A weak cold frontal boundary approached Iowa from the northwest as an upper level low pressure area reached the western border during the afternoon. The airmass became unstable with about 2000 J/kg of CAPE available.
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 weak cold frontal boundary approached Iowa from the northwest as an upper level low pressure area reached the western border during the afternoon. The airmass became unstable with about 2000 J/kg of CAPE available. Shear was around 40 kts by late afternoon. Surface temperatures rose into the low to mid 80s with dewpoint readings in the upper 60s to low 70s. The downdraft CAPE was quite high over northeast Iowa around 1000 J/kg to just above. Thunderstorms formed in an arching line ahead of the approaching upper low. Though most of the storms were not severe, one became severe in Bremer County with a wind gust of 65 MPH in the Plainfield area. Several trees were blown down and small hail also covered the ground. Thunderstorms continued to develop in the warm air advection zone. High winds damaged cars, a house, and trees in the Lake Mills area of Winnebago County. A funnel cloud was observed northwest of Fonda in Pocahontas County.
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 Aug 29, 2:15 PM CST, 1 hour 11 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 315 PM CDT FRI AUG 29 2014 .SHORT TERM /TONIGHT/... ISSUED AT 315 PM CDT FRI AUG 29 2014 ANOTHER ACTIVE NIGHT IS IN STORE AS THE DEEP LAYERED TROUGH FEATURE THAT HAS BEEN LINGERING TO OUR WEST THE LAST DAY OR TWO FINALLY PROGRESSES EASTWARD ACROSS IOWA. REGIONAL RADAR IMAGERY FROM THE LAST COUPLE OF HOURS SHOWS AN INCREASE IN COVERAGE OF SHOWERS AND THUNDERSTORMS AROUND THE BROAD CIRCULATION OF THE TROUGH COINCIDENT WITH DAYTIME HEATING MAX...BUT EXPECT SCATTERED TO NUMEROUS SHOWERS/STORMS TO PERSIST THROUGH THE EVENING AND INTO TONIGHT BEFORE FINALLY FADING OUT AND MOVING OFF TO THE EAST EARLY SATURDAY MORNING. HAVE MAINTAINED MOSTLY 50 TO 80 POPS THROUGH MIDNIGHT ACCORDINGLY. A HEAVY RAIN THREAT REMAINS PARTICULARLY CLOSER TO THE TROUGH AXIS WHERE CELL MOTION IS QUITE SLOW...HOWEVER THIS THREAT WILL BE ISOLATED AND NO WIDESPREAD FLOODING IS ANTICIPATED. LIKEWISE DIURNAL HEATING IN THE SUNNIER AREAS ACROSS OUR EASTERN SECTIONS THIS AFTERNOON HAS ALLOWED FOR IMPRESSIVE DESTABILIZATION AND THERE IS SOME POTENTIAL HERE FOR ISOLATED SEVERE WIND GUSTS...BUT AGAIN NO WIDESPREAD OR SIGNIFICANT SEVERE WEATHER IS ANTICIPATED. .LONG TERM /SATURDAY THROUGH FRIDAY/... ISSUED AT 315 PM CDT FRI AUG 29 2014 LONG AWAITED SHORT BREAK FROM THUNDERSTORMS TO ARRIVE EARLY SATURDAY...AS THIS WEEKS PERSISTENT UPPER LEVEL WAVE FINALLY MOVES OFF TO THE NORTHEAST. A WEAK WAVE BEHIND THIS SYSTEM MAY BRING SOME RESIDUAL CLOUDS OVER NORTHERN SECTIONS TOMORROW...BUT OVERALL A NICE CHANGE FROM THE THREAT FOR THUNDERSTORMS EVERYDAY. A SLIGHTLY COOLER AIRMASS WILL ARRIVE AS WELL WITH HIGHS IN THE UPPER 70S TO LOWER 80S...THOUGH HUMIDITY LEVELS WILL NOT CHANGE ALL THAT MUCH. A WEAK RIDGE OF HIGH PRESSURE WILL CROSS THE REGION SATURDAY NIGHT INTO EARLY SUNDAY MORNING. AS THE RIDGE RECEDES TO THE EAST...STRONGER SOUTHWEST FLOW WILL DEVELOP BOTH AT THE SFC AND ALOFT IN RESPONSE TO A RATHER STRONG H500 SHORT WAVE APPROACHING FROM THE WEST. AHEAD OF THE SYSTEM... DEW POINTS WILL QUICKLY RETURN TO THE 70S WITH HIGHS IN THE UPPER 80S TO NEAR 90 ACROSS THE SOUTH. WITH THE QUICK WARM UP... INSTABILITY...PRECIPITABLE WATER...AND WARM CLOUD DEPTHS WILL AGAIN RISE TO LEVELS OF CONCERN...WITH SEVERE STORM POTENTIAL INCREASING ACROSS THE WEST ALONG THE BOUNDARY FROM THE MID TO LATE AFTERNOON HOURS NORTHWEST TO CENTRAL IOWA IN THE EVENING. THOUGH WIND FIELDS ALOFT ARE NOT SIGNIFICANT...THERE HAS BEEN A CONSISTENT SIGNAL FOR 40 TO 50KT WINDS THROUGH THE COLUMN BY LATE DAY SUNDAY AND SUNDAY EVENING. PWATS ARE EXPECTED TO ONCE AGAIN POOL ALONG THE BOUNDARY AND INCREASE TO 1.75 TO 2.0 INCHES BY LATE DAY AND EVENING. WARM CLOUD DEPTHS AGAIN ARE MAXIMIZED TO NEARLY 13KFT BY LATE AFTERNOON WEST AND CENTRAL. CURRENT BUFR SOUNDINGS ACROSS THE REGION FOR 21Z SUNDAY SHOW A DRY LAYER THROUGH THE LOWER TO MID LEVELS WITH SOME VEERING WINDS WITH HEIGHT...THOUGH GENERALLY UNIDIRECTIONAL. LOOKING AT THE GFS 12Z MODEL DATA...0-3KM BULK SHEAR VECTORS BECOME MORE PERPENDICULAR TO THE EXPECTED LINE OF STORM DEVELOPMENT SUNDAY EVENING...SUGGESTING THAT BOWING LINEAR SEGMENTS AND A FASTER MOVING LINE OF STORMS WITH A GREATER POTENTIAL OF WIND DAMAGE MAY DEVELOP AFTER SOME INITIAL SUPERCELLS AND ANY LINEAR SEGMENTS MERGE. CURRENTLY THE AREA IS OUTLOOKED FOR A SLIGHT RISK FOR SEVERE WEATHER. THERE WILL BE A GOOD CHANCE EARLY IN THE EVENT OF HEAVY RAINFALL OF 1 TO +2 INCHES NEARER THE COOL FRONTAL BOUNDARY IN THE FAR WEST/NORTHWEST...AND EVEN WITH THE POTENTIAL OF FASTER MOVING STORMS IN THE MID TO LATE EVENING...RAINFALL RATES AND AMOUNTS MAY STILL BE ON THE MODERATE TO PERHAPS HEAVY SIDE DUE TO THE PERSISTENCE OF ELEVATED WARM CLOUD DEPTHS AND HIGH PWATS. ANY ADDITIONAL RAINFALL WILL AGAIN PUSH STREAMS AND RIVERS UP AND PERHAPS CAUSE SOME URBAN STREET OR FIELD FLOODING...BUT THE 36 HOUR BREAK FROM SATURDAY MORNING THROUGH 00Z SUNDAY WILL HELP MITIGATE THE SITUATION. BEYOND SUNDAY NIGHT...THERE REMAINS SLIGHTLY LESS CERTAINTY REGARDING NEXT WEEKS PATTERN...BUT TWO THEMES ARE BEGINNING TO EMERGE. FIRST...BOTH THE GFS/EURO SUGGEST AN ADDITIONAL FAST MOVING WAVE WITH SCT THUNDERSTORMS WILL CROSS THE REGION THE MONDAY NIGHT TUESDAY...PRIOR TO THE SOUTHEAST US H500 RIDGE BUILDING BACK WEST INTO THE SOUTHERN PLAINS AND MID MISSISSIPPI RIVER VALLEY. AS THE WESTERLIES RETREAT FARTHER NORTH...H500 HEIGHTS ARE EXPECTED TO BUILD FROM AROUND 580DM MONDAY TO NEARLY 592DM BY 00Z FRIDAY. TEMPS WILL WARM THROUGH THE PERIOD WITH A GENERAL SHIFT OF THE HEAVIER RAIN THREAT TO NORTHERN IOWA AND STATES NORTH. WILL CONTINUE TO MONITOR...AND HAVE MORE CONFIDENCE IN THE WARMING TEMPS THAN LACK OF THUNDERSTORMS...SO DO EXPECT TO SEE TEMPERATURES PUSHING TOWARD 90 DEGREES OVER CENTRAL AND SOUTH TOWARD THE END OF NEXT WEEK. OTHERWISE...MUCH OF THE UPCOMING WEEK WILL CONTINUE IN THE UPPER 70S TO 80S FROM MONDAY THROUGH WEDNESDAY WITH LOWS IN THE UPPER 50S TO 60S. && .AVIATION...29/18Z ISSUED AT 1241 PM CDT FRI AUG 29 2014 EXPECT MAINLY VFR CONDITIONS THIS AFTERNOON...DETERIORATING LATE AFTERNOON/EVENING AS SHRA/TSRA DEVELOP ACROSS THE AREA WITH LOCALIZED MVFR OR LOWER CONDITIONS...THEN DETERIORATING FURTHER OVERNIGHT EVEN AS PRECIP ENDS...WITH REDEVELOPMENT OF LOW CIGS/VSBYS IN BR ONCE AGAIN. HAVE TRENDED TAFS THIS WAY AND ATTEMPTED TO TIME MOST LIKELY PERIOD FOR TSRA AT DSM/ALO/OTM...WITH AMENDMENTS ANTICIPATED AS THE STORMS MOVE ACROSS THE AREA LATER TODAY. && .HYDROLOGY... ISSUED AT 315 PM CDT FRI AUG 29 2014 SIMILAR CONCERNS AS PAST FEW DAYS. MOST OF THE REGION CONTINUES NEARLY SATURATED...WITH SOME LOCATIONS NOT HAVING MUCH ROOM FOR ADDITIONAL RAINFALL BEFORE RUNOFF MAY BECOME A PROBLEM. SOUTHEAST COUNTIES OF OUR FORECAST AREA COULD TAKE A BIT MORE...FORTUNATELY THE CURRENT STORMS ARE WORKING NORTH ACROSS THESE LOCATIONS. ADDITIONAL RAINFALL LATER THIS EVENING COULD LEAD TO SOME ISOLATED PROBLEMS OVER THE WEST/SOUTHWEST WITH FIELD PONDING/MINOR FLOODING IN RURAL AND URBAN AREAS THE MAIN CONCERNS. WILL BE MONITORING FOR ANY MORE ORGANIZED THREAT THIS EVENING. BY SUNDAY EVENING...MORE WIDESPREAD MODERATE RAINFALL EXPECTED. WITH NEARLY 36 HOURS OF QUIET CONDITIONS EXPECTED FROM 12Z SAT THROUGH ABOUT 00Z SUNDAY... SOILS SHOULD BETTER BE ABLE TO HANDLE ADDITIONAL RAINFALL. SOME MINOR RIVER FLOODING CONTINUES NOW NEAR DSM AND POTENTIALLY SOME ADDITIONAL RIVERS/STREAMS RISING TO OR SLIGHTLY ABOVE FS OVER THE WEEKEND OR EARLY NEXT WEEK ACROSS THE AREA. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...LEE LONG TERM...REV AVIATION...LEE HYDROLOGY...REV
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 335 PM CDT FRI AUG 29 2014 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-302045- 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- 335 PM CDT FRI AUG 29 2014 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...THIS AFTERNOON AND TONIGHT THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND TONIGHT. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH THUNDERSTORMS...WITH UP TO AN INCH OR MORE OF RAIN POSSIBLE. SOME PONDING OF WATER IN FIELDS AND LOCALIZED STREET FLOODING IN URBAN AREAS MAY OCCUR WITH THE HEAVY RAINFALL. THERE IS A SMALL RISK OF LOCALIZED FLASH FLOODING BUT WIDESPREAD FLASH FLOODING IS NOT EXPECTED AT THIS TIME. IN ADDITION...ISOLATED SEVERE THUNDERSTORMS WILL BE POSSIBLE... ESPECIALLY IN THE SOUTHEAST...WITH DAMAGING WIND THE MAIN THREAT AND OR ISOLATED LARGE HAIL THE MAIN THREATS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THUNDERSTORM CHANCES WILL END VERY EARLY SATURDAY MORNING EAST AND RETURN ACROSS THE AREA SUNDAY EVENING THROUGH MONDAY MORNING. THUNDERSTORMS WILL BE CAPABLE OF HEAVY RAINFALL. A FEW SEVERE THUNDERSTORMS MAY BE POSSIBLE AT TIMES. THERE IS A MORE ORGANIZED THREAT FOR SEVERE WEATHER SUNDAY AFTERNOON THROUGH LATE SUNDAY EVENING WITH THE POTENTIAL OF WIND AND HAIL AND HEAVY RAINFALL THE MAIN THREATS. AN ISOLATED TORNADO IS ALSO POSSIBLE EARLY IN THE EVENING OVER THE WEST AND NORTHWEST. ADDITIONAL THUNDERSTORMS WILL BE POSSIBLE LATE MONDAY NIGHT AND TUESDAY AND AGAIN WEDNESDAY NIGHT AND THURSDAY. DURING THIS PERIOD...THE THREAT FOR SEVERE WEATHER APPEARS TO BE LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT LIKELY BE NEEDED THIS AFTERNOON AND TONIGHT. SPOTTER ACTIVATION MAY BE NEEDED FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING. REV
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
1029 AM CDT FRI AUG 29 2014
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 AM HEAVY RAIN ANKENY 41.72N 93.61W
08/29/2014 M2.89 INCH POLK IA CO-OP OBSERVER
2.89 INCHES OF RAIN.
0700 AM HEAVY RAIN NEWTON 41.70N 93.05W
08/29/2014 M2.83 INCH JASPER IA CO-OP OBSERVER
2.83 INCHES OF RAIN.
0700 AM HEAVY RAIN 2 WNW ANKENY 41.74N 93.64W
08/29/2014 E2.30 INCH POLK IA COCORAHS
2.30 INCHES OF RAIN.
0700 AM HEAVY RAIN 1 E CLIVE 41.61N 93.75W
08/29/2014 M2.27 INCH POLK IA NWS EMPLOYEE
NWS EMPLOYEE MEASURED 2.27 INCHES OF RAINFALL OVERNIGHT.
0700 AM HEAVY RAIN URBANDALE 41.64N 93.74W
08/29/2014 E3.00 INCH POLK IA PUBLIC
PUBLIC REPORT OF THREE INCHES OF RAIN IN URBANDALE
OVERNIGHT. RECEIVED VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN 6 S MADRID 41.79N 93.82W
08/29/2014 E2.35 INCH DALLAS IA COCORAHS
2.35 INCHES OF RAIN.
0700 AM HEAVY RAIN 3 NNW JOHNSTON 41.73N 93.72W
08/29/2014 E2.35 INCH POLK IA COCORAHS
2.35 INCHES OF RAIN.
0700 AM HEAVY RAIN 4 S NORWALK 41.44N 93.68W
08/29/2014 E3.19 INCH WARREN IA COCORAHS
3.19 INCHES OF RAIN.
0700 AM HEAVY RAIN 1 SE WINDSOR HEIGHTS 41.59N 93.70W
08/29/2014 E3.49 INCH POLK IA COCORAHS
3.49 INCHES OF RAIN.
0700 AM HEAVY RAIN 4 WNW DES MOINES 41.60N 93.69W
08/29/2014 E3.53 INCH POLK IA COCORAHS
3.53 INCHES OF RAIN.
0700 AM HEAVY RAIN POLK CITY 41.77N 93.72W
08/29/2014 E3.57 INCH POLK IA COCORAHS
3.57 INCHES OF RAIN.
0700 AM HEAVY RAIN MASSENA 41.25N 94.77W
08/29/2014 E4.90 INCH CASS IA CO-OP OBSERVER
4.90 INCHES OF RAIN.
0700 AM HEAVY RAIN ADEL 41.61N 94.03W
08/29/2014 E3.96 INCH DALLAS IA TRAINED SPOTTER
3.96 INCHES OF RAIN.
0700 AM HEAVY RAIN BONDURANT 41.69N 93.46W
08/29/2014 M2.68 INCH POLK IA CO-OP OBSERVER
2.68 INCHES OF RAIN.
0700 AM HEAVY RAIN DES MOINES 41.58N 93.62W
08/29/2014 E3.49 INCH POLK IA TRAINED SPOTTER
3.49 INCHES OF RAIN. NEAR WAVELAND GOLF COURSE.
0700 AM HEAVY RAIN WEST DES MOINES 41.57N 93.75W
08/29/2014 E3.60 INCH POLK IA PUBLIC
3.60 INCHES OF RAIN. RECEIVED VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN GREENFIELD 41.31N 94.46W
08/29/2014 E2.10 INCH ADAIR IA PUBLIC
2.10 INCHES OF RAIN. RECEIVED VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN NEWTON 41.70N 93.05W
08/29/2014 E2.20 INCH JASPER IA PUBLIC
2.20 INCHES OF RAIN. RECEIVED VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN WEST DES MOINES 41.57N 93.75W
08/29/2014 E2.35 INCH POLK IA PUBLIC
2.35 INCHES NEAR I35 AND MILLS CIVIC PARKWAY. VIA SOCIAL
MEDIA.
0700 AM HEAVY RAIN 1 N AMES 42.04N 93.63W
08/29/2014 E3.25 INCH STORY IA PUBLIC
3.25 INCHES OF RAIN. RECEIVED VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN WINTERSET 41.34N 94.02W
08/29/2014 E3.00 INCH MADISON IA PUBLIC
ESTIMATED 3.00 INCHES OF RAIN VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN EARLHAM 41.49N 94.12W
08/29/2014 E3.06 INCH MADISON IA PUBLIC
3.06 INCHES VIA SOCIAL MEDIA.
0700 AM HEAVY RAIN ANKENY 41.72N 93.61W
08/29/2014 E3.00 INCH POLK IA PUBLIC
ESTIMATED 3.00 INCHES VIA SOCIAL MEDIA.
&&
BFSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
315 PM CDT FRI AUG 29 2014
IAZ074-084-085-095-096-292100-
APPANOOSE IA-WAYNE IA-LUCAS IA-MARION IA-MONROE IA-
315 PM CDT FRI AUG 29 2014
...HEAVY RAIN AND GUSTY WINDS...
AT 313 PM CDT...DOPPLER RADAR WAS TRACKING A LINE OF STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM 5 MILES SOUTHEAST OF
CHARITON TO RATHBUN LAKE TO 3 MILES SOUTHEAST OF CENTERVILLE...AND
MOVING NORTH AT 40 MPH.
WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH THESE STORMS.
ONE TO TWO INCH RAINFALL RATES ARE EXPECTED WITH THESE STORMS.
LOCATIONS IMPACTED INCLUDE...
CENTERVILLE...CHARITON...ALBIA...MELCHER-DALLAS...LAKE SUNDOWN...
RATHBUN LAKE...MORAVIA...MOULTON...RUSSELL...LOVILIA...MYSTIC...
WILLIAMSON...HAMILTON...MELROSE...UNIONVILLE...RATHBUN...PLANO...
MARYSVILLE...UDELL AND ALBIA MUNICIPAL AIRPORT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
TORRENTIAL RAINFALL IS OCCURRING WITH THESE STORMS...AND MAY LEAD TO
FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED ROADWAYS.
FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THESE STORMS.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.
&&
LAT...LON 4087 9334 4135 9333 4118 9287 4116 9287
4116 9282 4109 9264 4059 9264
TIME...MOT...LOC 2013Z 179DEG 35KT 4096 9322 4086 9299 4070 9282
PODRAZIKThe La Crosse radar (KARX), 154 km away, was scanning. The volume nearest the first event began at 21:27 UTC.
2 thunderstorm wind, 1 funnel cloud. Local standard time, as filed.
Public reported trees down along with small hail covering the ground. Wind gusts of 65 MPH were recorded at an RWIS site.
KIMT TV reported damages to cars, a house, and to trees by high winds from a thunderstorm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2014Every state in 2014This day in weather historyWarnings in Iowa, August 2014
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: 531459, 531460, 531472.