Alert archive / South Dakota / Flash Flood Warnings
Flash Flood Warnings in South Dakota, 2018
46 flash flood warnings in 2018. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of flash flood warnings reaches back to 1986.
Flash Flood Warnings by county
Each county as a circle sized by its count in 2018. Tap one for its archive.
- Flash Flood Warnings
- 46
- Busiest month
- July19 flash flood warnings
- Busiest day
- September 20, 20186 flash flood warnings
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
35 of 46 flash flood warnings covering South Dakota in 2018 had a flash flood report inside them; 39 of 55 flash flood reports fell inside a warning, on average 91 minutes after it went out.
South Dakota, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Flash flood warnings | 46 | 35 | 24% | 55 | 71% | 91 min |
Each office's whole area, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sioux Falls, SD: flash flood warnings | 43 | 31 | 28% | 66 | 82% | 104 min |
| NWS Aberdeen, SD: flash flood warnings | 12 | 11 | 8% | 16 | 69% | 142 min |
| NWS Rapid City, SD: flash flood warnings | 13 | 8 | 38% | 16 | 69% | 42 min |
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.
The alerts
Every alert, in the order issued. Times are local, Central Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 3:52 PM CDT | Flash Flood Warning | ABR | McPherson | 4 hr |
| May 17, 4:06 PM CDT | Flash Flood Warning | UNR | Custer, Fall River | 5 hr |
| May 17, 5:29 PM CDT | Flash Flood Warning | ABR | McPherson | 4 hr |
| May 17, 8:56 PM CDT | Flash Flood Warning | UNR | Custer, Fall River | 102 min |
| May 18, 7:46 PM CDT | Flash Flood Warning | UNR | Pennington | 2 hr |
| May 22, 4:43 PM CDT | Flash Flood Warning | UNR | Lawrence, Pennington | 3 hr |
| Jun 7, 3:03 AM CDT | Flash Flood Warning | FSD | Charles Mix, Gregory | 3 hr |
| Jun 8, 6:08 PM CDT | Flash Flood Warning | UNR | Jackson | 3 hr |
| Jun 16, 9:19 PM CDT | Flash Flood Warning | ABR | Jones | 6 hr |
| Jun 22, 2:37 PM CDT | Flash Flood Warning | UNR | Pennington | 93 min |
| Jun 22, 6:02 PM CDT | Flash Flood Warning | UNR | Jackson | 3 hr |
| Jun 24, 7:53 PM CDT | Flash Flood Warning | FSD | Clay, Union | 3 hr |
| Jun 24, 9:05 PM CDT | Flash Flood Warning | FSD | Union | 3 hr |
| Jun 24, 10:41 PM CDT | Flash Flood Warning | FSD | Union | 4 hr |
| Jun 24, 11:13 PM CDT | Flash Flood Warning | FSD | Union | 4 hr |
| Jun 27, 6:50 AM CDT | Flash Flood Warning | ABR | Hughes, Stanley | 3 hr |
| Jun 27, 10:03 AM CDT | Flash Flood Warning | ABR | Lyman | 3 hr |
| Jul 2, 10:18 PM CDT | Flash Flood Warning | ABR | Hand, Spink | 8 hr |
| Jul 2, 11:35 PM CDT | Flash Flood Warning | ABR | Hand, Spink | 8 hr |
| Jul 3, 1:56 AM CDT | Flash Flood Warning | ABR | Faulk, Hand, Hyde | 6 hr |
| Jul 3, 8:21 PM CDT | Flash Flood Warning | ABR | Faulk, Hand | 6 hr |
| Jul 4, 1:51 AM CDT | Flash Flood Warning | ABR | Campbell, Corson | 6 hr |
| Jul 12, 6:31 PM CDT | Flash Flood Warning | FSD | Gregory | 2 hr |
| Jul 12, 7:23 PM CDT | Flash Flood Warning | FSD | Aurora, Charles Mix, Davison, Douglas, Gregory, Hanson and 2 more | 3 hr |
| Jul 12, 9:07 PM CDT | Flash Flood Warning | FSD | Gregory | 3 hr |
| Jul 12, 9:46 PM CDT | Flash Flood Warning | FSD | Aurora, Charles Mix, Davison, Douglas, Gregory, Hanson and 2 more | 6 hr |
| Jul 17, 4:43 PM CDT | Flash Flood Warning | UNR | Custer, Pennington | 3 hr |
| Jul 17, 7:50 PM CDT | Flash Flood Warning | UNR | Butte, Lawrence | 3 hr |
| Jul 18, 1:38 PM CDT | Flash Flood Warning | FSD | Brule | 4 hr |
| Jul 19, 3:02 AM CDT | Flash Flood Warning | FSD | Brookings | 6 hr |
| Jul 19, 5:46 AM CDT | Flash Flood Warning | FSD | Brookings | 3 hr |
| Jul 21, 8:23 PM CDT | Flash Flood Warning | UNR | Meade, Pennington | 3 hr |
| Jul 21, 8:59 PM CDT | Flash Flood Warning | UNR | Pennington | 3 hr |
| Jul 22, 1:02 AM CDT | Flash Flood Warning | ABR | Corson, Dewey | 6 hr |
| Jul 22, 2:51 AM CDT | Flash Flood Warning | ABR | Dewey, Potter | 6 hr |
| Jul 25, 1:54 AM CDT | Flash Flood Warning | FSD | Brule, Charles Mix, Gregory | 5 hr |
| Aug 5, 2:00 AM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 3 hr |
| Aug 14, 12:44 PM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 2 hr |
| Aug 15, 5:56 PM CDT | Flash Flood Warning | FSD | Kingsbury | 2 hr |
| Aug 19, 4:45 PM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 90 min |
| Sep 20, 3:36 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Turner | 6 hr |
| Sep 20, 4:35 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Union | 5 hr |
| Sep 20, 4:51 AM CDT | Flash Flood Warning | FSD | Hutchinson, Turner, Yankton | 5 hr |
| Sep 20, 9:29 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Turner | 3 hr |
| Sep 20, 9:30 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Union | 3 hr |
| Sep 20, 9:41 AM CDT | Flash Flood Warning | FSD | Hutchinson, Turner, Yankton | 3 hr |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Lincoln County7
- Pennington County6
- Gregory County6
- Union County6
- Clay County5
- Charles Mix County4
- Hand County4
- Hutchinson County4
- Turner County4
- Custer County3
- Minnehaha County3
- McPherson County2
- Fall River County2
- Lawrence County2
- Jackson County2
- Spink County2
- Faulk County2
- Corson County2
- Aurora County2
- Davison County2
- Douglas County2
- Hanson County2
- McCook County2
- Brule County2
- Brookings County2
- Dewey County2
- Yankton County2
- Jones County1
- Hughes County1
- Stanley County1
- Lyman County1
- Hyde County1
- Campbell County1
- Butte County1
- Meade County1
- Potter County1
- Kingsbury County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20172019
Sources
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.