Heavy rainfall of 3 to 7 inches caused areal flooding in Cherokee and Plymouth Counties in northwest Iowa from August 17th to August 19th. Heavy rain also caused flooding of the West Fork Little Sioux/Ditch in Woodbury County.
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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 FSD wrote it up.
Heavy rainfall of 3 to 7 inches caused areal flooding in Cherokee and Plymouth Counties in northwest Iowa from August 17th to August 19th. Heavy rain also caused flooding of the West Fork Little Sioux/Ditch in Woodbury 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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Aug 17, 5:25 AM CST, 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SIOUX FALLS SD 625 AM CDT MON AUG 17 2015 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 348 AM CDT MON AUG 17 2015 MAIN CONCERNS IN THE SHORT TERM PORTIONS OF THE FORECAST ARE FOCUSED ON RAIN CHANCES TODAY AND TONIGHT. AFTER A SOGGY SUNDAY EVENING AND OVERNIGHT...MINOR SHORTWAVE ENERGY CONTINUES TO SLOWLY SLIDE EAST ACROSS PORTIONS OF NORTHERN IOWA. IN THE LOW-LVLS...925:850 BAROCLINIC ZONE REMAINS SPRAWLED FROM SW TO NE ACROSS THE SOUTHEASTERN THIRD OF THE CWA THIS MORNING. WHILE LOW-LVL FLOW IS BEGINNING TO VEER SLIGHTLY...ALREADY SEEING ENHANCED CONVERGENCE ON THIS BOUNDARY AID IN THE REDEVELOPMENT OF SHOWERS ALONG THE MO RIVER CORRIDOR. ANTICIPATING THAT THIS CONVERGENT ZONE WILL ONLY SLOWLY DRIFT SOUTHEAST THIS MORNING...AND WILL CONTINUE TO ADVERTISE POPS ALONG THE SOUTHERN THIRD OF THE CWA THROUGH MID-MORNING. THE NEXT WAVE OF ENERGY IS ALREADY POISED TO ENTER THE WESTERN DAKOTAS BY MID-AFTERNOON...WITH MODELS SHOWING INCREASING ISENTROPIC LIFT BY MID AND ESPECIALLY LATE AFTERNOON AS LOW-LVL FLOW BACKS. SHOULD SEE SHOWERS AND A FEW THUNDERSTORMS MIXED IN THROUGH THE EVENING HOURS WITH THE BEST ACTIVITY FOCUSED OVER THE BLACK HILLS REGION AND AGAIN FURTHER SOUTH ALONG THE SFC BOUNDARY IN SOUTHERN NE/IA. NOT A TON OF INSTABILITY AS THIS NEXT WAVE MOVES IN...SO WOULD EXPECT RAINFALL RATES TO STAY ON THE LOWER SIDE. HOWEVER WITH PWAT VALUES NEARLY 150 PERCENT OF NORMAL...LOCALLY HEAVY RAIN COULD BE POSSIBLE INTO TUESDAY MORNING. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 348 AM CDT MON AUG 17 2015 ROBUST UPPER LEVEL WAVE WILL BE DROPPING THROUGH THE AREA ON TUESDAY THROUGH TUESDAY NIGHT BEFORE LIFTING OFF TO THE NORTHEAST ON WEDNESDAY. PRECIPITABLE WATER VALUES WILL BE LOWER THAN RECENTLY BUT STILL AT OR ABOVE SEASONAL NORMALS WITH VALUES AVERAGING AROUND 1.5 INCHES. WITH THE WAVE CIRCLING THE BOTTOM OF THE LONG WAVE TROUGH RIGHT OVER THE CWA...LOOKS LIKE ANOTHER PROLONGED PERIOD OF LIGHT TO MODERATE RAIN AS IT WILL TAKE QUITE A WHILE BEFORE THINGS CLEAR THE AREA WEDNESDAY EVENING. THURSDAY AND FRIDAY LOOK LIKE DRY AND PLEASANT DAYS AS HIGH PRESSURE SLIDES ACROSS THE AREA WITH TEMPERATURES WARMING BACK UP CLOSER TO SEASONAL NORMALS. THE NEXT WAVE TO DIG SOUTHWARD IN THE NORTHERN STREAM FROM THE PACIFIC NORTHWEST SHOULD START TO IMPACT THE AREA FRIDAY NIGHT AND INTO THE WEEKEND...WITH SATURDAY AND SATURDAY EVENING SHAPING UP AS POTENTIALLY ACTIVE WITH AT LEAST THE POTENTIAL FOR MORE LOCALLY HEAVY RAINS. THIS WAVE APPEARS TO BE ON TRACK TO STAY A LITTLE FURTHER NORTH AND BE MORE PROGRESSIVE THAN THE ONE TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 622 AM CDT MON AUG 17 2015 ANTICIPATING SHOWERS TO CONTINUE INTO THE MID-MORNING HOURS...IMPACTING PRIMARILY KSUX. OTHERWISE...CEILINGS THIS MORNING HAVE DROPPED INTO THE IFR TO LIFR RANGE FROM FSD TO SUX. CEILINGS WILL GRADUALLY LIFT THROUGH THE DAY...BUT MVFR CEILINGS MAY LINGER AT KSUX THROUGH MUCH OF THE MORNING. REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS LATER TODAY REMAINS VERY DIFFICULT TO TIME OUT. CANNOT RULE OUT WIDELY SCATTERED AFTERNOON SHOWERS...BUT COVERAGE VERY UNCERTAIN ATTM. BEST CHANCES FOR RAIN ARRIVE LATER THIS EVENING AND CONTINUE OVERNIGHT. && .HYDROLOGY... ISSUED AT 348 AM CDT MON AUG 17 2015 SEVERAL AREAS OF 3 TO 5 PLUS INCHES OF RAIN FROM SATURDAY NIGHT THROUGH EARLY THIS MORNING. ONE IS AROUND THE WORTHINGTON TO WINDOM AREA IN SOUTHWEST MINNESOTA. THE OTHERS AND IN NORTHWEST IOWA. LUCKILY THESE AREAS HAD BEEN FAIRLY DRY FOR THE LAST COUPLE WEEKS AND THERE DOES NOT APPEAR TO BE ANY RUNOFF FROM THESE RAINS THAT WILL CAUSE AREA RIVERS TO THREATEN FLOODING. HOWEVER...MANY SMALLER STREAMS ARE LIKELY CLOSE TO BANKFULL...AND MANY FIELDS AND DITCHES LIKELY HAVE PONDED WATER FROM THE EARLIER RAINS. WITH THE POTENTIAL FOR ADDITIONAL MODERATE TO HEAVY RAIN FOR THE NEXT 48 HOURS...WILL BE WATCHING FOR POTENTIAL RIVER FLOOD ISSUES...AS WELL AS POTENTIAL FLASH FLOODING IF HEAVIER RAINS TUESDAY AND TUESDAY NIGHT MOVE INTO THE SAME AREAS THAT ARE NOW MUCH MORE SATURATED. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...DUX LONG TERM...MG AVIATION...DUX HYDROLOGY...MG
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 522 AM CDT MON AUG 17 2015 SDZ038>040-050-052>055-057>061-063>065-181030- BEADLE-KINGSBURY-BROOKINGS-GREGORY-JERAULD-SANBORN-MINER-LAKE- BRULE-AURORA-DAVISON-HANSON-MCCOOK-CHARLES MIX-DOUGLAS-HUTCHINSON- 522 AM CDT MON AUG 17 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL SOUTH DAKOTA...SOUTH CENTRAL SOUTH DAKOTA AND SOUTHEAST SOUTH DAKOTA. .DAY ONE...TODAY AND TONIGHT SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED THROUGH THIS EVENING...BECOMING MORE WIDESPREAD OVERNIGHT. SEVERE WEATHER IS NOT EXPECTED AT THIS TIME...BUT INDIVIDUAL STRONG CELLS COULD PRODUCE SOME ISOLATED HEAVY RAIN OVER A FEW SPOTS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY RAINFALL WITH EMBEDDED THUNDERSTORMS ARE EXPECTED THROUGH TUESDAY NIGHT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL LIKELY NOT BE NEEDED TODAY OR TONIGHT. MNZ071-072-080-097-098-SDZ056-062-066>070-181030- LINCOLN MN-LYON MN-MURRAY-PIPESTONE-ROCK-MOODY-MINNEHAHA-TURNER- LINCOLN SD-BON HOMME-YANKTON-CLAY SD- 522 AM CDT MON AUG 17 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST MINNESOTA...EAST CENTRAL SOUTH DAKOTA AND SOUTHEAST SOUTH DAKOTA. .DAY ONE...TODAY AND TONIGHT SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED THROUGH THIS EVENING...BECOMING MORE WIDESPREAD OVERNIGHT. SEVERE WEATHER IS NOT EXPECTED AT THIS TIME...BUT INDIVIDUAL STRONG CELLS COULD PRODUCE SOME ISOLATED HEAVY RAIN OVER A FEW SPOTS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY WIDESPREAD RAINFALL WITH EMBEDDED THUNDERSTORMS ARE EXPECTED THROUGH TUESDAY NIGHT. THERE IS A MARGINAL RISK OF SEVERE STORMS TUESDAY AFTERNOON AND EVENING...AND ADDITIONAL HEAVY RAINFALL IS ALSO POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL LIKELY NOT BE NEEDED TODAY OR TONIGHT. IAZ001>003-012>014-020>022-031-032-MNZ081-089-090-NEZ013-014- SDZ071-181030- LYON IA-OSCEOLA-DICKINSON-SIOUX-O'BRIEN-CLAY IA-PLYMOUTH-CHEROKEE- BUENA VISTA-WOODBURY-IDA-COTTONWOOD-NOBLES-JACKSON-DIXON-DAKOTA- UNION- 522 AM CDT MON AUG 17 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST IOWA...SOUTHWEST MINNESOTA...NORTHEAST NEBRASKA AND SOUTHEAST SOUTH DAKOTA. .DAY ONE...TODAY AND TONIGHT SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED THROUGH THIS EVENING...BECOMING MORE WIDESPREAD OVERNIGHT. SEVERE WEATHER IS NOT EXPECTED AT THIS TIME...BUT INDIVIDUAL STRONG CELLS COULD PRODUCE SOME ISOLATED HEAVY RAIN OVER A FEW SPOTS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY WIDESPREAD RAINFALL WITH EMBEDDED THUNDERSTORMS IS EXPECTED THROUGH TUESDAY NIGHT. THERE IS A SLIGHT RISK OF SEVERE STORMS TUESDAY AFTERNOON AND EVENING...AND ADDITIONAL HEAVY RAINFALL IS ALSO POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS POSSIBLE THIS AFTERNOON AND EVENING.
The national radar mosaic for the moment the first event began.
4 flood. Local standard time, as filed.
Heavy rainfall of 3 to 7 inches caused areal flooding of farmland, ditches, and several roads.
Heavy rainfall of 3 to 7 inches caused areal flooding of farmland, ditches, and several roads.
Flooding of the West Fork Little Sioux River caused flooding of farmland and a few roads. The river crested at 1.93 feet above flood stage near Moville on August 18th.
Flooding of the West Fork Ditch caused flooding of farmland and a few roads. The river crested at 3.7 feet above flood stage near Hornick on August 18th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2015Every state in 2015This day in weather historyWarnings in Iowa, August 2015
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: 598719, 598721, 598724, 598727.