South Dakota, 2020

Flash Flooding and Flooding in South Dakota, July 24 to 26, 2020

July 24 to 26, 2020 · NWS ABR · 6 events in 3 counties and zones

Storms tracked across north central and northeast South Dakota during the evening hours of July 24th and into July 25th. Developing in a very moisture rich atmosphere, the storms were able to produce very heavy rain in a short amount of time, especially over parts of northeastern McPherson County, northern Brown County and far northwestern Marshall County.

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
6

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.

Storms tracked across north central and northeast South Dakota during the evening hours of July 24th and into July 25th. Developing in a very moisture rich atmosphere, the storms were able to produce very heavy rain in a short amount of time, especially over parts of northeastern McPherson County, northern Brown County and far northwestern Marshall County. Rainfall amounts ranged from 4 to 8 inches, while localized amounts approached a foot. The heavy rain led to significant overland flooding as well as flooding on Elm Lake and subsequent flooding downstream along the Elm River. Many roads were underwater or completely washed out. There were reports of boats and docks submerged with others freely floating on Elm Lake. The river gauge on the Elm River, just below Elm Lake, (ERFS2) reached a record stage of 19.56 feet in the afternoon of July 25th. The Elm River at Westport (WESS2) crested at a major flood stage of 20.45 feet in the early morning of the 27th.

Some of the heaviest rainfall amounts include, 4.94 inches 13 miles northwest of Britton; 6.75 inches 4 miles northwest of Elm Lake, 6.86 inches 2 miles east northeast of Spring Creek Colony; 7.04 inches 9 miles east of Spring Creek Colony; 7.80 inches 10 miles northwest Frederick; and 11.92 inches 11.5 miles west-northwest of Frederick.

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.

In the hours before

Local storm report, Jul 24, 7:04 PM CST, 2 hours 56 minutes before
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Local storm report, Jul 24, 7:10 PM CST, 2 hours 50 minutes before
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Local storm report, Jul 24, 9:26 PM CST, 34 minutes before
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Local storm report, Jul 24, 9:37 PM CST, 23 minutes before
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The radar

The Aberdeen radar (KABR), 68 km away, was scanning. The volume nearest the first event began at 03:56 UTC.

Open the radar archive at this moment

Event by event

3 flood, 2 flash flood, 1 thunderstorm wind. Local standard time, as filed.

Flood, McPherson

When
July 24, 10:00 PM CST to July 26, 10:00 AM CST
Where
McPherson County, 7.74 mi S of Langlake to 4.39 mi NNE of Wetonka
Cause
Heavy Rain
Reported by
Emergency Manager
Coordinates
45.740, -99.190

Flood, Brown

When
July 24, 10:00 PM CST to July 26, 10:00 AM CST
Where
Brown County, 9.71 mi W of Winship to 8.74 mi W of Barnard
Cause
Heavy Rain
Reported by
Emergency Manager
Coordinates
45.940, -98.720

Thunderstorm Wind, Brown

When
July 24, 10:54 PM CST
Where
Brown County, 8.2 mi W of Winship
Measured
51 kt (59 mph) measured gust
Reported by
Mesonet
Coordinates
45.910, -98.690

Flood, Marshall

When
July 25, 12:00 AM CST to July 26, 10:00 AM CST
Where
Marshall County, 8.17 mi W of Newark to 0.96 mi WNW of Amherst
Cause
Heavy Rain
Reported by
Emergency Manager
Coordinates
45.930, -97.970

Flash Flood, McPherson

When
July 25, 2:10 AM CST to 5:10 AM CST
Where
McPherson County, 5.05 mi SE of Spring Creek Colony to 3.42 mi SSE of Spring Creek Colony
Cause
Heavy Rain
Reported by
Emergency Manager
Coordinates
45.840, -98.770

Many county roads were underwater in northeast Mcpherson county due to flash flooding from very heavy rainfall.

Flash Flood, Brown

When
July 25, 2:30 AM CST to 5:30 AM CST
Where
Brown County, 8.69 mi W of Frederick to 7.63 mi W of Frederick
Cause
Heavy Rain
Reported by
Emergency Manager
Coordinates
45.840, -98.700

Many roads were underwater and damaged from flash flooding in northwest Brown County.

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.
Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
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.

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

The same day elsewhere

More

Every storm in South Dakota in 2020Every state in 2020This day in weather historyWarnings in South Dakota, July 2020

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 2026-10-01. Each event’s entry at NCEI: 910253, 910254, 910257, 910255, 910251, 910252.