Alert archive / South Dakota / Union County
Weather alerts in Union County, South Dakota, 2019
132 weather alerts in 2019, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Union County and its neighbors
Each county as a circle sized by its count in 2019. Tap one for its archive.
- Alerts
- 132
- Warnings
- 54
- Watches
- 19
- Advisories
- 44
- Busiest month
- July24 alerts
- Busiest day
- July 17, 20198 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
0 of 1 tornado warnings covering Union County in 2019 had a tornado report inside them.
Union County, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 1 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 5 | 4 | 20% | 2 | 50% | 23 min |
| Flash flood warnings | 5 | 2 | 60% | 0 |
Each office's whole area, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sioux Falls, SD: tornado warnings | 37 | 10 | 73% | 26 | 50% | 7 min |
| NWS Sioux Falls, SD: severe thunderstorm warnings | 172 | 107 | 38% | 251 | 88% | 18 min |
| NWS Sioux Falls, SD: flash flood warnings | 32 | 19 | 41% | 26 | 81% | 73 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 | Lasted |
|---|---|---|---|
| Jan 7, 2:44 PM CST | Wind Advisory | FSD | 30 hr |
| Jan 16, 3:00 PM CST | Winter Weather Advisory | FSD | 57 hr |
| Jan 21, 3:26 AM CST | Winter Weather Advisory | FSD | 35 hr |
| Jan 26, 2:21 PM CST | High Wind Watch | FSD | 13 hr |
| Jan 27, 3:34 AM CST | Wind Chill Watch | FSD | 24 hr |
| Jan 27, 3:48 AM CST | High Wind Warning | FSD | 26 hr |
| Jan 27, 3:48 AM CST | Wind Advisory | FSD | 32 hr |
| Jan 28, 3:34 AM CST | Wind Chill Warning | FSD | 3 days |
| Jan 28, 3:34 AM CST | Wind Chill Advisory | FSD | 35 hr |
| Jan 28, 3:34 AM CST | Wind Chill Advisory | FSD | 3 days |
| Feb 3, 3:43 AM CST | Winter Weather Advisory | FSD | 26 hr |
| Feb 5, 3:25 PM CST | Winter Weather Advisory | FSD | 57 hr |
| Feb 7, 3:19 AM CST | Wind Chill Advisory | FSD | 54 hr |
| Feb 10, 2:54 PM CST | Winter Weather Advisory | FSD | 39 hr |
| Feb 15, 2:55 PM CST | Winter Weather Advisory | FSD | 51 hr |
| Feb 19, 4:07 AM CST | Winter Storm Warning | FSD | 35 hr |
| Feb 21, 3:52 AM CST | Winter Weather Advisory | FSD | 3 days |
| Feb 22, 3:26 PM CST | Blizzard Warning | FSD | 51 hr |
| Mar 2, 3:59 AM CST | Wind Chill Advisory | FSD | 56 hr |
| Mar 6, 3:04 AM CST | Winter Weather Advisory | FSD | 37 hr |
| Mar 8, 3:16 PM CST | Winter Weather Advisory | FSD | 38 hr |
| Mar 11, 3:03 PM CDT | Winter Storm Watch | FSD | 49 hr |
| Mar 11, 3:13 PM CDT | Flood Watch | FSD | 72 hr |
| Mar 12, 3:26 PM CDT | River Flood Watch | FSD | 23 days |
| Mar 12, 3:26 PM CDT | River Flood Watch | FSD | 22 days |
| Mar 12, 5:41 PM CDT | Dense Fog Advisory | FSD | 19 hr |
| Mar 13, 6:58 AM CDT | River Flood Warning | FSD | 21 days |
| Mar 13, 8:34 AM CDT | Areal Flood Warning | FSD | 12 hr |
| Mar 13, 11:04 AM CDT | River Flood Warning | FSD | 90 days |
| Mar 13, 11:04 AM CDT | River Flood Warning | FSD | 94 days |
| Mar 13, 4:03 PM CDT | Winter Weather Advisory | FSD | 27 hr |
| Mar 13, 4:06 PM CDT | Wind Advisory | FSD | 36 hr |
| Mar 13, 8:27 PM CDT | Areal Flood Warning | FSD | 21 hr |
| Mar 13, 10:32 PM CDT | River Flood Warning | FSD | 8 days |
| Mar 14, 6:14 AM CDT | River Flood Warning | FSD | 93 days |
| Mar 14, 5:25 PM CDT | Areal Flood Warning | FSD | 24 hr |
| Mar 14, 9:52 PM CDT | River Flood Warning | FSD | 68 hr |
| Mar 15, 9:46 PM CDT | River Flood Warning | FSD | 21 days |
| Apr 4, 10:24 PM CDT | Dense Fog Advisory | FSD | 12 hr |
| Apr 10, 3:24 PM CDT | Wind Advisory | FSD | 22 hr |
| Apr 11, 2:34 AM CDT | Mesoscale Discussion | SPC | 6 hr |
| Apr 11, 9:06 AM CDT | River Flood Warning | FSD | 21 days |
| May 4, 3:44 AM CDT | Dense Fog Advisory | FSD | 5 hr |
| May 9, 3:38 AM CDT | Frost Advisory | FSD | 28 hr |
| May 20, 2:58 PM CDT | Wind Advisory | FSD | 32 hr |
| May 28, 1:57 PM CDT | River Flood Warning | FSD | 21 days |
| May 29, 10:18 AM CDT | River Flood Warning | FSD | 21 days |
| May 29, 2:42 PM CDT | River Flood Warning | FSD | 21 days |
| May 30, 9:47 AM CDT | River Flood Warning | FSD | 5 days |
| May 30, 10:15 AM CDT | River Flood Warning | FSD | 5 days |
| May 31, 3:45 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 16, 2:21 AM CDT | Dense Fog Advisory | FSD | 8 hr |
| Jun 27, 12:36 PM CDT | River Flood Warning | FSD | 4 days |
| Jun 27, 12:36 PM CDT | River Flood Warning | FSD | 31 days |
| Jun 27, 3:15 PM CDT | Heat Advisory | FSD | 29 hr |
| Jun 28, 4:50 AM CDT | River Flood Warning | FSD | 31 days |
| Jun 28, 2:02 PM CDT | Heat Advisory | FSD | 31 hr |
| Jun 29, 8:40 AM CDT | River Flood Warning | FSD | 18 hr |
| Jun 29, 11:59 AM CDT | Excessive Heat Warning | FSD | 9 hr |
| Jun 29, 3:18 PM CDT | Heat Advisory | FSD | 30 hr |
| Jul 1, 1:31 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Jul 1, 3:14 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 1, 4:16 PM CDT | Flash Flood Watch | FSD | 9 hr |
| Jul 1, 5:09 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 1, 9:28 PM CDT | Flash Flood Warning | FSD | 3 hr |
| Jul 2, 7:40 AM CDT | River Flood Warning | FSD | 7 days |
| Jul 3, 8:08 AM CDT | Flash Flood Warning | FSD | 3 hr |
| Jul 9, 10:13 PM CDT | River Flood Warning | FSD | 5 days |
| Jul 12, 3:14 PM CDT | Severe Thunderstorm Warning | FSD | 31 min |
| Jul 14, 2:56 AM CDT | Heat Advisory | FSD | 18 hr |
| Jul 14, 3:33 PM CDT | Heat Advisory | FSD | 29 hr |
| Jul 15, 8:33 AM CDT | River Flood Warning | FSD | 11 days |
| Jul 15, 3:38 PM CDT | Excessive Heat Watch | FSD | 50 hr |
| Jul 17, 4:07 AM CDT | Excessive Heat Warning | FSD | 66 hr |
| Jul 17, 4:14 AM CDT | Mesoscale Discussion | SPC | 91 min |
| Jul 17, 4:48 AM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 17, 6:17 AM CDT | Severe Thunderstorm Warning | FSD | 58 min |
| Jul 17, 6:20 AM CDT | Tornado Warning | FSD | 25 min |
| Jul 17, 6:54 AM CDT | Severe Thunderstorm Warning | FSD | 66 min |
| Jul 17, 7:19 AM CDT | Flash Flood Warning | FSD | 116 min |
| Jul 17, 9:09 AM CDT | Mesoscale Discussion | SPC | 96 min |
| Jul 20, 8:39 AM CDT | Severe Thunderstorm Warning | FSD | 36 min |
| Jul 28, 7:27 PM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Jul 28, 9:30 PM CDT | Mesoscale Discussion | SPC | 90 min |
| Aug 9, 6:59 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 9, 7:30 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 11, 2:21 AM CDT | Dense Fog Advisory | FSD | 7 hr |
| Aug 17, 5:12 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 17, 6:14 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Aug 17, 8:26 PM CDT | Mesoscale Discussion | SPC | 94 min |
| Aug 17, 10:32 PM CDT | Mesoscale Discussion | SPC | 88 min |
| Aug 18, 12:00 AM CDT | Mesoscale Discussion | SPC | 90 min |
| Aug 19, 11:05 PM CDT | Mesoscale Discussion | SPC | 115 min |
| Aug 19, 11:56 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Sep 10, 8:33 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Sep 10, 11:31 PM CDT | Mesoscale Discussion | SPC | 89 min |
| Sep 11, 12:24 AM CDT | Flash Flood Warning | FSD | 6 hr |
| Sep 11, 3:14 AM CDT | Flash Flood Warning | FSD | 4 hr |
| Sep 11, 3:31 AM CDT | Areal Flood Warning | FSD | 18 hr |
| Sep 11, 4:07 AM CDT | Flash Flood Watch | FSD | 26 hr |
| Sep 11, 9:10 AM CDT | River Flood Warning | FSD | 16 days |
| Sep 11, 9:10 AM CDT | River Flood Warning | FSD | 21 days |
| Sep 11, 8:03 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Sep 13, 11:43 AM CDT | River Flood Warning | FSD | 21 days |
| Sep 14, 1:53 AM CDT | River Flood Warning | FSD | 7 days |
| Sep 14, 4:50 AM CDT | River Flood Warning | FSD | 21 days |
| Sep 14, 11:34 AM CDT | River Flood Warning | FSD | 5 days |
| Sep 15, 3:19 AM CDT | Dense Fog Advisory | FSD | 9 hr |
| Sep 16, 2:14 PM CDT | River Flood Warning | FSD | 21 days |
| Sep 18, 10:27 PM CDT | Flash Flood Watch | FSD | 7 hr |
| Sep 30, 9:34 PM CDT | Severe Thunderstorm Warning | FSD | 26 min |
| Oct 1, 6:10 PM CDT | River Flood Warning | FSD | 21 days |
| Oct 1, 8:06 PM CDT | River Flood Warning | FSD | 10 days |
| Oct 3, 10:26 AM CDT | River Flood Warning | FSD | 7 days |
| Oct 3, 3:19 PM CDT | Frost Advisory | FSD | 18 hr |
| Oct 12, 9:55 AM CDT | Wind Advisory | FSD | 9 hr |
| Oct 20, 9:20 PM CDT | Wind Advisory | FSD | 43 hr |
| Oct 21, 4:03 AM CDT | High Wind Warning | FSD | 24 hr |
| Oct 21, 11:40 AM CDT | Wind Advisory | FSD | 4 hr |
| Nov 13, 2:44 AM CST | Winter Weather Advisory | FSD | 9 hr |
| Nov 24, 2:01 PM CST | Winter Storm Watch | FSD | 25 hr |
| Nov 25, 4:05 AM CST | Winter Storm Warning | FSD | 56 hr |
| Nov 26, 5:23 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Nov 27, 5:56 PM CST | Winter Weather Advisory | FSD | 4 days |
| Nov 30, 3:28 PM CST | Wind Advisory | FSD | 21 hr |
| Dec 8, 12:21 PM CST | Dense Fog Advisory | FSD | 15 hr |
| Dec 16, 9:14 AM CST | Dense Fog Advisory | FSD | 3 hr |
| Dec 17, 1:48 AM CST | Dense Fog Advisory | FSD | 4 hr |
| Dec 24, 2:24 PM CST | Dense Fog Advisory | FSD | 34 hr |
| Dec 27, 3:18 PM CST | Winter Weather Advisory | FSD | 3 days |
| Dec 28, 3:41 AM CST | Winter Weather Advisory | FSD | 68 hr |
| Dec 28, 10:10 AM CST | River Flood Warning | FSD | 4 days |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe 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.