Alert archive / South Dakota / Flash Flood Warnings
Flash Flood Warnings in South Dakota, 2016
33 flash flood warnings in 2016. 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 2016. Tap one for its archive.
- Flash Flood Warnings
- 33
- Busiest month
- July7 flash flood warnings
- Busiest day
- September 15, 20164 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.
17 of 33 flash flood warnings covering South Dakota in 2016 had a flash flood report inside them; 27 of 30 flash flood reports fell inside a warning, on average 66 minutes after it went out.
South Dakota, 2016
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Flash flood warnings | 33 | 17 | 48% | 30 | 90% | 66 min |
Each office's whole area, 2016
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sioux Falls, SD: flash flood warnings | 34 | 13 | 62% | 23 | 100% | 64 min |
| NWS Aberdeen, SD: flash flood warnings | 7 | 3 | 57% | 7 | 57% | 36 min |
| NWS Rapid City, SD: flash flood warnings | 6 | 5 | 17% | 7 | 100% | 88 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 20, 8:00 PM CDT | Flash Flood Warning | UNR | Custer, Pennington | 5 hr |
| May 22, 8:13 PM CDT | Flash Flood Warning | UNR | Todd, Tripp | 3 hr |
| May 22, 10:45 PM CDT | Flash Flood Warning | FSD | Aurora, Brule, Charles Mix, Gregory | 6 hr |
| May 23, 5:58 PM CDT | Flash Flood Warning | FSD | Union | 4 hr |
| May 30, 12:28 AM CDT | Flash Flood Warning | FSD | Charles Mix | 3 hr |
| Jun 14, 12:27 PM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Union | 3 hr |
| Jun 17, 6:49 PM CDT | Flash Flood Warning | FSD | Brookings | 3 hr |
| Jun 17, 7:17 PM CDT | Flash Flood Warning | FSD | Lake | 3 hr |
| Jun 17, 8:26 PM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 3 hr |
| Jun 17, 8:52 PM CDT | Flash Flood Warning | FSD | Hutchinson, McCook | 3 hr |
| Jun 30, 12:50 AM CDT | Flash Flood Warning | FSD | Union | 3 hr |
| Jul 15, 4:47 PM CDT | Flash Flood Warning | UNR | Pennington | 118 min |
| Jul 16, 11:35 PM CDT | Flash Flood Warning | FSD | Brookings | 6 hr |
| Jul 22, 6:59 PM CDT | Flash Flood Warning | ABR | Corson, Dewey | 6 hr |
| Jul 22, 10:51 PM CDT | Flash Flood Warning | UNR | Haakon | 6 hr |
| Jul 26, 2:11 PM CDT | Flash Flood Warning | FSD | Beadle | 3 hr |
| Jul 26, 5:12 PM CDT | Flash Flood Warning | ABR | Buffalo, Lyman | 3 hr |
| Jul 26, 7:00 PM CDT | Flash Flood Warning | UNR | Mellette, Todd | 6 hr |
| Jul 31, 7:28 PM CDT | Flash Flood Warning | UNR | Harding | 6 hr |
| Aug 10, 5:37 PM CDT | Flash Flood Warning | ABR | Day | 6 hr |
| Aug 10, 8:30 PM CDT | Flash Flood Warning | ABR | Dewey, Potter | 6 hr |
| Aug 11, 11:28 PM CDT | Flash Flood Warning | ABR | Codington, Hamlin | 3 hr |
| Aug 12, 12:25 AM CDT | Flash Flood Warning | ABR | Deuel, Hamlin | 3 hr |
| Aug 18, 8:16 PM CDT | Flash Flood Warning | FSD | Miner | 3 hr |
| Aug 18, 10:25 PM CDT | Flash Flood Warning | FSD | Sanborn | 3 hr |
| Sep 6, 2:20 AM CDT | Flash Flood Warning | FSD | Aurora, Brule, Charles Mix, Gregory | 3 hr |
| Sep 6, 2:57 AM CDT | Flash Flood Warning | FSD | Lake, Miner, Sanborn | 3 hr |
| Sep 7, 1:45 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Union, Yankton | 4 hr |
| Sep 15, 11:34 AM CDT | Flash Flood Warning | FSD | Bon Homme, Clay, Hutchinson, Lincoln, McCook, Minnehaha and 3 more | 3 hr |
| Sep 15, 1:40 PM CDT | Flash Flood Warning | FSD | Lincoln, Minnehaha | 3 hr |
| Sep 15, 2:11 PM CDT | Flash Flood Warning | FSD | Bon Homme, Clay, Hutchinson, Lincoln, McCook, Minnehaha and 3 more | 3 hr |
| Sep 15, 4:37 PM CDT | Flash Flood Warning | FSD | Lincoln | 3 hr |
| Dec 25, 6:13 PM CST | Flash Flood Warning | ABR | Brown | 6 hr |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Lincoln County7
- Union County6
- Clay County4
- Minnehaha County4
- Charles Mix County3
- Hutchinson County3
- McCook County3
- Yankton County3
- Pennington County2
- Todd County2
- Aurora County2
- Brule County2
- Gregory County2
- Brookings County2
- Lake County2
- Dewey County2
- Hamlin County2
- Miner County2
- Sanborn County2
- Bon Homme County2
- Turner County2
- Custer County1
- Tripp County1
- Corson County1
- Haakon County1
- Beadle County1
- Buffalo County1
- Lyman County1
- Mellette County1
- Harding County1
- Day County1
- Potter County1
- Codington County1
- Deuel County1
- Brown County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20152017
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.