELLSTON... ARISPE... AFTON... THAYER... OSCEOLA... MURRAY... THIS STORM HAS THE POTENTIAL TO PRODUCE UP TO PENNY SIZED HAIL AND GUSTY WINDS TO 40 MPH. VACHALEK
The Des Moines radar (KDMX), 110 km away, was scanning. The volume nearest the first event began at 04:20 UTC.
14 heavy rain, 6 hail. Local standard time, as filed.
Hail still in ditches the next morning. Siding of houses damaged and plastic on shed damaged with window screens also torn.
Rainfall 1.53 inches.
Rainfall 2.68 inches.
Rainfall 1.02 inches.
Rainfall 1.88 inches.
Rainfall 1.33 inches.
Rainfall 1.54 inches.
Rainfall 1.97 inches.
Hail was up to half dollar size.
Rainfall 1.83 inches.
Rainfall 1.35 inches.
Rainfall 1.26 inches.
Rainfall 2.00 inches.
Relayed by kcrg television.
Rainfall 1.18 inches.
Rainfall 3.73 inches in the past 24 hours.
Rainfall 1.10 inches.
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: 439348, 433380, 433381, 433382, 433383, 433385, 433386, 433387, 433373, 433388, 433389, 433374, 433390, 433391, 433375, 433376, 433378, 433392, 433393, 433394.