Flash Flooding and Flooding in Iowa, August 27 to 31, 2015

Name: Flash Flooding and Flooding in Iowa, August 27 to 31, 2015
Start: 2015-08-27T20:00
End: 2015-08-31T23:59
Location: Iowa

August 27 to 31, 2015 · NWS DMX · 78 events in 15 counties and zones

In the hours after midnight on the 28th a low pressure system was over portions of central/eastern Nebraska moving toward Iowa. A warm front extended east out of the surface low into southern Iowa.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $2.0 million
Crop damage: $300,000
Events: 78

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.

What happened

The episode as NWS DMX wrote it up.

In the hours after midnight on the 28th a low pressure system was over portions of central/eastern Nebraska moving toward Iowa. A warm front extended east out of the surface low into southern Iowa. With the progression of the surface low, moderate to heavy rainfall began to enter the state. Areas that reported the greatest storm total amounts began to see rain around the 2 to 3 am hour and onward through the morning and into the early afternoon as the warm front lingered in central Iowa. In the end, numerous locations reported total rainfall amounts greater than 4 inches with a handful of reports around 6 inches. The greater totals were in excess of 9 inches and were recorded in Webster and Hamilton counties, with Dayton in Webster county taking the prize at 9.75 inches. The heavy rainfall allowed many rivers in central Iowa to rise above flood stage. Some of the flooding continued into early September. The entry will be continued in the September 2015 report.

What forecasters said that day

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 27, 2:32 PM CST, 5 hours 28 minutes earlier.

Area forecast discussion, Aug 27, 2:32 PM CST, 5 hours 28 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
332 PM CDT THU AUG 27 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 332 PM CDT THU AUG 27 2015

PRIMARY CONCERN IS INCOMING UPPER LEVEL SHORTWAVE AND THE
TIMING...EXTENT...AND MAGNITUDE OF PRECIPITATION THIS
EVENING/OVERNIGHT AND ONWARD THROUGH FRIDAY. LARGE SCALE
MODELS...NAM/GFS/EURO...HAVE ALL BEEN CONSISTENT IN PLACING NRN
IA/SRN MN UNDER THE GUN FOR HEAVY PRECIP...WHILE THE HIGHER RES
MODELS...NMM/ARW...WERE HOT ON CENTRAL IA PRIOR TO MOVING NORTH IN
THE MOST RECENT RUNS.  WITH THE MODELS IN BETTER AGREEMENT...HAVE
KEPT THE BULLS EYE NORTH OF AMES. FORCING IS OF NO QUESTION WITH
THIS SYSTEM WITH A STRONG WAA/THETA-E PUSH...ASSOCIATED VORTICITY
WITH THE APPROACH OF THE SURFACE LOW...AND AN EXTRA BOOST FROM THE
LLJ THIS EVENING AND OVERNIGHT. AN INITIAL PUSH OF SHOWERS/STORMS
MAY AFFECT NORTHERN IOWA THIS EVENING AS A WEAKER WAA/THETA-E PUSH
MOVES THROUGH AHEAD OF THE MAIN SHOW AROUND 3-6Z. THE MAIN SHOW WILL
BEGIN TO PUSH INTO THE CWA AROUND 6-9ZZ. WITH HI-RES MODELS NOTING
SOME WEAK CAPE IN PLACES OVERNIGHT...PRECIP WILL LIKELY BE MOSTLY
CONVECTIVE AND ELEVATED INITIALLY WITH DRY AIR REMAINING IN THE
LOWEST 3KM. PWATS IN THE 1.5-2.0 INCH RANGE GIVE FURTHER CONCERN FOR
HEAVY PRECIP...AND IN ALL...WOULD NOT BE SURPRISED TO BE SEE RATHER
WIDESPREAD 2 INCH REPORTS ACROSS THE NORTHWEST AND NORTHERN THIRDS
OF THE STATE AND EVEN DOWN TOWARDS AMES WITH LOCALLY HEAVY RAINFALL
TOWARDS 3+ INCHES. GIVEN THAT...FLASH FLOODING AND RIVERS/STREAMS
MAY BE OF CONCERN IN A FEW AREAS. RECENTLY DRY WEATHER AND HEALTHY
CROPS WILL LIKELY CURB MOST NON-URBAN FLASH FLOODING ISSUES...BUT
EXCESS RUNOFF FROM HEAVY PRECIP MAY MOVE THE MAIN CONCERNS TO SMALL
STREAMS AND RIVERS.

.LONG TERM /FRIDAY THROUGH THURSDAY/...
ISSUED AT 332 PM CDT THU AUG 27 2015

FOCUS ESSENTIALLY WILL BE ON THE FIRST 12-18 HOURS OF THE
FORECAST AS SYSTEM CROSSES THE STATE. AT BEGINNING OF THE
PERIOD...STRONG MOISTURE TRANSPORT WILL BE ONGOING INTO THE STATE
ON LLJ OF 55KTS AHEAD OF SURFACE/850MB LOW MOVING INTO WESTERN
IOWA. THIS WILL BE IMPACTING A BAROCLINIC ZONE ACROSS NORTHERN
IOWA AND SUPPORTED IN THE MID LEVEL BY DECENT KINEMATIC FORCING.
THIS WILL SUPPORT WIDESPREAD RAINFALL WITH EMBEDDED CONVECTIVE
ELEMENTS ALTHOUGH OVERALL INSTABILITY WILL BE QUITE WEAK. PWATS
GENERALLY 1.75-2.00 INCHES AND GENERALLY A DEEP WARM CLOUD LAYER
WITH WARM RAIN PROCESSES. ANTICIPATE MODERATE TO HEAVY RAINFALL TO
BE ONGOING AND TRANSLATING EASTWARD WITH THE UPPER SYSTEM DURING
THE MORNING. QPF IN THE MORNING WILL GENERALLY BE AROUND AN INCH
ACROSS THE NORTH IN THE MORNING ON TOP OF WHAT THE RECEIVE
OVERNIGHT. BY AFTERNOON...THE PRIMARY FORCING WILL BE SHIFTING
EASTWARD WITH HEAVIER PRECIPITATION IN THE NORTH PASSING INTO
WISCONSIN. HOWEVER...INSTABILITY FARTHER TO THE SOUTH AND
SOUTHWEST WILL INCREASE DURING THE AFTERNOON NEAR THE SURFACE LOW
AND MAY SEE SOME STRONG CONVECTION ACROSS THE SOUTHEAST THIRD OF
THE FORECAST AREA BY AFTERNOON. THIS THREAT WILL COME TO AN END
ACROSS THE SOUTHEAST ON FRIDAY EVENING WITH DRIER CONDITIONS LATER
FRIDAY NIGHT AND EVEN SOME CLEARING ACROSS CENTRAL IOWA. THIS MAY
ALLOW FOR FOG FORMATION...ESPECIALLY WEST OF I35 OVERNIGHT AS
WINDS WEAKEN AND LOW LEVEL WILL BE MOIST FROM THE RECENT RAINFALL.

THEREAFTER...UPPER RIDGING BUILDS INTO THE REGION AND REMAINS
GENERALLY IN PLACE FOR THE REMAINDER OF THE LONG TERM. THIS WILL
KEEP CONDITIONS DRY WITH TEMPERATURES THAT WILL MAKE IT FEEL LIKE
SUMMER ONCE AGAIN.

&&

.AVIATION...28/00Z
ISSUED AT 647 PM CDT THU AUG 27 2015

MVFR CONDITIONS WITH LOCAL IFR CONDITIONS EXPECTED AFT 06Z THROUGH
MUCH OF AT LEAST FRIDAY MORNING AS UPPER LEVEL SHORTWAVE AND
ATTENDANT SURFACE LOW LIFT ACROSS IOWA.  SFC FLOW WILL BE S TO SE AT
10-15KTS AHEAD OF THE LOW THEN SWITCH AROUND TO THE TO THE NORTH OR
NW ACROSS WESTERN TAF LOCATIONS VERY LATE IN THE FCST PD.

&&

.HYDROLOGY...
ISSUED AT 332 PM CDT THU AUG 27 2015

MODERATE TO HEAVY RAINFALL EVENT EXPECTED OVER THE NEXT 36 HRS IS
EXPECTED TO RESULT IN SIGNIFICANT WITHIN-BANK RISES ON MANY AREA
RIVERS. THE GREATEST RISES ARE EXPECTED WITHIN MIDDLE TO UPPER
PORTIONS OF THE DES MOINES...SKUNK...CEDAR AND IOWA RIVER BASINS. AT
THIS TIME...USING QPF FOR THE FULL EVENT DOES NOT BRING ANY RIVER
FORECAST POINTS TO FLOOD STAGE. SOME LOCATIONS DO RISE WITHIN 2 TO 3
FT OF FLOOD STAGE HOWEVER. ANTECEDENT SOIL CONDITIONS ARE EXPECTED
TO HELP MITIGATE SIGNIFICANT RUNOFF ISSUES.

THERE WILL BE A FLASH FLOOD RISK HOWEVER WITH THIS EVENT...
ESPECIALLY IN URBAN AREAS WELL AS OTHER FLOOD-PRONE LOCATIONS. AT
THIS TIME...EXTENT OF FLASH FLOODING IS NOT EXPECTED TO BE
WIDESPREAD ENOUGH TO WARRANT A FLASH FLOOD WATCH. WEATHER TRENDS
WILL CONTINUE BE MONITORED...HOWEVER.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

SHORT TERM...CURTIS
LONG TERM...COGIL
AVIATION...FAB
HYDROLOGY...ZOGG

Hazardous weather outlook, Aug 27, 2:44 PM CST, 5 hours 16 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
344 PM CDT THU AUG 27 2015

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-281100-
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-
344 PM CDT THU AUG 27 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORM INTO WESTERN AND NORTHERN IOWA TONIGHT.
THE SEVERE WEATHER THREAT IS LOW...HOWEVER LOCALLY HEAVY RAINFALL
IS POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

NON-SEVERE THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO FRIDAY.
LOCALLY HEAVY RAINFALL IS EXPECTED WITH RISES ON RIVERS AND
STREAMS POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED...HOWEVER RAINFALL REPORTS
WOULD BE APPRECIATED.

The radar

The Des Moines radar (KDMX), 52 km away, was scanning. The volume nearest the first event began at 01:59 UTC.

Open the radar archive at this moment

Event by event

53 heavy rain, 13 flash flood, 11 flood, 1 lightning. Local standard time, as filed.

Heavy Rain, Story

When: August 27, 8:00 PM CST to August 28, 8:00 PM CST
Where: Story County, Roland
Reported by: Social Media
Coordinates: 42.170, -93.500

Public reported heavy rainfall total of 3.80 inches over the last 24 hours.

Heavy Rain, Pocahontas

When: August 27, 9:00 PM CST to August 28, 12:00 PM CST
Where: Pocahontas County, 0.69 mi N of Pocahontas
Reported by: Social Media
Coordinates: 42.740, -94.670

Public reported heavy rainfall of 3.25 inches. End time radar estimated.

Heavy Rain, Webster

When: August 27, 10:00 PM CST to August 28, 2:15 PM CST
Where: Webster County, 0.69 mi N of Otho
Reported by: Social Media
Coordinates: 42.430, -94.150

Public reported heavy rainfall of 4.25 for an event total thus far.

Heavy Rain, Webster

When: August 27, 10:00 PM CST to August 28, 4:00 PM CST
Where: Webster County, 1.23 mi NW of Ft Dodge
Reported by: Mesonet
Coordinates: 42.510, -94.200

USGS stream gauge site reported heavy rainfall of 3.98 inches.

Heavy Rain, Webster

When: August 27, 10:00 PM CST to August 28, 5:30 PM CST
Where: Webster County, 1.02 mi W of (Fod)ft Dodge Muni A
Reported by: AWOS
Coordinates: 42.550, -94.200

Fort Dodge Regional Airport AWOS station reported heavy rainfall of 3.35 inches event total so far.

Heavy Rain, Webster

When: August 27, 10:15 PM CST to August 28, 11:45 AM CST
Where: Webster County, 0.69 mi S of Dayton
Reported by: Social Media
Coordinates: 42.260, -94.070

Public reported their rain gauge overflowed at 7.5 inches. Exact rainfall total unknown.

Heavy Rain, Webster

When: August 27, 10:15 PM CST to August 28, 1:29 PM CST
Where: Webster County, Dayton
Reported by: Social Media
Coordinates: 42.270, -94.070

Public reported heavy rainfall of 9 inches for the storm total.

Heavy Rain, Webster

When: August 27, 10:15 PM CST to August 28, 1:56 PM CST
Where: Webster County, 0.69 mi S of Dayton
Reported by: Social Media
Coordinates: 42.260, -94.070

Public reported updated rainfall total of 8.50 inches for the event.

Heavy Rain, Webster

When: August 27, 10:15 PM CST to August 28, 6:45 PM CST
Where: Webster County, 0.69 mi S of Dayton
Reported by: Social Media
Coordinates: 42.260, -94.070

Public reported heavy rainfall of 9.75 inches event total.

Heavy Rain, Calhoun

When: August 27, 10:30 PM CST to August 28, 12:00 PM CST
Where: Calhoun County, Rockwell City
Reported by: Social Media
Coordinates: 42.400, -94.630

Public reported heavy rainfall of approximately 7.50 inches. Photo posted from the KCCI ULocal page. End time radar estimated.

Heavy Rain, Webster

When: August 27, 11:00 PM CST to August 28, 12:01 PM CST
Where: Webster County, 3.57 mi E of Lehigh
Reported by: Trained Spotter
Coordinates: 42.370, -93.980

Trained spotter reported heavy rainfall of 6.5 inches measured from midnight through noon.

Heavy Rain, Hamilton

When: August 27, 11:15 PM CST to August 28, 1:35 PM CST
Where: Hamilton County, 0.69 mi N of Stanhope
Reported by: Mesonet
Coordinates: 42.290, -93.800

City of Ames alert station reported heavy rainfall of 6.20 inches since 5am.

Heavy Rain, Hamilton

When: August 27, 11:15 PM CST to August 28, 2:30 PM CST
Where: Hamilton County, 2.04 mi W of Stanhope
Reported by: Social Media
Coordinates: 42.280, -93.840

Public reported heavy rainfall of 6.00 inches event total. Rain gauge was full at the time as well.

Heavy Rain, Webster

When: August 27, 11:15 PM CST to August 28, 2:50 PM CST
Where: Webster County, 0.51 mi W of Duncombe
Reported by: Social Media
Coordinates: 42.470, -93.990

Public reported heavy rainfall of 3.25 inches of heavy rain for an event total so far.

Heavy Rain, Hamilton

When: August 27, 11:15 PM CST to August 28, 5:00 PM CST
Where: Hamilton County, Webster City
Reported by: Mesonet
Coordinates: 42.470, -93.820

Webster city mesonet station reported heavy rainfall of 4.49 inches.

Heavy Rain, Story

When: August 27, 11:30 PM CST to August 28, 12:53 PM CST
Where: Story County, 0.69 mi N of Story City
Reported by: Social Media
Coordinates: 42.190, -93.600

Public reported heavy rainfall of 4.25 inches.

Heavy Rain, Hamilton

When: August 27, 11:30 PM CST to August 28, 1:15 PM CST
Where: Hamilton County, 0.86 mi NE of Jewell
Reported by: Social Media
Coordinates: 42.310, -93.640

Public reported heavy rainfall of 5.06 inches.

Heavy Rain, Story

When: August 27, 11:30 PM CST to August 28, 1:35 PM CST
Where: Story County, 0.69 mi N of Story City
Reported by: Fire Department/Rescue
Coordinates: 42.190, -93.600

Story City Fire Department reported storm total heavy rainfall of 5.50 inches.

Heavy Rain, Hamilton

When: August 27, 11:30 PM CST to August 28, 2:20 PM CST
Where: Hamilton County, 3.58 mi W of Jewell
Reported by: Social Media
Coordinates: 42.300, -93.720

Public reported heavy rainfall of 9.50 inches for an event total thus far.

Heavy Rain, Hamilton

When: August 27, 11:30 PM CST to August 28, 2:20 PM CST
Where: Hamilton County, 0.86 mi NE of Jewell
Reported by: Social Media
Coordinates: 42.310, -93.640

Public reported heavy rainfall of 6.00 inches event total so far.

Heavy Rain, Hamilton

When: August 28, 12:00 AM CST to 11:50 AM CST
Where: Hamilton County, 2.9 mi ESE of Ellsworth
Reported by: Trained Spotter
Coordinates: 42.300, -93.530

Trained spotter reported 1.5 inches of rainfall in the past 2 hours with visibility less than 1/4 mile due to heavy rain.

Heavy Rain, Boone

When: August 28, 12:00 AM CST to 12:16 PM CST
Where: Boone County, 0.51 mi W of Boone Muni Arpt
Reported by: Emergency Manager
Coordinates: 42.050, -93.860

Emergency Manager reported isolated amounts measured in northern Boone county of 5.00 inches of heavy rainfall since midnight. Some county roads in northern Boone have water over them as well.

Heavy Rain, Hardin

When: August 28, 12:30 AM CST to 12:57 PM CST
Where: Hardin County, 0.69 mi S of Eldora
Reported by: Social Media
Coordinates: 42.360, -93.100

Public reported heavy rainfall of 3.50 inches.

Heavy Rain, Hardin

When: August 28, 12:30 AM CST to 2:00 PM CST
Where: Hardin County, 0.69 mi S of Steamboat Rock
Reported by: Mesonet
Coordinates: 42.410, -93.070

Mesonet report of heavy rainfall of 5.24 inches through 3 pm.

Heavy Rain, Hardin

When: August 28, 12:30 AM CST to 3:45 PM CST
Where: Hardin County, 0.69 mi S of Eldora
Reported by: Trained Spotter
Coordinates: 42.360, -93.100

Trained spotter reported heavy rainfall of 5.00 inches.

Heavy Rain, Hardin

When: August 28, 12:30 AM CST to 4:10 PM CST
Where: Hardin County, 0.69 mi S of Ackley
Reported by: Mesonet
Coordinates: 42.540, -93.050

USACE stream gauge reported heavy rainfall of 5.35 inches event total so far.

Heavy Rain, Hardin

When: August 28, 12:30 AM CST to 6:45 PM CST
Where: Hardin County, 0.69 mi S of Eldora
Reported by: Public
Coordinates: 42.360, -93.100

Public reported heavy rainfall of 5.40 inches.

Heavy Rain, Grundy

When: August 28, 1:00 AM CST to 2:35 PM CST
Where: Grundy County, 0.51 mi W of Wellsburg
Reported by: Trained Spotter
Coordinates: 42.430, -92.930

Trained spotter reported heavy rainfall of 5.10 inches event total so far.

Heavy Rain, Grundy

When: August 28, 1:00 AM CST to 5:00 PM CST
Where: Grundy County, 0.69 mi S of Grundy Center
Reported by: Social Media
Coordinates: 42.360, -92.770

Public reported heavy rainfall of 3.90 inches event total so far.

Heavy Rain, Butler

When: August 28, 1:15 AM CST to 5:00 PM CST
Where: Butler County, 0.69 mi N of Parkersburg
Reported by: Social Media
Coordinates: 42.580, -92.780

Public reported heavy rainfall of 4.50 inches event total so far.

Heavy Rain, Butler

When: August 28, 1:15 AM CST to 8:45 PM CST
Where: Butler County, Parkersburg
Reported by: Social Media
Coordinates: 42.570, -92.780

Public reported heavy rainfall of 5.40 inches event total with light rain ongoing.

Heavy Rain, Greene

When: August 28, 1:30 AM CST to 3:00 PM CST
Where: Greene County, 0.86 mi SE of Paton
Reported by: Trained Spotter
Coordinates: 42.160, -94.260

Trained spotter reported heavy rainfall of 4.00 inches so far today.

Heavy Rain, Butler

When: August 28, 1:30 AM CST to 4:15 PM CST
Where: Butler County, New Hartford
Reported by: Trained Spotter
Coordinates: 42.570, -92.620

Trained spotter reported heavy rainfall of 2.94 inches along with minor street flooding around town. Street flooding is worse to the SE in Dike.

Heavy Rain, Grundy

When: August 28, 1:30 AM CST to 4:30 PM CST
Where: Grundy County, 0.86 mi SE of Conrad
Reported by: Social Media
Coordinates: 42.220, -92.870

Public reported heavy rainfall of 3.20 inches event total.

Heavy Rain, Black Hawk

When: August 28, 1:30 AM CST to 4:30 PM CST
Where: Black Hawk County, 1.47 mi SSW of Hudson
Reported by: Trained Spotter
Coordinates: 42.400, -92.460

Trained spotter reported heavy rainfall total of 2.90 inches.

Heavy Rain, Black Hawk

When: August 28, 1:45 AM CST to 3:30 PM CST
Where: Black Hawk County, 1.68 mi WSW of North Cedar
Reported by: Social Media
Coordinates: 42.540, -92.480

Public reported heavy rainfall of 3.60 inches.

Heavy Rain, Black Hawk

When: August 28, 2:00 AM CST to 4:00 PM CST
Where: Black Hawk County, 1.02 mi E of Waterloo
Reported by: ASOS
Coordinates: 42.500, -92.330

Waterloo ASOS station reported heavy rainfall of 3.37 inches for an event total so far.

Heavy Rain, Black Hawk

When: August 28, 2:00 AM CST to 4:20 PM CST
Where: Black Hawk County, 1.47 mi SSW of Evansdale
Reported by: Social Media
Coordinates: 42.450, -92.290

Public reported heavy rainfall of 2.60 inches event total.

Heavy Rain, Black Hawk

When: August 28, 2:00 AM CST to 5:16 PM CST
Where: Black Hawk County, 1.02 mi E of Waterloo
Reported by: Broadcast Media
Coordinates: 42.500, -92.330

KWWL measured heavy rainfall of 3.10 inches event total at their studio.

Heavy Rain, Hamilton

When: August 28, 4:00 AM CST to 1:35 PM CST
Where: Hamilton County, 0.69 mi S of Ellsworth
Reported by: Mesonet
Coordinates: 42.310, -93.580

City of Ames alert station reported heavy rainfall of 5.00 inches since 5am.

Heavy Rain, Boone

When: August 28, 4:00 AM CST to 1:35 PM CST
Where: Boone County, 2.05 mi E of Ridgeport
Reported by: Mesonet
Coordinates: 42.180, -93.880

City of Ames alert station reported heavy rainfall of 5.60 inches since 5am.

Heavy Rain, Franklin

When: August 28, 7:27 AM CST to August 29, 7:27 AM CST
Where: Franklin County, 0.69 mi N of Oakland
Reported by: Social Media
Coordinates: 42.590, -93.430

Public reported 4 inches of rain near Popejoy over the last 24 hours.

Heavy Rain, Hardin

When: August 28, 7:52 AM CST to August 29, 7:52 AM CST
Where: Hardin County, Radcliffe
Reported by: Social Media
Coordinates: 42.320, -93.430

Public reported heavy rainfall of 8.50 inches of rain over the last 24 hours in Radcliffe.

Heavy Rain, Butler

When: August 28, 7:59 AM CST to August 29, 7:59 AM CST
Where: Butler County, New Hartford
Reported by: Public
Coordinates: 42.570, -92.620

Public report of heavy rainfall of 3.33 inches of rain during the past 24 hours in New Hartford.

Heavy Rain, Black Hawk

When: August 28, 8:00 AM CST to August 29, 8:00 AM CST
Where: Black Hawk County, 1.68 mi ENE of Castle Hill
Reported by: CoCoRaHS
Coordinates: 42.530, -92.370

CoCoRaHS report of heavy rainfall of 4.02 inches over the last 24 hours.

Heavy Rain, Hardin

When: August 28, 8:10 AM CST to August 29, 8:10 AM CST
Where: Hardin County, 0.69 mi S of Eldora
Reported by: Social Media
Coordinates: 42.360, -93.100

Public reported heavy rainfall of 6.75 inches of rain in Eldora over the last 24 hours.

Heavy Rain, Butler

When: August 28, 9:18 AM CST to August 29, 9:18 AM CST
Where: Butler County, Parkersburg
Reported by: COOP Observer
Coordinates: 42.570, -92.780

Coop observer reported heavy rainfall of 3.32 inches over the last 24 hours in Parkersburg.

Heavy Rain, Boone

When: August 28, 10:00 AM CST to 1:05 PM CST
Where: Boone County, 0.86 mi SW of Boxholm
Reported by: Social Media
Coordinates: 42.170, -94.110

Public reported heavy rainfall of 4.50 inches.

Heavy Rain, Humboldt

When: August 28, 10:00 AM CST to 6:45 PM CST
Where: Humboldt County, Livermore
Reported by: Social Media
Coordinates: 42.870, -94.180

Public reported heavy rainfall of 2.60 inches.

Heavy Rain, Greene

When: August 28, 10:30 AM CST to 3:40 PM CST
Where: Greene County, 0.86 mi SW of Hope
Reported by: Social Media
Coordinates: 42.190, -94.210

Public reported heavy rain fall of 4.10 inches for event total so far, with rain still falling at the time of the report.

Heavy Rain, Story

When: August 28, 11:15 AM CST to 4:30 PM CST
Where: Story County, 0.69 mi N of Ontario
Reported by: Trained Spotter
Coordinates: 42.040, -93.680

Trained spotter reported heavy rainfall of 2.18 inches event total.

Heavy Rain, Hamilton

When: August 28, 11:16 AM CST to August 29, 11:16 AM CST
Where: Hamilton County, 1.68 mi ESE of Webster City Arpt
Reported by: Trained Spotter
Coordinates: 42.420, -93.840

Trained spotter reported heavy rainfall of 5.50 inches over the last 24 hours. Of that rain, about 1.25 inches fell in an 8 minute span.

Flash Flood, Webster

When: August 28, 11:30 AM CST to 5:29 PM CST
Where: Webster County, 0.97 mi W of Dayton to 0.06 mi WSW of Dayton
Cause: Heavy Rain
Property damage: $50,000
Reported by: Law Enforcement
Coordinates: 42.271, -94.089

Webster County Sheriff reported Skillet Creek on the west side of Dayton is flooding onto Highway 175 and affecting two bridges near town. One house near the creek was evacuated due to high water.

Flash Flood, Hamilton

When: August 28, 11:30 AM CST to 5:29 PM CST
Where: Hamilton County, 1.1 mi ENE of Stratford to 1.18 mi SE of Stanhope
Cause: Heavy Rain
Property damage: $50,000
Reported by: Law Enforcement
Coordinates: 42.278, -93.912

Hamilton County Law Enforcement reported road closures due to heavy rain and flooding. Locations include along Highway 175 from Stratford to Stanhope. One retirement home was evacuated due to high water.

Heavy Rain, Hardin

When: August 28, 12:15 PM CST to 3:15 PM CST
Where: Hardin County, 0.69 mi N of Hubbard
Reported by: Trained Spotter
Coordinates: 42.310, -93.300

Trained spotter reported 3 hour heavy rainfall total of 2.50 inches.

Flash Flood, Boone

When: August 28, 12:16 PM CST to 5:29 PM CST
Where: Boone County, 1.45 mi SE of Boxholm to 1.11 mi SE of Ridgeport
Cause: Heavy Rain
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 42.163, -94.084

Emergency Manager reported some water over county roads in northern portions of the county at times.

Flash Flood, Hamilton

When: August 28, 12:41 PM CST to 5:29 PM CST
Where: Hamilton County, 1.88 mi N of Jewell to 2.07 mi SE of Jewell
Cause: Heavy Rain
Property damage: $20,000
Reported by: Law Enforcement
Coordinates: 42.327, -93.646

The County Sheriff reported water over Highway 69 at Jewell.

Flash Flood, Hamilton

When: August 28, 12:41 PM CST to 5:29 PM CST
Where: Hamilton County, 1.08 mi W of Kamrar to 1.33 mi S of Kamrar
Cause: Heavy Rain
Property damage: $20,000
Reported by: Law Enforcement
Coordinates: 42.397, -93.751

The County Sheriff reported water over roadways near Kamrar.

Flash Flood, Hamilton

When: August 28, 1:26 PM CST to 5:29 PM CST
Where: Hamilton County, 2.67 mi W of Randall to 2.86 mi SSE of Stratford
Cause: Heavy Rain
Property damage: $25,000
Reported by: Social Media
Coordinates: 42.234, -93.652

Public reported D65 west of Randall has been topped with water flowing over it in a couple of spots. Water also reported over several other county roads west of Randall.

Flash Flood, Webster

When: August 28, 1:44 PM CST to 5:29 PM CST
Where: Webster County, 0.76 mi W of Dayton to 0.71 mi SSW of Dayton
Cause: Heavy Rain
Property damage: $100,000
Reported by: Social Media
Coordinates: 42.271, -94.085

Public reported major flash flooding ongoing throughout the town of Dayton due to Skillet Creek. Fairground, local golf course, and campground are all inundated with at least 5 feet of flowing water.

Flash Flood, Webster

When: August 28, 2:00 PM CST to 5:29 PM CST
Where: Webster County, 1.55 mi W of Dayton to 1.79 mi E of Harcourt
Cause: Heavy Rain
Property damage: $25,000
Reported by: Social Media
Coordinates: 42.272, -94.100

Public reported floodwaters covering US 169 due to runoff from fields and ditches. Time estimated.

Flash Flood, Hamilton

When: August 28, 2:20 PM CST to 5:29 PM CST
Where: Hamilton County, 2.95 mi ESE of Ellsworth to 3.43 mi SE of Ellsworth
Cause: Heavy Rain
Property damage: $10,000
Reported by: Trained Spotter
Coordinates: 42.298, -93.531

Trained spotter reported floodwaters from Long Dick Creek are 6 inches deep and flowing on 340th street 1/4 mile west of Xircus Ave.

Lightning, Black Hawk

When: August 28, 2:30 PM CST
Where: Black Hawk County, 1.04 mi SSW of Hudson
Property damage: $5,000
Reported by: Trained Spotter
Coordinates: 42.405, -92.454

Lightning struck a tree splitting the tree with large limbs down.

Flash Flood, Grundy

When: August 28, 3:06 PM CST to 7:44 PM CST
Where: Grundy County, 2.07 mi N of Wellsburg to 4.76 mi W of Wellsburg
Cause: Heavy Rain
Property damage: $100,000
Reported by: Law Enforcement
Coordinates: 42.460, -92.920

Law Enforcement reported water over the eastbound on ramp to Highway 20 from T-19 north of Wellsburg. There are also reports of several county roads closed due to flooding.

Flash Flood, Boone

When: August 28, 3:34 PM CST to 5:29 PM CST
Where: Boone County, 0.85 mi W of Boxholm to 0.36 mi SW of Boxholm
Cause: Heavy Rain
Property damage: $5,000
Reported by: Trained Spotter
Coordinates: 42.182, -94.116

Trained spotter reported standing water knee deep in parts of town. Approximately 8 inches of rain measured.

Flash Flood, Boone

When: August 28, 3:35 PM CST to 5:29 PM CST
Where: Boone County, 3.16 mi NNE of Pilot Mound to 1.22 mi NW of Ridgeport
Cause: Heavy Rain
Property damage: $50,000
Reported by: Emergency Manager
Coordinates: 42.210, -93.990

Emergency Manager reported Juniper Ave closed in the 100 block. Box culvert also washed out due to the flash flooding.

Flood, Black Hawk

When: August 28, 4:00 PM CST
Where: Black Hawk County, 1.16 mi NE of Orange to 0.92 mi WSW of Cedar Falls
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 42.441, -92.353

Law Enforcement reported minor street flooding across Cedar Falls and Waterloo due to heavy rain. A few cars are stalled/stranded in low intersections.

Flood, Boone

When: August 28, 6:15 PM CST to August 29, 2:00 PM CST
Where: Boone County, 0.98 mi NNE of Mackey to 1.2 mi NE of Mackey
Cause: Heavy Rain
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 42.183, -93.764

Emergency Manager reported 120th St at V ave closed due to flooding from Squaw Creek.

Flood, Boone

When: August 28, 6:15 PM CST to August 29, 2:00 PM CST
Where: Boone County, 3.87 mi WSW of Rosendale to 3.86 mi SW of Rosendale
Cause: Heavy Rain
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 42.197, -93.839

Emergency Manager reported 110th Ave closed between R ave and S ave due to flooding from Squaw Creek.

Flash Flood, Grundy

When: August 28, 6:31 PM CST to 7:44 PM CST
Where: Grundy County, 2.07 mi N of Wellsburg to 2.47 mi NNW of Wellsburg
Cause: Heavy Rain
Property damage: $10,000
Reported by: Department of Highways
Coordinates: 42.460, -92.920

Highway Department reported eastbound entrance ramp to US 20 at exit 187, County Road T19, closed due to flooding.

Flood, Grundy

When: August 28, 7:36 PM CST to August 29, 7:00 PM CST
Where: Grundy County, 5.78 mi NW of Wellsburg to 2.65 mi SW of Ivester
Cause: Heavy Rain
Property damage: $100,000
Reported by: Law Enforcement
Coordinates: 42.498, -92.985

Local Law Enforcement reported many county roads were closed due to water over the road or the road having been washed out. A bridge was washed out at the 2900 block of East 110th between U and T Avenues.

Flood, Story

When: August 29, 4:56 AM CST to 5:20 PM CST
Where: Story County, 1.29 mi NW of Story City to 2.32 mi SSW of Story City
Cause: Heavy Rain
Property damage: $50,000
Reported by: Emergency Manager
Coordinates: 42.194, -93.616

Story County Emergency Manager reported water over Forest Ave between Broad St and 8th St, and flooding in Story City due to the rising South Skunk River. Flooding and standing water was present across much of northern Story County as well.

Flood, Story

When: August 29, 5:05 AM CST
Where: Story County, 3.04 mi SSW of Gilbert to 3.23 mi SSW of Gilbert
Cause: Heavy Rain
Property damage: $50,000
Reported by: Law Enforcement
Coordinates: 42.080, -93.676

Law Enforcement reported a water rescue near Squaw Creek on W 190th St just west of 510th St in Story County. Car pushed downstream with one person stranded for over 75 minutes on top of vehicle. No injuries reported.

Flood, Story

When: August 29, 7:00 AM CST to August 30, 9:54 PM CST
Where: Story County, 2.07 mi SE of Gilbert to 4.82 mi NNW of Ames
Cause: Heavy Rain
Property damage: $250,000
Reported by: Official NWS Observations
Coordinates: 42.100, -93.620

The South Skunk River at Ames W. Riverside Road crested at 17.10 feet on 29 August 2015 at 5:45 PM CDT.

Flood, Story

When: August 29, 7:23 AM CST to August 31, 3:57 AM CST
Where: Story County, 0.69 mi N of Ames Arpt to 2.66 mi S of Cambridge
Cause: Heavy Rain
Property damage: $250,000
Crop damage: $100,000
Reported by: Official NWS Observations
Coordinates: 42.010, -93.620

The South Skunk River at Ames US 30 crested at 24.29 feet on 30 August 2015 at 3:15 AM CDT.

Flood, Story

When: August 29, 12:35 PM CST to August 30, 12:52 AM CST
Where: Story County, 2.81 mi N of Ontario to 2.81 mi WNW of Ames Arpt
Cause: Heavy Rain
Property damage: $250,000
Reported by: Official NWS Observations
Coordinates: 42.070, -93.690

Squaw Creek at Ames Lincoln Way crested at 10.69 feet on 29 August 2015 at 5:30 PM CDT.

Flood, Marshall

When: August 30, 6:30 AM CST to August 31, 9:58 AM CST
Where: Marshall County, 2.66 mi WSW of Marshalltown to Le Grand
Cause: Heavy Rain
Property damage: $250,000
Crop damage: $100,000
Reported by: Official NWS Observations
Coordinates: 42.040, -92.970

The Iowa River at Marshalltown crested at 19.98 feet on 31 August 2015 at 8:30 PM CDT.

Flood, Dallas

When: August 31, 12:00 AM CST to 11:59 PM CST
Where: Dallas County, 2.14 mi SSW of Adel to 0.69 mi ESE of Ortonville
Cause: Heavy Rain
Property damage: $250,000
Crop damage: $100,000
Reported by: Official NWS Observations
Coordinates: 41.590, -94.030

The North Raccoon River at Perry crested at 16.35 feet on 1 September 2015 at 8:30 AM CDT. Another entry for this event is in the September 2015 report.

What these are

Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.
Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
Lightning: A lightning strike that killed, injured or caused damage.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Iowa in 2015 Every state in 2015 This day in weather history Warnings in Iowa, August 2015

Sources

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: 593235, 593135, 593168, 593204, 593226, 593132, 593154, 593165, 593232, 593134, 593137, 593157, 593182, 593184, 593220, 593147, 593151, 593161, 593175, 593181, 593133, 593144, 593149, 593167, 593197, 593206, 593234, 593183, 593222, 593221, 593236, 593185, 593210, 593217, 593219, 593189, 593202, 593213, 593224, 593158, and more.