A very hot airmass was in place across Iowa ahead of a weak cold front. Warm air from the Rockies pushed the 850 mb air to between 24 and 26 C.
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The episode as NWS DMX wrote it up.
A very hot airmass was in place across Iowa ahead of a weak cold front. Warm air from the Rockies pushed the 850 mb air to between 24 and 26 C. Surface temperatures soared into the 95 to 105 F range with dewpoints in the mid 40s across northwest Iowa, rising to around 60 over the southeast. The freezing level was quite high at 14,000 feet. CAPE was limited with the scant moisture present and a strong enhanced mixed layer was over the state. By the late afternoon downdraft CAPE rose to 1500 to 1700 J/kg and the inversion that was present had eroded away. Weak shear was present in the atmosphere with less than 25 kts of effective shear available. The cold front dropped southeast into the state during the afternoon and a scattered line of thunderstorms developed along the front from north central into west central Iowa. A few of the storms produced high winds of 65 MPH or more causing considerable blowing dust and some roof and shingle damage.
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 14, 2:33 PM CST, 1 hour 10 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 333 PM CDT TUE MAY 14 2013 .SHORT TERM.../TONIGHT/... I ISSUED AT 306 PM CDT TUE MAY 14 2013 AFTER RECORD HEAT AND CENTURY MARK TEMPS TODAY WILL BE LOOKING AT COOL FRONT DRIFTING SOUTHEAST THIS EVENING AND OVERNIGHT. CONVECTIVE ELEMENTS TRYING TO GET GOING ALONG THE BOUNDARY AND CONVERGENCE ZONE OVER NORTHWEST IA AND NORTHEAST NEBRASKA...BUT HAVING DIFFICULTY WITH CAP AND LACK OF REAL FORCING. TREND SHOULD CONTINUE WITH PERHAPS AN ISOLATED SHOWER OR THUNDERSTORM THIS EVENING IN THE VICINITY OF THE BOUNDARY. AFTER SUNSET THERE IS A POTENTIAL FOR SOME CONVERGENCE ALOFT AS H850 FLOW INCREASES NEAR AND JUST SOUTH OF THE BOUNDARY OVERNIGHT. AGAIN...WITH NEARLY PARALLEL FLOW THE CHANCES REMAIN SLIM THAT MUCH REALLY GETS ORGANIZED. HAVE INCLUDED SLIGHT CHANCES ALONG THE BOUNDARY OVERNIGHT. TEMPS WILL FINALLY COOL WITH PASSAGE OF BOUNDARY AND SHOULD FALL QUICKLY AFTER 01 TO 02Z ONCE SUN SETS AND DIURNAL COOLING COMMENCES. .LONG TERM.../WEDNESDAY THROUGH TUESDAY/... ISSUED AT 306 PM CDT TUE MAY 14 2013 FRONTAL BOUNDARY EXPECTED TO BE SOUTH OF STATE IN NORTHERN MISSOURI FOR BEGINNING OF PERIOD...WITH CHANCES FOR RAIN/THUNDER RETURNING ALONG FRONTAL BOUNDARY AS IT STALLS IN NORTHERN MISSOURI. MOISTURE INCREASES SOMEWHAT INTO WEDNESDAY AFTERNOON ACROSS THE SOUTH...AND HAVE INCLUDED CHANCES FOR THUNDER GENERALLY SOUTH OF INTERSTATE 80. HOWEVER...DO HAVE CONCERNS WITH THE AMOUNT OF MOISTURE AVAILABLE AS MODELS HAVE BEEN OVER AGGRESSIVE WITH MOISTURE LATELY...AND MAY BE TOO DRY IN LOWER LEVELS TO SEE PRECIPITATION. HOWEVER...AREA OF LOW PRESSURE WILL LIFT ACROSS THE DAKOTAS...WITH FRONTAL BOUNDARY ALSO LIFTING ACROSS REGION FOR LATE THURSDAY...WITH INCREASING MOISTURE IN SOUTHERLY FLOW AND WAA RETURNING...HAVE KEPT TEMPERATURES WARMER FOR WEDNESDAY AND THURSDAY...WITH INCREASING THUNDERSTORM CHANCES THURSDAY. BEST CHANCES LOOK TO BE THURSDAY NIGHT. SYSTEM WILL SLOWLY LIFT NORTHEAST...WITH LINGERING CHANCES FOR THUNDER THROUGH FRIDAY. MODELS CONTINUE TO POINT TO A BREAK BETWEEN SYSTEMS WITH FIRST LOWS INFLUENCE WAINING INTO SATURDAY BEFORE ANOTHER AREA OF LOW PRESSURE PUSHES EASTWARD FROM THE DAKOTAS. HAVE TRENDED POPS DOWN FOR FRIDAY NIGHT INTO SATURDAY. THIS SECONDARY SYSTEM LOOKS TO BE THE BEST POTENTIAL FOR SEVERE WEATHER...WHILE SOME AREAS OF HIGH CAPE NOTED FOR SATURDAY...LITTLE SHEAR AS FRONTAL BOUNDARY LAYS WELL TO THE WEST OF CENTRAL IOWA. HOWEVER...CAPE VALUES INCREASE ALONG WITH SHEAR FOR SUNDAY AS SYSTEM PUSHES ACROSS IOWA. HAVE INCREASED POPS FOR SUNDAY AFTERNOON. FRONT PUSHES SOUTH WITH LINGERING POPS FOR EARLY IN THE WEEK. HIGH PRESSURE WORKING IN FROM CANADA FOR END OF PERIOD BEHIND SYSTEM AND A RETURN TO CALM WEATHER. HOWEVER...TEMPERATURES WILL DROP BACK BELOW NORMAL FOR THE END OF THE PERIOD AS COLDER AIR WORKS IN WITH HIGH. && .AVIATION...14/18Z ISSUED AT 1233 PM CDT TUE MAY 14 2013 MAIN CONCERNS THIS PERIOD REMAIN WINDS AND POTENTIAL FOR SOME THUNDER FOR THE LATE AFTERNOON AND OVERNIGHT HOURS. WINDS CONTINUE STRONG NORTHWEST AND NORTH AREAS WHERE MIXED LAYER RAPIDLY REACHING FULL DEPTH EARLY THIS AFTERNOON. WILL CONTINUE TO SEE STRONG WINDS THROUGH 23Z DIMINISHING THEREAFTER. WITH MOISTURE POOLING OVER PORTIONS OF CENTRAL IOWA...SOME CONCERNS OF INSTABILITY THOUGH NO FOCUSING MECHANISM UNTIL BOUNDARY APPROACHES THIS EVENING. WITH BOUNDARY SOUTH OF AREA OVERNIGHT...SOME RETURN FLOW ALOFT SHOWS MORE PROMISE TO INITIATE SCATTERED CONVECTION OVER THE SOUTH. HAVE INCLUDED VCSH FOR KDSM AND KOTM...BUT OTHERWISE WILL KEEP DRY FOR THIS PERIOD UNTIL ANY BETTER ORGANIZATION SHOWS ITS HAND. && .FIRE WEATHER... ISSUED AT 306 PM CDT TUE MAY 14 2013 RELATIVE HUMIDITY VALUES WILL CONTINUE LOW THROUGH 7PM TODAY OVER WESTERN AND NORTHERN PORTIONS OF THE FORECAST AREA. RH VALUES RANGING FROM 13 TO 22 PERCENT AND SUSTAINED WINDS AROUND 25 MPH THROUGH EARLY EVENING. WILL CONTINUE RED FLAG WARNING THROUGH EVENING HOURS OR UNTIL WINDS DIMINISH. && .DMX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR ADAIR-ADAMS- AUDUBON-BOONE-CALHOUN-CARROLL-CASS-CERRO GORDO-CRAWFORD-DALLAS- EMMET-FRANKLIN-GREENE-GUTHRIE-HAMILTON-HANCOCK-HUMBOLDT-KOSSUTH- PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-WORTH-WRIGHT. && SHORT TERM...REV LONG TERM...AWB AVIATION...REV FIRE WEATHER...REV
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 527 AM CDT TUE MAY 14 2013 IAZ004>007-015>017-023>026-033>036-044>047-057>059-070-071-081- 151030- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-SAC-CALHOUN-WEBSTER-HAMILTON- CRAWFORD-CARROLL-GREENE-BOONE-AUDUBON-GUTHRIE-DALLAS-CASS-ADAIR- ADAMS- 527 AM CDT TUE MAY 14 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL AND NORTH CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT A RED FLAG WARNING IS IN EFFECT FOR THE AREA THIS AFTERNOON AND EARLY EVENING. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. ISOLATED NON SEVERE THUNDERSTORMS AREA POSSIBLE LATE THIS AFTERNOON AND EARLY EVENING. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY PERIODS OF THUNDERSTORMS ARE FORECAST THURSDAY THROUGH MONDAY...WITH THE BEST POTENTIAL FOR SEVERE WEATHER SATURDAY NIGHT INTO SUNDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AT TIMES LATE THIS WEEK AND INTO THE WEEKEND. IAZ027-028-037>039-048>050-060>062-072>075-082>086-092>097-151030- BUTLER-BREMER-HARDIN-GRUNDY-BLACK HAWK-STORY-MARSHALL-TAMA-POLK- JASPER-POWESHIEK-MADISON-WARREN-MARION-MAHASKA-UNION-CLARKE-LUCAS- MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS- 527 AM CDT TUE MAY 14 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND SOUTH CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. THE COMBINATION OF LOW HUMIDITY AND GUSTY SOUTHWEST WINDS AND STILL GREENING FUELS WILL LEAD TO AN ELEVATED FIRE DANGER TODAY. ISOLATED NON SEVERE THUNDERSTORMS ARE POSSIBLE TONIGHT. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A FEW THUNDERSTORMS ARE POSSIBLE FAR SOUTH WEDNESDAY THEN PERIODS THUNDERSTORMS ARE FORECAST THURSDAY THROUGH MONDAY...WITH THE BEST POTENTIAL FOR SEVERE WEATHER SATURDAY NIGHT INTO SUNDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AT TIMES LATE THIS WEEK AND INTO THE WEEKEND.
The Des Moines radar (KDMX), 111 km away, was scanning. The volume nearest the first event began at 21:43 UTC.
4 thunderstorm wind. Local standard time, as filed.
A trained spotter reported wind gusts estimated at 60 to 75 MPH along with a large dust cloud near a thunderstorm.
The Cerro Gordo County dispatch relayed a public report of strong winds blowing shingles off of a roof between Interstate 35 and Swaledale.
Reported at the Clarion AWOS site.
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, May 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: 439880, 439879, 439881, 439882.