Alert archive / South Dakota / Gregory County
Weather alerts in Gregory County, South Dakota, 2011
89 weather alerts in 2011, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Gregory County and its neighbors
Each county as a circle sized by its count in 2011. Tap one for its archive.
- Alerts
- 89
- Warnings
- 24
- Watches
- 18
- Advisories
- 28
- Busiest month
- June17 alerts
- Busiest day
- May 30, 20117 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Gregory County, 2011
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 16 | 8 | 50% | 2 | 100% | 20 min |
| Flash flood warnings | 3 | 2 | 33% | 0 |
Each office's whole area, 2011
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sioux Falls, SD: tornado warnings | 38 | 10 | 74% | 15 | 73% | 12 min |
| NWS Sioux Falls, SD: severe thunderstorm warnings | 274 | 187 | 32% | 337 | 89% | 19 min |
| NWS Sioux Falls, SD: flash flood warnings | 36 | 26 | 28% | 54 | 91% | 61 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, 10:00 AM CST | Wind Advisory | FSD | 6 hr |
| Jan 8, 2:24 PM CST | Winter Weather Advisory | FSD | 64 hr |
| Jan 11, 3:37 AM CST | Wind Chill Advisory | FSD | 8 hr |
| Jan 11, 3:14 PM CST | Wind Chill Advisory | FSD | 19 hr |
| Jan 29, 3:39 PM CST | Winter Weather Advisory | FSD | 3 days |
| Jan 31, 3:17 PM CST | Wind Chill Warning | FSD | 45 hr |
| Feb 7, 3:48 AM CST | Wind Chill Advisory | FSD | 32 hr |
| Feb 8, 2:37 PM CST | Wind Chill Advisory | FSD | 21 hr |
| Feb 12, 2:41 PM CST | Wind Advisory | FSD | 36 hr |
| Feb 17, 10:35 AM CST | Wind Advisory | FSD | 10 hr |
| Feb 18, 4:18 AM CST | Winter Storm Watch | FSD | 35 hr |
| Feb 19, 3:37 PM CST | Blizzard Warning | FSD | 30 hr |
| Feb 19, 11:25 PM CST | Mesoscale Discussion | SPC | 5 hr |
| Feb 20, 3:25 PM CST | Winter Weather Advisory | FSD | 12 hr |
| Mar 11, 4:00 AM CST | Wind Advisory | FSD | 32 hr |
| Mar 19, 2:51 AM CDT | Wind Advisory | FSD | 16 hr |
| Mar 20, 2:05 AM CDT | Severe Thunderstorm Warning | FSD | 25 min |
| Mar 20, 2:28 AM CDT | Severe Thunderstorm Warning | FSD | 32 min |
| Apr 3, 4:17 AM CDT | Wind Advisory | FSD | 36 hr |
| Apr 13, 3:19 AM CDT | Winter Storm Watch | FSD | 36 hr |
| Apr 14, 3:39 PM CDT | Winter Storm Warning | FSD | 30 hr |
| Apr 21, 3:24 AM CDT | Wind Advisory | FSD | 12 hr |
| Apr 29, 9:11 PM CDT | Wind Advisory | FSD | 28 hr |
| May 1, 3:55 AM CDT | Wind Advisory | FSD | 13 hr |
| May 8, 5:06 PM CDT | Mesoscale Discussion | SPC | 54 min |
| May 8, 6:13 PM CDT | Tornado Watch | SPC | 6 hr |
| May 8, 8:47 PM CDT | Mesoscale Discussion | SPC | 58 min |
| May 24, 3:30 PM CDT | Wind Advisory | FSD | 27 hr |
| May 29, 10:58 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| May 29, 11:39 PM CDT | Severe Thunderstorm Warning | FSD | 36 min |
| May 30, 1:40 PM CDT | Mesoscale Discussion | SPC | 95 min |
| May 30, 2:08 PM CDT | Tornado Watch | SPC | 7 hr |
| May 30, 5:08 PM CDT | Severe Thunderstorm Warning | FSD | 37 min |
| May 30, 6:17 PM CDT | Mesoscale Discussion | SPC | 118 min |
| May 30, 6:38 PM CDT | Severe Thunderstorm Warning | FSD | 52 min |
| Jun 6, 4:50 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 6, 8:10 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Jun 14, 4:44 PM CDT | Severe Thunderstorm Warning | FSD | 46 min |
| Jun 14, 4:46 PM CDT | Mesoscale Discussion | SPC | 59 min |
| Jun 16, 8:26 PM CDT | Mesoscale Discussion | SPC | 64 min |
| Jun 19, 3:40 AM CDT | Flash Flood Watch | FSD | 55 hr |
| Jun 20, 4:33 PM CDT | Mesoscale Discussion | SPC | 87 min |
| Jun 20, 6:49 PM CDT | Flash Flood Warning | FSD | 3 hr |
| Jun 20, 6:53 PM CDT | Tornado Watch | SPC | 6 hr |
| Jun 20, 9:59 PM CDT | Flash Flood Warning | FSD | 3 hr |
| Jun 20, 11:22 PM CDT | Areal Flood Warning | FSD | 36 hr |
| Jun 24, 5:57 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 26, 6:08 AM CDT | Mesoscale Discussion | SPC | 97 min |
| Jun 26, 6:16 AM CDT | Mesoscale Discussion | SPC | 59 min |
| Jun 26, 1:03 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 26, 2:30 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 29, 3:18 PM CDT | Heat Advisory | FSD | 28 hr |
| Jun 30, 10:07 PM CDT | Severe Thunderstorm Warning | FSD | 38 min |
| Jun 30, 11:38 PM CDT | Severe Thunderstorm Warning | FSD | 37 min |
| Jul 4, 4:28 AM CDT | Flash Flood Watch | FSD | 23 hr |
| Jul 4, 11:14 PM CDT | Mesoscale Discussion | SPC | 91 min |
| Jul 4, 11:41 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 8, 4:29 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 9, 6:09 PM CDT | Mesoscale Discussion | SPC | 66 min |
| Jul 12, 3:26 AM CDT | Flash Flood Warning | FSD | 3 hr |
| Jul 14, 3:31 PM CDT | Excessive Heat Watch | FSD | 12 hr |
| Jul 15, 3:42 AM CDT | Excessive Heat Warning | FSD | 6 days |
| Jul 22, 6:22 PM CDT | Mesoscale Discussion | SPC | 53 min |
| Jul 26, 5:43 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 26, 8:17 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 27, 11:57 PM CDT | Severe Thunderstorm Warning | FSD | 33 min |
| Jul 28, 12:36 AM CDT | Severe Thunderstorm Warning | FSD | 39 min |
| Jul 30, 3:33 PM CDT | Heat Advisory | FSD | 52 hr |
| Aug 2, 12:42 AM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Aug 6, 2:31 AM CDT | Severe Thunderstorm Warning | FSD | 29 min |
| Aug 7, 7:49 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 7, 9:39 PM CDT | Severe Thunderstorm Warning | FSD | 66 min |
| Aug 11, 3:05 PM CDT | Tornado Watch | SPC | 5 hr |
| Aug 11, 6:19 PM CDT | Severe Thunderstorm Warning | FSD | 41 min |
| Aug 11, 6:59 PM CDT | Severe Thunderstorm Warning | FSD | 46 min |
| Aug 11, 7:19 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Aug 11, 7:29 PM CDT | Severe Thunderstorm Warning | FSD | 46 min |
| Aug 18, 11:39 AM CDT | Severe Thunderstorm Warning | FSD | 25 min |
| Aug 28, 5:16 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 3, 1:20 AM CDT | Mesoscale Discussion | SPC | 85 min |
| Sep 19, 3:28 PM CDT | Wind Advisory | FSD | 34 hr |
| Oct 4, 3:13 PM CDT | Wind Advisory | FSD | 3 days |
| Nov 4, 3:37 AM CDT | Wind Advisory | FSD | 14 hr |
| Nov 4, 3:37 AM CDT | Wind Advisory | FSD | 47 hr |
| Nov 15, 3:26 AM CST | Wind Advisory | FSD | 14 hr |
| Nov 25, 4:30 AM CST | Wind Advisory | FSD | 41 hr |
| Dec 13, 9:53 PM CST | Winter Weather Advisory | FSD | 3 min |
| Dec 13, 9:56 PM CST | Winter Weather Advisory | FSD | 9 hr |
| Dec 30, 3:15 PM CST | Wind Advisory | FSD | 57 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 | 16 |
| Severe Thunderstorm Watch | 9 |
| Tornado Watch | 4 |
| Mesoscale Discussion | 19 |
| Flooding | |
| Areal Flood Warning | 1 |
| Flash Flood Warning | 3 |
| Flash Flood Watch | 2 |
| Winter | |
| Blizzard Warning | 1 |
| Winter Storm Warning | 1 |
| Winter Storm Watch | 2 |
| Winter Weather Advisory | 5 |
| Heat | |
| Excessive Heat Warning | 1 |
| Excessive Heat Watch | 1 |
| Heat Advisory | 2 |
| Cold | |
| Wind Chill Warning | 1 |
| Wind Chill Advisory | 4 |
| Wind and dust | |
| Wind Advisory | 17 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20102012
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.