Flooding in South Dakota, August 18, 2007

Name: Flooding in South Dakota, August 18, 2007
Start: 2007-08-18T02:00
End: 2007-08-18T10:00
Location: South Dakota

August 18, 2007 · NWS ABR · 3 events in 3 counties and zones

The flooding continued across parts of Corson, Dewey, and Walworth counties into the morning hours from the previous nights heavy rains. Many roads and homes were flooded, especially in Mobridge.

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: None recorded
Crop damage: None recorded
Events: 3

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 ABR wrote it up.

The flooding continued across parts of Corson, Dewey, and Walworth counties into the morning hours from the previous nights heavy rains. Many roads and homes were flooded, especially in Mobridge. See the flash flooding storm data entries for Corson, Dewey, and Walworth counties on August 17th and 18th.

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 Aberdeen, SD wrote its last area forecast discussion before the first event at Aug 18, 1:51 AM MST, 9 minutes earlier.

Area forecast discussion, Aug 18, 1:51 AM MST, 9 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
351 AM CDT SAT AUG 18 2007

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
THE EARLIER STORMS IN WESTERN SOUTH DAKOTA HAVE CONSOLIDATED INTO
AN MCS AS EXPECTED THIS EVENING. AN AREA OF HEAVY RAINFALL EARLIER
TONIGHT IN NORTH CENTRAL SOUTH DAKOTA THAT PROMPTED A FLOOD
WARNING HAS SINCE WEAKENED AS IT MOVED EAST...BUT THUNDERSTORM
REDEVELOPMENT ALONG A LINE FROM SOUTHEAST TO NORTHEAST SOUTH
DAKOTA IS MOVING NORTHEAST EARLY THIS MORNING...REACHING KABR
AROUND 08Z. NO SEVERE WEATHER OF NOTE...MOSTLY RAIN WITH SOME
LOCALLY HEAVY AMOUNTS POSSIBLE.

THIS MCS IS EXPECTED TO MOVE NORTHEASTWARD/EASTWARD INTO MINNESOTA
THROUGHOUT THE MORNING AND EARLY AFTERNOON HOURS. WITH THE
GFS/4KM WRF PERFORMING MUCH BETTER THAN THE NAM ON THIS
SYSTEM IN TERMS OF LOCATION...PREFER TO LEAN TOWARD
THESE...ESPECIALLY THE 4KM WRF AS TIMING IS MUCH MORE ACCURATE
THAN THE GFS/NAM AS WELL. THE GFS/NAM SHOW THE HEAVIEST RAIN
BEFORE 12Z IN OUR WESTERN CWA...YET THE HEAVIEST RAIN HAS ALREADY
MOVED WELL TO THE EAST OF THERE AT 08Z. THUS...MOVED THE RAINFALL
CHANCES OUT OF THE CWA EARLIER THAN BOTH THE GFS AND NAM. THIS MAY
ALLOW TEMPERATURES IN THE NORTHEAST TO RISE A LITTLE MORE THAN
CURRENTLY FORECAST...MIDDLE TO UPPER 60S...AS CLOUDS AND
PRECIPITATION MAY NOT HANG OUT AS LONG...BUT WILL RETAIN THESE
HIGHS FOR NOW. DID GO A BIT HIGHER THAN GUIDANCE ON HIGHS...BUT
EXPECTED CONTINUED CLOUD COVER SHOULD STILL KEEP THEM RELATIVELY
LOW FOR AUGUST.

LATER THIS AFTERNOON/EVENING...A FAIRLY STRONG FRONTAL BOUNDARY
SETS UP TO THE SOUTH NEAR THE SOUTH DAKOTA/NEBRASKA BORDER. A
POCKET OF ENERGY...RELATIVELY SMALL COMPARED TO THE ONE PASSING
THROUGH THE REGION RIGHT NOW...COULD HELP TO FIRE SOME
THUNDERSTORMS NEAR AND NORTH OF THIS BOUNDARY THIS EVENING AND
TONIGHT...AND THUS RETAINED CHANCE POPS IN THE SOUTHEAST CWA WITH
MOSTLY SLIGHT CHANCES ELSEWHERE. A COUPLE MORE RELATIVELY WEAK
WAVES TONIGHT AND SUNDAY NIGHT COULD HELP TO GENERATE A FEW
THUNDERSTORMS AS WELL.

.LONG TERM...MONDAY THROUGH FRIDAY
MEDIUM RANGE MODELS REMAIN IN FAIR AGREEMENT ON THE LONG WAVE
PATTERN...BUT DIFFER ON THE DETAILS. THIS SUMMERS FAIRLY STAGNANT
MID LEVEL PATTERN IS FINALLY STARTING TO SHOW SIGNS OF BECOMING
MUCH MORE PROGRESSIVE...PERHAPS A SIGN OF BOREAL AUTUMN JUST
AROUND THE CORNER? ANYWAY...WAVY FRONTAL BOUNDARY EXPECTED TO
REMAIN IN THE VICINITY OF THE ABR CWA THROUGH WEDNESDAY...AND THUS
ANY ENERGY COMING THROUGH THE UPPER FLOW COULD KICK OFF SOME
ACTIVITY...ESPECIALLY OVER EASTERN CWA. THE ONLY REAL SPOILER TO
THUNDERSTORM ACTIVITY/COVERAGE COULD BE POSSIBLE CAPPING WITH MID
LEVEL TEMPS HANGING OUT IN THE +10 TO +12C RANGE AT H700 MONDAY
AND TUESDAY. ALL THAT SAID...MADE ONLY FINE TUNING CHANGES TO THE
WX AND POP GRIDS. TEMPERATURES ALSO LOOKED OKAY AND ONLY MADE A
FEW TWEAKS HERE AND THERE.

&&

.AVIATION...
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS EASTERN
SOUTH DAKOTA THROUGH THE MORNING HOURS. THIS MEANS THAT WIDESPREAD
IFR VSBYS AND CIGS ARE EXPECTED AT KPIR/KATY/KABR THROUGH NOON.
AROUND KMBG EXPECT PATCHES OF CLOUDS BLO 1K FEET THROUGH THE
MORNING WITH ONLY A FEW LINGERING SHOWERS.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

SHORT TERM...ECKSTEIN
LONG TERM...TDK
AVIATION...TDK

Hazardous weather outlook, Aug 17, 3:36 PM MST, 10 hours 24 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
536 PM CDT FRI AUG 17 2007

MNZ039-046-SDZ006>008-011-019>023-182245-
TRAVERSE-BIG STONE-BROWN-MARSHALL-ROBERTS-DAY-CLARK-CODINGTON-
GRANT-HAMLIN-DEUEL-
536 PM CDT FRI AUG 17 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL
MINNESOTA AND NORTHEAST SOUTH DAKOTA.

.DAY ONE...TONIGHT

CHANCES OF THUNDERSTORMS WILL BE ON THE INCREASE LATE THIS
EVENING...AND BECOMING LIKELY AFTER MIDNIGHT TONIGHT. THESE
STORMS ARE NOT EXPECTED TO BE SEVERE AT THIS TIME...HOWEVER...HEAVY
RAINFALL AND DANGEROUS LIGHTNING WILL BE POSSIBLE WITH THESE
THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS SHOULD BE ONGOING ON SATURDAY MORNING ACROSS THE
AREA...WITH CHANCES THROUGH THE EARLY AFTERNOON. THUNDERSTORMS ARE
AGAIN POSSIBLE MONDAY THROUGH WEDNESDAY...BUT IT IS TOO EARLY TO
DETERMINE MORE DEFINITE TIME PERIODS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THIS EVENING...ALTHOUGH ANY
REPORTS OF LARGE HAIL OBSERVED OVERNIGHT WOULD BE GREATLY
APPRECIATED.

SDZ003>005-009-010-015>018-034>037-051-182245-
CORSON-CAMPBELL-MCPHERSON-WALWORTH-EDMUNDS-DEWEY-POTTER-FAULK-
SPINK-SULLY-HUGHES-HYDE-HAND-BUFFALO-
536 PM CDT FRI AUG 17 2007 /436 PM MDT FRI AUG 17 2007/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL SOUTH
DAKOTA...NORTH CENTRAL SOUTH DAKOTA AND NORTHEAST SOUTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

CHANCES OF THUNDERSTORMS WILL INCREASE THIS EVENING...BECOMING
LIKELY BY LATE THIS EVENING INTO TONIGHT. THERE IS A SLIGHT CHANCE
THAT SOME OF THESE STORMS COULD BECOME SEVERE EARLY THIS EVENING
INTO TONIGHT WITH LARGE HAIL AND DAMAGING WINDS THE PRIMARY
HAZARDS. HEAVY RAINFALL WILL ALSO BE POSSIBLE WITH THESE
THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE IS A CHANCE OF ONGOING THUNDERSTORMS SATURDAY MORNING.
THUNDERSTORMS ARE AGAIN POSSIBLE MONDAY THROUGH WEDNESDAY...BUT IT
IS TOO EARLY TO DETERMINE MORE DEFINITE TIME PERIODS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY THIS EVENING THROUGH TONIGHT.

SDZ033-045-048-182245-
STANLEY-JONES-LYMAN-
536 PM CDT FRI AUG 17 2007 /436 PM MDT FRI AUG 17 2007/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL SOUTH
DAKOTA.

.DAY ONE...TODAY AND TONIGHT

A TORNADO WATCH IS IN EFFECT UNTIL 1 AM CDT...12 AM MDT. CHANCES
OF THUNDERSTORMS WILL INCREASE THIS EVENING INTO TONIGHT. SOME OF
THESE STORMS COULD BECOME SEVERE THIS EVENING INTO TONIGHT WITH
LARGE HAIL...DAMAGING WINDS AND POSSIBLY A TORNADO OR TWO BEING
THE PRIMARY HAZARDS. HEAVY RAINFALL WILL ALSO BE POSSIBLE WITH
THESE THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS ARE POSSIBLE MONDAY THROUGH WEDNESDAY...BUT IT IS
TOO EARLY TO DETERMINE MORE DEFINITE TIME PERIODS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS BEING REQUESTED FOR THIS EVENING THROUGH
TONIGHT.

DORN

In the hours before

Local storm report, Aug 17, 10:37 PM MST, 3 hours 23 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
1237 AM CDT SAT AUG 18 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1230 AM     HEAVY RAIN       MOBRIDGE                45.54N 100.44W
08/18/2007  E0.00 INCH       WALWORTH           SD   PUBLIC

            REPORTS OF BASEMENT FLOODING AND BASEMENT WALL COLLAPSES

&&

TDK

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 flood. Local standard time, as filed.

Flood, Corson

When: August 18, 2:00 AM MST to 8:00 AM MST
Where: Corson County, 0.69 mi N of Little Eagle
Cause: Heavy Rain
Reported by: Public
Coordinates: 45.680, -100.820

Flood, Dewey

When: August 18, 2:00 AM MST to 8:00 AM MST
Where: Dewey County, 1.38 mi N of Moreau
Cause: Heavy Rain
Reported by: Public
Coordinates: 45.390, -100.450

Flood, Walworth

When: August 18, 3:00 AM CST to 10:00 AM CST
Where: Walworth County, 0.84 mi NW of Mobridge
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 45.540, -100.440

What these are

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 South Dakota in 2007 Every state in 2007 This day in weather history Warnings in South Dakota, August 2007

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: 58920, 58928, 58932.