Alert archive / South Dakota / Union County
Weather alerts in Union County, South Dakota, 2015
107 weather alerts in 2015, 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 2015. Tap one for its archive.
- Alerts
- 107
- Warnings
- 27
- Watches
- 20
- Advisories
- 30
- Busiest month
- January17 alerts
- Busiest day
- May 10, 20157 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 2015 had a tornado report inside them.
Union County, 2015
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 1 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 14 | 9 | 36% | 4 | 100% | 15 min |
| Flash flood warnings | 1 | 1 | 0% | 1 | 100% | 39 min |
Each office's whole area, 2015
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sioux Falls, SD: tornado warnings | 30 | 13 | 57% | 25 | 68% | 14 min |
| NWS Sioux Falls, SD: severe thunderstorm warnings | 175 | 123 | 30% | 220 | 86% | 20 min |
| NWS Sioux Falls, SD: flash flood warnings | 19 | 13 | 32% | 19 | 95% | 37 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 2, 3:25 PM CST | Wind Chill Advisory | FSD | 69 hr |
| Jan 3, 4:19 AM CST | Winter Weather Advisory | FSD | 23 hr |
| Jan 3, 3:36 PM CST | Winter Storm Watch | FSD | 37 hr |
| Jan 3, 6:28 PM CST | Blizzard Warning | FSD | 7 hr |
| Jan 3, 6:28 PM CST | Winter Weather Advisory | FSD | 9 hr |
| Jan 5, 4:19 AM CST | Winter Weather Advisory | FSD | 15 hr |
| Jan 5, 5:16 PM CST | Wind Chill Advisory | FSD | 19 hr |
| Jan 6, 4:25 AM CST | Wind Chill Advisory | FSD | 47 hr |
| Jan 7, 4:36 AM CST | Blizzard Watch | FSD | 23 hr |
| Jan 7, 3:26 PM CST | Winter Weather Advisory | FSD | 37 hr |
| Jan 8, 3:54 AM CST | Wind Chill Advisory | FSD | 30 hr |
| Jan 8, 1:39 PM CST | Blizzard Warning | FSD | 8 hr |
| Jan 12, 3:34 AM CST | Wind Chill Advisory | FSD | 31 hr |
| Jan 16, 2:58 PM CST | Wind Advisory | FSD | 25 hr |
| Jan 28, 12:36 PM CST | Wind Advisory | FSD | 20 hr |
| Jan 31, 3:50 AM CST | Winter Weather Advisory | FSD | 35 hr |
| Jan 31, 9:53 AM CST | Winter Storm Warning | FSD | 32 hr |
| Feb 9, 3:25 PM CST | Freezing Rain Advisory | FSD | 23 hr |
| Feb 17, 2:54 AM CST | Wind Chill Advisory | FSD | 33 hr |
| Feb 24, 2:51 PM CST | Winter Weather Advisory | FSD | 24 hr |
| Feb 24, 2:55 PM CST | Winter Weather Advisory | FSD | 24 hr |
| Feb 25, 3:11 PM CST | Wind Chill Advisory | FSD | 21 hr |
| Mar 28, 3:06 PM CDT | Wind Advisory | FSD | 28 hr |
| Apr 1, 3:50 PM CDT | Mesoscale Discussion | SPC | 115 min |
| Apr 1, 5:57 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Apr 12, 4:45 PM CDT | Severe Thunderstorm Warning | FSD | 30 min |
| Apr 12, 5:42 PM CDT | Mesoscale Discussion | SPC | 63 min |
| Apr 12, 6:02 PM CDT | Severe Thunderstorm Warning | FSD | 28 min |
| Apr 20, 3:31 AM CDT | Wind Advisory | FSD | 15 hr |
| Apr 22, 3:39 AM CDT | Freeze Warning | FSD | 28 hr |
| May 3, 3:57 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 10, 10:24 AM CDT | Mesoscale Discussion | SPC | 3 hr |
| May 10, 10:46 AM CDT | Tornado Watch | SPC | 8 hr |
| May 10, 1:40 PM CDT | Severe Thunderstorm Warning | FSD | 35 min |
| May 10, 2:02 PM CDT | Severe Thunderstorm Warning | FSD | 28 min |
| May 10, 2:43 PM CDT | Mesoscale Discussion | SPC | 92 min |
| May 10, 2:51 PM CDT | Tornado Warning | FSD | 24 min |
| May 10, 3:15 PM CDT | Severe Thunderstorm Warning | FSD | 30 min |
| May 16, 2:10 PM CDT | Mesoscale Discussion | SPC | 95 min |
| May 18, 2:43 PM CDT | Frost Advisory | FSD | 17 hr |
| May 25, 6:06 PM CDT | Mesoscale Discussion | SPC | 114 min |
| Jun 3, 3:01 AM CDT | Mesoscale Discussion | SPC | 89 min |
| Jun 6, 2:32 PM CDT | Mesoscale Discussion | SPC | 88 min |
| Jun 6, 3:12 PM CDT | Flash Flood Watch | FSD | 9 hr |
| Jun 6, 3:40 PM CDT | Tornado Watch | SPC | 5 hr |
| Jun 6, 6:32 PM CDT | Severe Thunderstorm Warning | FSD | 28 min |
| Jun 6, 6:34 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Jun 6, 7:31 PM CDT | Severe Thunderstorm Warning | FSD | 44 min |
| Jun 6, 8:11 PM CDT | Mesoscale Discussion | SPC | 64 min |
| Jun 6, 8:45 PM CDT | Tornado Watch | SPC | 4 hr |
| Jun 6, 10:11 PM CDT | Flash Flood Warning | FSD | 3 hr |
| Jun 6, 11:00 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 9, 7:59 PM CDT | Mesoscale Discussion | SPC | 91 min |
| Jun 10, 2:42 PM CDT | Flash Flood Watch | FSD | 19 hr |
| Jun 14, 12:51 PM CDT | Mesoscale Discussion | SPC | 114 min |
| Jun 19, 10:57 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 22, 5:20 AM CDT | Severe Thunderstorm Warning | FSD | 40 min |
| Jun 22, 5:34 AM CDT | High Wind Warning | FSD | 2 hr |
| Jul 3, 6:19 AM CDT | Dense Fog Advisory | FSD | 3 hr |
| Jul 5, 3:46 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Jul 5, 7:42 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 5, 9:57 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 6, 1:01 AM CDT | Mesoscale Discussion | SPC | 29 min |
| Jul 6, 1:11 AM CDT | Severe Thunderstorm Warning | FSD | 49 min |
| Jul 11, 4:00 AM CDT | Heat Advisory | FSD | 39 hr |
| Jul 16, 6:44 PM CDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 17, 8:55 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 17, 8:57 PM CDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 17, 10:53 PM CDT | Severe Thunderstorm Warning | FSD | 52 min |
| Jul 17, 11:26 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 23, 3:33 AM CDT | Heat Advisory | FSD | 39 hr |
| Jul 25, 10:54 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 28, 3:37 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 9, 1:05 PM CDT | Mesoscale Discussion | SPC | 115 min |
| Aug 9, 1:42 PM CDT | Severe Thunderstorm Watch | SPC | 9 hr |
| Aug 9, 4:03 PM CDT | Mesoscale Discussion | SPC | 117 min |
| Aug 9, 7:09 PM CDT | Severe Thunderstorm Warning | FSD | 51 min |
| Aug 9, 7:15 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 9, 7:58 PM CDT | Severe Thunderstorm Warning | FSD | 47 min |
| Aug 9, 9:08 PM CDT | Severe Thunderstorm Warning | FSD | 67 min |
| Aug 9, 9:15 PM CDT | Severe Thunderstorm Warning | FSD | 20 min |
| Aug 16, 10:56 AM CDT | Flash Flood Watch | FSD | 9 hr |
| Aug 16, 4:01 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Aug 18, 3:18 AM CDT | Flash Flood Watch | FSD | 9 hr |
| Aug 22, 2:13 PM CDT | Mesoscale Discussion | SPC | 62 min |
| Aug 22, 2:35 PM CDT | Tornado Watch | SPC | 7 hr |
| Sep 9, 5:10 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 19, 4:46 AM CDT | Dense Fog Advisory | FSD | 6 hr |
| Sep 23, 4:14 AM CDT | Flash Flood Watch | FSD | 27 hr |
| Oct 11, 4:20 PM CDT | Wind Advisory | FSD | 26 hr |
| Oct 15, 3:34 AM CDT | Freeze Warning | FSD | 29 hr |
| Nov 10, 3:43 AM CST | High Wind Watch | FSD | 11 hr |
| Nov 10, 3:02 PM CST | High Wind Warning | FSD | 39 hr |
| Nov 10, 3:02 PM CST | Wind Advisory | FSD | 51 hr |
| Nov 18, 3:52 AM CST | Wind Advisory | FSD | 38 hr |
| Nov 18, 3:10 PM CST | Winter Storm Watch | FSD | 37 hr |
| Nov 19, 3:44 PM CST | Winter Storm Warning | FSD | 30 hr |
| Nov 20, 9:00 AM CST | Mesoscale Discussion | SPC | 5 hr |
| Nov 25, 2:59 PM CST | Winter Weather Advisory | FSD | 26 hr |
| Nov 28, 2:41 PM CST | Winter Storm Watch | FSD | 25 hr |
| Nov 29, 3:26 PM CST | Winter Storm Warning | FSD | 42 hr |
| Nov 30, 12:03 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Dec 24, 3:47 PM CST | Winter Storm Warning | FSD | 50 hr |
| Dec 24, 3:47 PM CST | Winter Weather Advisory | FSD | 47 hr |
| Dec 26, 2:51 PM CST | Winter Storm Watch | FSD | 37 hr |
| Dec 27, 3:19 PM CST | Winter Storm Warning | FSD | 46 hr |
| Dec 28, 3:39 AM CST | Winter Weather Advisory | FSD | 31 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
| Product | Alerts |
|---|---|
| Severe storms | |
| Severe Thunderstorm Warning | 14 |
| Tornado Warning | 1 |
| Severe Thunderstorm Watch | 5 |
| Tornado Watch | 4 |
| Mesoscale Discussion | 30 |
| Flooding | |
| Flash Flood Warning | 1 |
| Flash Flood Watch | 5 |
| Winter | |
| Blizzard Warning | 2 |
| Winter Storm Warning | 5 |
| Blizzard Watch | 1 |
| Winter Storm Watch | 4 |
| Freezing Rain Advisory | 1 |
| Winter Weather Advisory | 10 |
| Heat | |
| Heat Advisory | 2 |
| Cold | |
| Freeze Warning | 2 |
| Frost Advisory | 1 |
| Wind Chill Advisory | 7 |
| Wind and dust | |
| High Wind Warning | 2 |
| High Wind Watch | 1 |
| Wind Advisory | 7 |
| Fog and smoke | |
| Dense Fog Advisory | 2 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20142016
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.