An unstable airmass was in place over Iowa with afternoon highs in central and southern Iowa in the mid to upper 90s. Dewpoint temperatures were not very high with most areas around 60.
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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.
An unstable airmass was in place over Iowa with afternoon highs in central and southern Iowa in the mid to upper 90s. Dewpoint temperatures were not very high with most areas around 60. There was 1000 to 2000 J/kg of CAPE available, with 1000 to 1500 J/kg of downdraft CAPE. The freezing level was around 14,500 feet, with only 300 J/kg of CAPE in the -10 C to -30 C layer of the atmosphere, so hail was not an issue. Precipitable water values were around 1.6 inches. The atmosphere was weakly sheared with about 20 kts of shear available. A cold front extended from northeast Iowa into the southwest corner of the state. A scattered line of thunderstorms developed along the cold front. Isolated downdrafts caused damage. Many areas received winds of 40 to 50 MPH. Wind caused roof damage at a restaurant in the Lake Panorama area. The same storm also caused tree damage east-southeast of the Perry airport. A large flatbed trailer was blown across the road as well.
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 Sep 10, 2:31 PM CST, 3 hours earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 331 PM CDT TUE SEP 10 2013 .SHORT TERM.../TONIGHT /... ISSUED AT 247 PM CDT TUE SEP 10 2013 COLD FRONT CURRENTLY FROM ABOUT KMCW SWWD TO SOUTH OF STORM LAKE WILL CONTINUE TO SLOWLY SAG SOUTH TONIGHT MAKING IT INTO CENTRAL TO SOUTHERN IOWA. THERE IS A WEAK VORT MAX ROTATING UP OUT OF KS INTO NE WHICH WILL EVENTUALLY MOVE INTO IOWA THIS EVENING. BUILDING CU AND A COUPLE OF THUNDERSTORMS ARE EVIDENT IN THE VICINITY OF THIS FEATURE AND I EXPECT AT LEAST ISOLATED COVERAGE INTO SW IA ALONG/NEAR THE FRONTAL BOUNDARY. BEHIND THE FRONT THERE IS ALSO PRECIP BREAKING OUT BUT IT IS MORE SHOWERY IN NATURE AND IS NOT EXPECTED TO DEVELOP INTO MUCH ALTHOUGH YOU CANNOT RULE OUT AN ISOLATED THUNDERSTORM. WITH THE FRONT MOVING LITTLE AND A COUPLE MORE IMPULSES EXPECTED TO MOVE ACROSS THE AREA I WILL KEEP SLIGHT CHANCE POPS GOING ACROSS CENTRAL/SOUTHERN IOWA TONIGHT. NOT LOOKING FOR MUCH IN THE WAY OF PRECIPITATION THOUGH AND I WOULD NOT BE SURPRISED IF WE SAW LITTLE MORE THAN SPRINKLES OVER MOST AREAS. AS FOR TEMPS...WITH THE EXCEPTION OF THE FAR NORTHWEST AND NORTH CENTRAL...NOT LOOKING FOR A BIG COOL DOWN TONIGHT. TEMPS ACROSS SOUTHERN IOWA WILL STILL BE IN THE UPPER 60S TO AROUND 70 WITH SOME LOWER VALUES IN THE NISH VALLEY. .LONG TERM.../WEDNESDAY THROUGH TUESDAY/... ISSUED AT 247 PM CDT TUE SEP 10 2013 LINGERING SHOWERS AND THUNDER WILL BE THE MAIN CHALLENGE FOR THE NEXT 24 HOURS FOLLOWED BY THE EXTENT OF THE COOLING OVER THE SUBSEQUENT SEVERAL DAYS AS CANADIAN/GREAT LAKES HIGH SETTLES INTO THE AREA BY THURSDAY AND FRIDAY. FIRST WEAKENING FRONT TODAY OVER NORTHERN IOWA WITH WEAK SFC CONVERGENCE EXPECTED TO BUBBLE UP SOME CONVECTION IN THE NEXT 24 HOURS BUT COVERAGE SHOULD REMAIN LIMITED ALONG THE BOUNDARY DUE TO LACK OF SIGNIFICANT MID TO UPPER LEVEL WIND FIELDS. OVERNIGHT TONIGHT THE INSTABILITY WEAKENS SO ANY THUNDER WILL BECOME MORE ISOLATED THROUGH WED MIDDAY WDNESDAY... WHEN THE FRONT MAY LIGHT UP AGAIN OVER THE SOUTH. THE SECONDARY COLD FRONT...OF MORE INTEREST AS THE MAIN CHANGE IN AIRMASS WILL ARRIVE BY WEDNESDAY NIGHT. THIS WILL DROP TEMPERATURES QUITE A BIT FOR THE REMAINDER OF THE WEEK INTO THE WEEKEND. AS A CANADIAN HIGH SETTLES INTO THE GREAT LAKES AT THE SFC A STRENGTHENING TROUGH AT H500 SETS UP OVER THE HUDSON BAY INITIALLY THEN EAST OVER NEW ENGLAND WILL PROVIDE FOR SEVERAL DAYS OF NORTHWEST FLOW ALOFT. THIS WILL RESULT IN A RETURN TO BELOW NORMAL TEMPERATURES FRIDAY AND SATURDAY BEFORE WARM AIR ADVECTION RETURNS. HIGHS WEDNESDAY WILL STILL REACH THE UPPER 80S TO LOWER 90S SOUTH WHILE THE NORTH WILL BE COOLER...WITH HIGHS IN THE MID 80S. AS THE COOLER AIR ADVANCES SOUTH...LOWS WILL FIRST DROP OFF TO THE 50S NORTH TO LOWER 60S SOUTH THURSDAY MORNING AND INTO THE 40S TO LOWER 50S BY FRIDAY AND SATURDAY MORNING. HIGHS WILL FALL TO THE 60S AND 70S BY FRIDAY AND SATURDAY. WITH THE EXPECTED HIGH AND TENDENCY FOR GREAT LAKES HIGHS TO EXIT THE AREA MORE SLOWLY...WILL BE DROPPING MINS A BIT FOR FRIDAY AND SATURDAY MORNING. THE 00Z MODELS HAVE VARYING SOLUTIONS AS TO HOW QUICKLY WARM AIR ADVECTION THUNDER RETURNS TO THE REGION AND ALSO THE COVERAGE. THE 00Z EURO IS MORE BULLISH ON MOISTURE RETURN AND COVERAGE THAN EITHER THE 00Z GEM/GFS SOLUTIONS. SUBJECTIVE H850 ANALYSIS THIS MORNING YIELDS POSSIBLE REASON FOR EUROS OPTIMISM ACROSS THE CENTRAL PLAINS FOR THE WEEKEND. PERSISTENT MONSOONAL MOISTURE PLUME ACROSS THE SOUTHWEST WITH OLD CLOSED H500 WAVE MAY PHASE WITH NORTHERN STREAM FLOW BY FRIDAY. THIS WOULD ALLOW A CONNECTION BETWEEN THE PLUME AND THE CANADIAN TROUGH AMPLIFYING EAST INTO THE GREAT LAKES BY SATURDAY NIGHT AND SUNDAY. IF SO...THIS WOULD PROVIDE FOR A MORE WIDESPREAD COVERAGE OF PRECIPITATION THAN HAS BEEN SEEN FOR A WHILE. WILL CONTINUE TO MONITOR FOR TRENDS BUT FOR NOW IT APPEARS THAT A SLIGHTLY LATER ONSET IS MORE REASONABLE GIVEN THE GREAT LAKES HIGH. STILL SOME QUESTIONS REGARDING THE EVOLUTION OF THE PLAINS LOW BUT THE NEWEST 12Z EURO SHOWS TWO WAVES WITH A POTENTIAL LESSENING OF POP SUNDAY NIGHT AND EARLY MONDAY MORNING PRIOR TO THE NEXT SYSTEM ARRIVING MONDAY EVENING. THE 12Z GEM/GFS TAKE THE LOW A BIT FARTHER SOUTH NOW AS WELL. ALL SOLUTIONS ARE HINTING AT SEVERAL WAVES PASSING ACROSS THE REGION FROM LATE SAT NIGHT THROUGH SUNDAY NIGHT OR MONDAY...THOUGH EACH MODEL HAS A DIFFERING TAKE ON DEPARTURE OF THE SYSTEM. DUE TO SOME UNCERTAINTY IN THE EVOLUTION...ADJUSTMENTS POSSIBLE IN POP COVERAGE DAYS 6/7. LOOKING FURTHER OUT IN TIME...THE LARGE SCALE PATTERN APPEARS TO BE BREAKING DOWN WITH COLD POOL OVER ALASKA SHEDDING SOME ENERGY INTO THE PACNW. THIS WILL TEND TO STRENGTHEN THE WESTERLIES FARTHER SOUTH AS WE APPROACH THE EQUINOX. && .AVIATION...10/18Z ISSUED AT 1210 PM CDT TUE SEP 10 2013 A WEAK FRONTAL BOUNDARY CONTINUES TO SETTLE INTO NW IA AND WILL PUSH THROUGH THE NW THIRD OF IA BY 00Z. WEAK CONVERGENCE ALONG THE FRONTAL BOUNDARY AND A DISTINCT LACK OF MOISTURE AT PRESENT COMBINED WITH WARM TEMPS ALOFT WILL KEEP ANY SHOWERS OR THUNDERSTORMS AT BAY UNTIL AN UPPER LEVEL DISTURBANCE PUSHES INTO IA AND NEARS THE FRONT. ONLY ISOLATED TO SCATTERED COVERAGE IS STILL EXPECTED ALONG/BEHIND THE BOUNDARY BUT EXPECT FOR KALO WHERE A LITTLE BETTER FORCING IS POSSIBLE...THE PROBABILITY OF SEEING STORMS THROUGH 06Z IS FAIRLY LOW. MOISTURE DOES WORK INTO THE AREA WEDNESDAY AND THE FRONT WILL STILL BE IN SOUTHERN IOWA BUT BY THEN THE BEST CHANCES WILL BE EAST OF THE TAF AREAS. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...BOKSA LONG TERM...REV AVIATION...FAB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 410 PM CDT TUE SEP 10 2013 IAZ025>028-033>039-044>050-057>061-070>073-081>083-092-093-112115- WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-WEBSTER-HAMILTON-HARDIN- GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE-BOONE-STORY-MARSHALL-TAMA- AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-CASS-ADAIR-MADISON-WARREN-ADAMS- UNION-CLARKE-TAYLOR-RINGGOLD- 410 PM CDT TUE SEP 10 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...THIS AFTERNOON AND TONIGHT ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE THIS EVENING INTO THE OVERNIGHT HOURS. AN ISOLATED SEVERE STORM IS POSSIBLE THROUGH MIDNIGHT...WITH DAMAGING WIND THE MAIN SEVERE THREAT. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY CHANCES FOR THUNDERSTORMS CONTINUE INTO WEDNESDAY AND WEDNESDAY EVENING MAINLY SOUTH OF HIGHWAY 20. THUNDERSTORMS CHANCES RETURN TO THE FORECAST SATURDAY THROUGH MONDAY. AT THIS TIME THE SEVERE WEATHER THREAT IS UNCERTAIN. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. IAZ062-074-075-084>086-094>097-112115- POWESHIEK-MARION-MAHASKA-LUCAS-MONROE-WAPELLO-DECATUR-WAYNE- APPANOOSE-DAVIS- 410 PM CDT TUE SEP 10 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...THIS AFTERNOON AND TONIGHT ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE THIS EVENING INTO THE OVERNIGHT HOURS. SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY CHANCES FOR THUNDERSTORMS CONTINUE INTO WEDNESDAY AND WEDNESDAY EVENING. AT THIS TIME THE SEVERE WEATHER THREAT IS LOW. THUNDERSTORMS CHANCES RETURN TO THE FORECAST SATURDAY THROUGH MONDAY. AT THIS TIME THE SEVERE WEATHER THREAT IS UNCERTAIN. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. IAZ004>007-015>017-023-024-112115- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT- 410 PM CDT TUE SEP 10 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...THIS AFTERNOON AND TONIGHT AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE THIS EVENING INTO THE OVERNIGHT HOURS. SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THUNDERSTORMS CHANCES RETURN TO THE FORECAST SATURDAY THROUGH MONDAY. AT THIS TIME THE SEVERE WEATHER THREAT IS UNCERTAIN. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. REV
The Des Moines radar (KDMX), 53 km away, was scanning. The volume nearest the first event began at 23:33 UTC.
2 thunderstorm wind. Local standard time, as filed.
Northwest facing sections of the Port Restaurant were damaged. Pieces of roofing and plywood were thrown into the ditch next to the road. Several roof trusses were visible.
Four 4 inch tree limbs were downed in a yard. Lawn furniture and a grill were blown around and destroyed. A large flatbed trailer was blown across the road.
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, September 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: 467840, 467841.