Alert archive / South Dakota / Flash Flood Warnings
Flash Flood Warnings in South Dakota, 2019
48 flash flood warnings in 2019. 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 2019. Tap one for its archive.
- Flash Flood Warnings
- 48
- Busiest month
- August13 flash flood warnings
- Busiest day
- September 11, 20198 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.
28 of 48 flash flood warnings covering South Dakota in 2019 had a flash flood report inside them; 38 of 46 flash flood reports fell inside a warning, on average 84 minutes after it went out.
South Dakota, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Flash flood warnings | 48 | 28 | 42% | 46 | 83% | 84 min |
Each office's whole area, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Aberdeen, SD: flash flood warnings | 3 | 1 | 67% | 2 | 100% | 8 min |
| NWS Sioux Falls, SD: flash flood warnings | 32 | 19 | 41% | 26 | 81% | 73 min |
| NWS Rapid City, SD: flash flood warnings | 24 | 12 | 50% | 28 | 86% | 94 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 |
|---|---|---|---|---|
| Mar 13, 9:43 PM CDT | Flash Flood Warning | FSD | Bon Homme, Clay, Yankton | 6 hr |
| Mar 26, 10:27 AM CDT | Flash Flood Warning | UNR | Haakon, Jackson, Pennington | 5 hr |
| May 17, 9:01 PM CDT | Flash Flood Warning | FSD | Brookings | 94 min |
| May 26, 10:09 PM CDT | Flash Flood Warning | UNR | Haakon, Meade, Ziebach | 6 hr |
| May 31, 5:21 PM CDT | Flash Flood Warning | UNR | Pennington | 5 hr |
| May 31, 8:07 PM CDT | Flash Flood Warning | UNR | Meade | 2 hr |
| May 31, 8:39 PM CDT | Flash Flood Warning | ABR | Hughes, Stanley | 3 hr |
| Jun 4, 4:35 PM CDT | Flash Flood Warning | ABR | Deuel | 5 hr |
| Jun 27, 8:18 AM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha, Turner | 117 min |
| Jun 27, 9:14 AM CDT | Flash Flood Warning | FSD | Lincoln | 3 hr |
| Jun 30, 11:31 PM CDT | Flash Flood Warning | ABR | Hughes, Stanley, Sully | 6 hr |
| Jul 1, 9:28 PM CDT | Flash Flood Warning | FSD | Union | 3 hr |
| Jul 3, 8:08 AM CDT | Flash Flood Warning | FSD | Union | 3 hr |
| Jul 3, 3:45 PM CDT | Flash Flood Warning | FSD | Beadle, Jerauld, Sanborn | 2 hr |
| Jul 3, 6:48 PM CDT | Flash Flood Warning | UNR | Lawrence, Pennington | 5 hr |
| Jul 4, 9:31 PM CDT | Flash Flood Warning | UNR | Lawrence, Meade | 6 hr |
| Jul 5, 5:38 PM CDT | Flash Flood Warning | UNR | Lawrence, Meade | 4 hr |
| Jul 14, 5:49 PM CDT | Flash Flood Warning | UNR | Pennington | 3 hr |
| Jul 17, 7:06 AM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 4 hr |
| Jul 17, 7:19 AM CDT | Flash Flood Warning | FSD | Union | 116 min |
| Jul 21, 5:35 AM CDT | Flash Flood Warning | UNR | Butte | 3 hr |
| Jul 23, 6:12 PM CDT | Flash Flood Warning | UNR | Pennington | 6 hr |
| Aug 1, 11:41 PM CDT | Flash Flood Warning | UNR | Jackson, Oglala Lakota, Pennington | 6 hr |
| Aug 2, 3:43 PM CDT | Flash Flood Warning | UNR | Custer | 3 hr |
| Aug 5, 4:30 PM CDT | Flash Flood Warning | UNR | Custer | 3 hr |
| Aug 6, 9:34 PM CDT | Flash Flood Warning | FSD | Brule, Charles Mix | 3 hr |
| Aug 9, 7:52 PM CDT | Flash Flood Warning | FSD | Gregory | 6 hr |
| Aug 9, 9:14 PM CDT | Flash Flood Warning | UNR | Tripp | 6 hr |
| Aug 10, 7:27 PM CDT | Flash Flood Warning | UNR | Custer, Pennington | 93 min |
| Aug 11, 5:22 PM CDT | Flash Flood Warning | UNR | Oglala Lakota | 4 hr |
| Aug 11, 5:52 PM CDT | Flash Flood Warning | UNR | Fall River | 3 hr |
| Aug 11, 6:15 PM CDT | Flash Flood Warning | UNR | Fall River | 3 hr |
| Aug 11, 7:09 PM CDT | Flash Flood Warning | UNR | Oglala Lakota | 3 hr |
| Aug 11, 8:20 PM CDT | Flash Flood Warning | UNR | Bennett, Jackson, Oglala Lakota | 3 hr |
| Aug 11, 8:59 PM CDT | Flash Flood Warning | UNR | Oglala Lakota | 110 min |
| Sep 2, 12:33 AM CDT | Flash Flood Warning | UNR | Haakon, Ziebach | 6 hr |
| Sep 10, 9:29 PM CDT | Flash Flood Warning | FSD | Bon Homme, Charles Mix, Davison, Douglas, Hanson, Hutchinson | 6 hr |
| Sep 10, 10:22 PM CDT | Flash Flood Warning | FSD | Hanson, Hutchinson, McCook, Turner | 5 hr |
| Sep 10, 11:26 PM CDT | Flash Flood Warning | FSD | Lake, Lincoln, McCook, Miner, Minnehaha, Moody and 1 more | 3 hr |
| Sep 11, 12:24 AM CDT | Flash Flood Warning | FSD | Clay, Hutchinson, Lincoln, Turner, Union, Yankton | 6 hr |
| Sep 11, 12:24 AM CDT | Flash Flood Warning | FSD | Brookings, Kingsbury, Lake, Moody | 6 hr |
| Sep 11, 1:03 AM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 6 hr |
| Sep 11, 2:17 AM CDT | Flash Flood Warning | FSD | Lake, Lincoln, McCook, Miner, Minnehaha, Moody and 1 more | 4 hr |
| Sep 11, 3:14 AM CDT | Flash Flood Warning | FSD | Union | 4 hr |
| Sep 11, 9:01 PM CDT | Flash Flood Warning | FSD | Aurora, Brule, Charles Mix, Davison, Douglas, Gregory and 1 more | 4 hr |
| Sep 11, 10:12 PM CDT | Flash Flood Warning | FSD | Moody | 4 hr |
| Sep 11, 10:47 PM CDT | Flash Flood Warning | FSD | Hanson, Lake, McCook, Miner, Minnehaha | 3 hr |
| Sep 12, 2:38 AM CDT | Flash Flood Warning | FSD | Davison | 4 hr |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Pennington County7
- Lincoln County7
- Minnehaha County6
- Turner County5
- Union County5
- Oglala Lakota County5
- Meade County4
- Hanson County4
- McCook County4
- Lake County4
- Moody County4
- Haakon County3
- Jackson County3
- Lawrence County3
- Custer County3
- Charles Mix County3
- Davison County3
- Hutchinson County3
- Miner County3
- Bon Homme County2
- Clay County2
- Yankton County2
- Brookings County2
- Ziebach County2
- Hughes County2
- Stanley County2
- Brule County2
- Gregory County2
- Fall River County2
- Douglas County2
- Deuel County1
- Sully County1
- Beadle County1
- Jerauld County1
- Sanborn County1
- Butte County1
- Tripp County1
- Bennett County1
- Kingsbury County1
- Aurora County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20182020
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.