Alert archive / South Dakota / Mellette County
Weather alerts in Mellette County, South Dakota, 2020
139 weather alerts in 2020, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Mellette County and its neighbors
Each county as a circle sized by its count in 2020. Tap one for its archive.
- Alerts
- 139
- Warnings
- 40
- Watches
- 20
- Advisories
- 31
- Busiest month
- July38 alerts
- Busiest day
- June 7, 202010 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Mellette County, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 29 | 24 | 17% | 12 | 100% | 23 min |
| Flash flood warnings | 1 | 1 | 0% | 0 |
Each office's whole area, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Rapid City, SD: tornado warnings | 11 | 2 | 82% | 11 | 27% | 18 min |
| NWS Rapid City, SD: severe thunderstorm warnings | 415 | 336 | 19% | 828 | 89% | 27 min |
| NWS Rapid City, SD: flash flood warnings | 10 | 7 | 30% | 11 | 91% | 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 | Lasted |
|---|---|---|---|
| Jan 3, 1:55 PM CST | Wind Advisory | UNR | 40 hr |
| Jan 16, 12:07 PM CST | Wind Advisory | UNR | 19 hr |
| Jan 17, 3:19 AM CST | Winter Weather Advisory | UNR | 9 hr |
| Jan 17, 3:22 AM CST | High Wind Warning | UNR | 24 hr |
| Jan 24, 9:30 AM CST | Dense Fog Advisory | UNR | 22 hr |
| Feb 12, 2:38 AM CST | Wind Chill Advisory | UNR | 31 hr |
| Feb 24, 3:28 AM CST | Winter Weather Advisory | UNR | 36 hr |
| Mar 4, 2:19 PM CST | Wind Advisory | UNR | 25 hr |
| Mar 4, 4:51 PM CST | Mesoscale Discussion | SPC | 114 min |
| Mar 5, 3:00 PM CST | Fire Weather Watch | UNR | 36 hr |
| Mar 7, 3:19 AM CST | Red Flag Warning | UNR | 16 hr |
| Mar 13, 4:13 AM CDT | Winter Weather Advisory | UNR | 32 hr |
| Mar 16, 3:09 PM CDT | Winter Storm Watch | UNR | 49 hr |
| Mar 18, 3:10 AM CDT | Winter Weather Advisory | UNR | 40 hr |
| Mar 31, 5:32 AM CDT | Dense Fog Advisory | UNR | 3 hr |
| Mar 31, 3:05 PM CDT | Winter Weather Advisory | UNR | 58 hr |
| Apr 1, 5:06 PM CDT | Special Weather Statement | UNR | 39 min |
| Apr 10, 3:35 PM CDT | Winter Storm Warning | UNR | 42 hr |
| Apr 10, 3:35 PM CDT | Winter Weather Advisory | UNR | 39 hr |
| Apr 20, 3:38 AM CDT | Wind Advisory | UNR | 15 hr |
| Apr 27, 2:44 PM CDT | Wind Advisory | UNR | 30 hr |
| Apr 28, 5:31 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Apr 30, 10:26 PM CDT | Special Weather Statement | UNR | 64 min |
| May 3, 8:57 PM CDT | Severe Thunderstorm Warning | UNR | 63 min |
| May 8, 2:44 PM CDT | Wind Advisory | UNR | 30 hr |
| May 23, 7:53 PM CDT | Mesoscale Discussion | SPC | 97 min |
| May 23, 8:29 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| May 23, 8:44 PM CDT | Severe Thunderstorm Warning | UNR | 46 min |
| Jun 3, 1:35 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Jun 3, 2:05 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 4, 2:25 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Jun 4, 3:27 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 4, 6:55 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Jun 6, 3:33 PM CDT | Mesoscale Discussion | SPC | 117 min |
| Jun 6, 5:49 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 6, 8:28 PM CDT | Severe Thunderstorm Warning | UNR | 62 min |
| Jun 6, 9:26 PM CDT | Severe Thunderstorm Warning | UNR | 64 min |
| Jun 6, 10:04 PM CDT | Severe Thunderstorm Warning | UNR | 56 min |
| Jun 7, 2:04 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Jun 7, 3:31 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 7, 4:14 PM CDT | Special Weather Statement | UNR | 46 min |
| Jun 7, 5:10 PM CDT | Severe Thunderstorm Warning | UNR | 65 min |
| Jun 7, 5:54 PM CDT | Severe Thunderstorm Warning | UNR | 66 min |
| Jun 7, 6:00 PM CDT | Mesoscale Discussion | SPC | 90 min |
| Jun 7, 6:44 PM CDT | Severe Thunderstorm Warning | UNR | 31 min |
| Jun 7, 8:57 PM CDT | Severe Thunderstorm Warning | UNR | 63 min |
| Jun 7, 9:18 PM CDT | Mesoscale Discussion | SPC | 57 min |
| Jun 7, 10:00 PM CDT | Special Weather Statement | UNR | 45 min |
| Jun 9, 5:05 AM CDT | Special Weather Statement | UNR | 55 min |
| Jun 14, 3:36 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 16, 4:08 AM CDT | Wind Advisory | UNR | 17 hr |
| Jun 17, 5:26 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 17, 6:29 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 17, 6:52 PM CDT | Severe Thunderstorm Warning | UNR | 53 min |
| Jun 17, 8:57 PM CDT | Special Weather Statement | UNR | 33 min |
| Jun 17, 9:23 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 17, 11:16 PM CDT | Mesoscale Discussion | SPC | 89 min |
| Jun 20, 3:17 PM CDT | Mesoscale Discussion | SPC | 118 min |
| Jun 20, 3:53 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 21, 2:05 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 25, 3:30 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 29, 4:26 AM CDT | Heat Advisory | UNR | 16 hr |
| Jul 2, 8:46 PM CDT | Mesoscale Discussion | SPC | 59 min |
| Jul 4, 8:33 PM CDT | Special Weather Statement | UNR | 42 min |
| Jul 5, 3:32 PM CDT | Mesoscale Discussion | SPC | 118 min |
| Jul 5, 4:19 PM CDT | Severe Thunderstorm Warning | UNR | 41 min |
| Jul 5, 5:13 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 5, 5:47 PM CDT | Severe Thunderstorm Warning | UNR | 58 min |
| Jul 5, 11:15 PM CDT | Mesoscale Discussion | SPC | 60 min |
| Jul 6, 9:07 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Jul 6, 10:24 PM CDT | Severe Thunderstorm Warning | UNR | 66 min |
| Jul 6, 10:47 PM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Jul 6, 11:14 PM CDT | Severe Thunderstorm Warning | UNR | 61 min |
| Jul 6, 11:54 PM CDT | Severe Thunderstorm Warning | UNR | 51 min |
| Jul 9, 4:46 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 10, 4:26 AM CDT | Special Weather Statement | UNR | 49 min |
| Jul 10, 9:13 AM CDT | Mesoscale Discussion | SPC | 62 min |
| Jul 10, 10:15 AM CDT | Special Weather Statement | UNR | 45 min |
| Jul 10, 10:57 AM CDT | Special Weather Statement | UNR | 48 min |
| Jul 10, 1:26 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 10, 2:08 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 10, 3:43 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 10, 6:31 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Jul 10, 8:19 PM CDT | Severe Thunderstorm Warning | UNR | 56 min |
| Jul 12, 11:09 AM CDT | Severe Thunderstorm Warning | UNR | 21 min |
| Jul 16, 3:06 PM CDT | Heat Advisory | UNR | 29 hr |
| Jul 20, 1:13 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 20, 3:19 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Jul 20, 3:57 PM CDT | Severe Thunderstorm Warning | UNR | 63 min |
| Jul 20, 5:00 PM CDT | Severe Thunderstorm Warning | UNR | 39 min |
| Jul 20, 6:01 PM CDT | Mesoscale Discussion | SPC | 89 min |
| Jul 20, 6:27 PM CDT | Severe Thunderstorm Warning | UNR | 63 min |
| Jul 23, 2:59 AM CDT | Heat Advisory | UNR | 42 hr |
| Jul 24, 2:50 PM CDT | Mesoscale Discussion | SPC | 115 min |
| Jul 24, 3:21 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 24, 5:28 PM CDT | Severe Thunderstorm Warning | UNR | 62 min |
| Jul 24, 6:27 PM CDT | Severe Thunderstorm Warning | UNR | 63 min |
| Jul 24, 7:28 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 29, 8:00 PM CDT | Areal Flood Advisory | UNR | 3 hr |
| Jul 29, 8:52 PM CDT | Flash Flood Warning | UNR | 2 hr |
| Jul 31, 7:41 PM CDT | Severe Thunderstorm Warning | UNR | 79 min |
| Aug 4, 6:05 PM CDT | Mesoscale Discussion | SPC | 115 min |
| Aug 8, 6:00 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 8, 8:58 PM CDT | Mesoscale Discussion | SPC | 92 min |
| Aug 8, 9:27 PM CDT | Severe Thunderstorm Warning | UNR | 63 min |
| Aug 8, 10:01 PM CDT | Severe Thunderstorm Warning | UNR | 59 min |
| Aug 8, 10:55 PM CDT | Severe Thunderstorm Warning | UNR | 58 min |
| Aug 12, 5:28 PM CDT | Mesoscale Discussion | SPC | 92 min |
| Aug 23, 7:57 PM CDT | Special Weather Statement | UNR | 63 min |
| Aug 23, 8:58 PM CDT | Special Weather Statement | UNR | 47 min |
| Aug 24, 3:28 AM CDT | Heat Advisory | UNR | 17 hr |
| Aug 25, 3:01 AM CDT | Heat Advisory | UNR | 17 hr |
| Aug 26, 7:20 PM CDT | Severe Thunderstorm Warning | UNR | 55 min |
| Aug 26, 7:21 PM CDT | Mesoscale Discussion | SPC | 114 min |
| Aug 26, 8:09 PM CDT | Severe Thunderstorm Warning | UNR | 20 min |
| Aug 26, 8:13 PM CDT | Severe Thunderstorm Warning | UNR | 62 min |
| Aug 27, 6:31 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 27, 9:20 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Aug 27, 11:20 PM CDT | Special Weather Statement | UNR | 40 min |
| Aug 30, 3:22 PM CDT | Mesoscale Discussion | SPC | 113 min |
| Sep 13, 3:03 PM CDT | Red Flag Warning | UNR | 30 hr |
| Sep 14, 2:31 AM CDT | Dense Fog Advisory | UNR | 6 hr |
| Sep 25, 2:58 PM CDT | Red Flag Warning | UNR | 27 hr |
| Sep 26, 8:32 PM CDT | Wind Advisory | UNR | 23 hr |
| Sep 29, 2:34 PM CDT | Wind Advisory | UNR | 29 hr |
| Oct 13, 2:50 PM CDT | High Wind Warning | UNR | 28 hr |
| Oct 14, 7:02 PM CDT | Wind Advisory | UNR | 82 min |
| Oct 22, 3:42 PM CDT | Winter Storm Watch | UNR | 23 hr |
| Oct 23, 3:05 PM CDT | Winter Storm Warning | UNR | 44 hr |
| Oct 23, 3:05 PM CDT | Winter Weather Advisory | UNR | 47 hr |
| Oct 30, 2:46 PM CDT | Wind Advisory | UNR | 28 hr |
| Nov 6, 2:42 AM CST | Red Flag Warning | UNR | 15 hr |
| Nov 7, 2:23 AM CST | High Wind Watch | UNR | 12 hr |
| Nov 7, 2:39 PM CST | High Wind Warning | UNR | 21 hr |
| Nov 13, 3:14 PM CST | Wind Advisory | UNR | 32 hr |
| Dec 21, 2:45 PM CST | High Wind Watch | UNR | 13 hr |
| Dec 22, 4:13 AM CST | High Wind Warning | UNR | 34 hr |
| Dec 22, 2:25 PM CST | Winter Weather Advisory | UNR | 28 hr |
| Dec 28, 4:06 AM CST | Winter Weather Advisory | UNR | 37 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 | 29 |
| Severe Thunderstorm Watch | 15 |
| Mesoscale Discussion | 35 |
| Special Weather Statement | 13 |
| Flooding | |
| Flash Flood Warning | 1 |
| Areal Flood Advisory | 1 |
| Winter | |
| Winter Storm Warning | 2 |
| Winter Storm Watch | 2 |
| Winter Weather Advisory | 9 |
| Heat | |
| Heat Advisory | 5 |
| Cold | |
| Wind Chill Advisory | 1 |
| Wind and dust | |
| High Wind Warning | 4 |
| High Wind Watch | 2 |
| Wind Advisory | 12 |
| Fire | |
| Red Flag Warning | 4 |
| Fire Weather Watch | 1 |
| Fog and smoke | |
| Dense Fog Advisory | 3 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20192021
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.