Flash Flood Warnings in South Dakota, 2020

By month

15 of 24 flash flood warnings covering South Dakota in 2020 had a flash flood report inside them; 20 of 24 flash flood reports fell inside a warning, on average 88 minutes after it went out.

South Dakota, 2020

Each office's whole area, 2020

An office's figures cover every county it serves, including across state lines.

Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.

• Butte County3
• Meade County3
• Haakon County3
• Charles Mix County3
• Douglas County3
• Lawrence County2
• Jackson County2
• Pennington County2
• Aurora County2
• Davison County2
• Beadle County2
• Kingsbury County2
• Hutchinson County2
• Dewey County2
• Union County2
• Ziebach County1
• Brule County1
• Bon Homme County1
• Sully County1
• Brown County1
• McPherson County1
• Clay County1
• Hughes County1
• Stanley County1
• Oglala Lakota County1
• Mellette County1

1. May 24, 20203flash flood warnings
2. June 26, 20203flash flood warnings
3. July 29, 20203flash flood warnings
4. May 23, 20202flash flood warnings
5. June 9, 20202flash flood warnings
6. July 7, 20202flash flood warnings
7. July 22, 20202flash flood warnings
8. May 16, 20201flash flood warnings
9. July 6, 20201flash flood warnings
10. July 10, 20201flash flood warnings
11. July 25, 20201flash flood warnings
12. July 28, 20201flash flood warnings

Alerts in force nowTornadoes on recordThe radar archive20192021

National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.