Alert archive / South Carolina / Williamsburg County
Weather alerts in Williamsburg County, South Carolina, 2021
91 weather alerts in 2021, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Williamsburg County and its neighbors
Each county as a circle sized by its count in 2021. Tap one for its archive.
- Alerts
- 91
- Warnings
- 16
- Watches
- 11
- Advisories
- 24
- Busiest month
- July20 alerts
- Busiest day
- July 8, 20216 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 Williamsburg County in 2021 had a tornado report inside them.
Williamsburg County, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 1 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 7 | 3 | 57% | 1 | 100% | 13 min |
| Flash flood warnings | 0 | 0 |
Each office's whole area, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Wilmington, NC: tornado warnings | 12 | 2 | 83% | 5 | 80% | 1 min |
| NWS Wilmington, NC: severe thunderstorm warnings | 46 | 23 | 50% | 57 | 79% | 19 min |
| NWS Wilmington, NC: flash flood warnings | 8 | 5 | 38% | 7 | 86% | 99 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, Eastern Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Dec 31, 11:55 PM EST | Dense Fog Advisory | ILM | 10 hr |
| Jan 7, 4:08 PM EST | River Flood Warning | ILM | 21 days |
| Jan 16, 12:29 AM EST | Dense Fog Advisory | ILM | 6 hr |
| Feb 4, 9:25 AM EST | River Flood Warning | CHS | 39 days |
| Feb 11, 5:40 AM EST | Dense Fog Advisory | ILM | 3 hr |
| Feb 11, 10:35 PM EST | Dense Fog Advisory | ILM | 4 hr |
| Feb 16, 11:39 AM EST | River Flood Warning | ILM | 21 days |
| Feb 18, 3:16 AM EST | Flash Flood Watch | ILM | 28 hr |
| Feb 18, 5:11 PM EST | Areal Flood Advisory | ILM | 3 hr |
| Feb 18, 6:12 PM EST | Areal Flood Advisory | ILM | 82 min |
| Feb 22, 11:27 PM EST | Dense Fog Advisory | ILM | 7 hr |
| Mar 1, 10:56 AM EST | Special Weather Statement | ILM | 64 min |
| Mar 1, 11:25 AM EST | Special Weather Statement | ILM | 65 min |
| Mar 19, 10:44 AM EDT | River Flood Warning | CHS | 32 days |
| Mar 26, 1:56 PM EDT | Mesoscale Discussion | SPC | 94 min |
| Mar 28, 5:03 PM EDT | Special Weather Statement | ILM | 42 min |
| Mar 28, 5:51 PM EDT | Mesoscale Discussion | SPC | 54 min |
| Mar 31, 2:22 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Mar 31, 5:28 PM EDT | Special Weather Statement | ILM | 32 min |
| Mar 31, 5:58 PM EDT | Severe Thunderstorm Warning | ILM | 32 min |
| Mar 31, 6:24 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Mar 31, 9:08 PM EDT | Special Weather Statement | ILM | 52 min |
| Apr 1, 2:45 PM EDT | Freeze Warning | ILM | 17 hr |
| Apr 2, 8:21 AM EDT | Freeze Warning | ILM | 25 hr |
| Apr 20, 3:42 PM EDT | Fire Weather Watch | ILM | 12 hr |
| Apr 21, 3:17 AM EDT | Red Flag Warning | ILM | 16 hr |
| May 3, 4:26 PM EDT | Mesoscale Discussion | SPC | 94 min |
| May 3, 5:25 PM EDT | Severe Thunderstorm Warning | ILM | 21 min |
| May 3, 5:44 PM EDT | Special Weather Statement | ILM | 31 min |
| May 3, 6:13 PM EDT | Severe Thunderstorm Warning | ILM | 32 min |
| May 4, 4:16 PM EDT | Mesoscale Discussion | SPC | 119 min |
| May 4, 7:04 PM EDT | Severe Thunderstorm Warning | ILM | 41 min |
| May 4, 7:42 PM EDT | Severe Thunderstorm Warning | ILM | 33 min |
| May 4, 7:59 PM EDT | Mesoscale Discussion | SPC | 61 min |
| May 7, 3:30 PM EDT | Fire Weather Watch | ILM | 15 hr |
| May 29, 12:37 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jun 4, 7:28 PM EDT | Areal Flood Advisory | ILM | 92 min |
| Jun 4, 9:18 PM EDT | Areal Flood Advisory | ILM | 89 min |
| Jun 9, 5:33 PM EDT | Special Weather Statement | ILM | 27 min |
| Jun 12, 1:14 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 15, 12:57 PM EDT | Mesoscale Discussion | SPC | 63 min |
| Jun 15, 1:58 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 15, 4:09 PM EDT | Mesoscale Discussion | SPC | 96 min |
| Jun 20, 3:35 AM EDT | Flash Flood Watch | ILM | 19 hr |
| Jun 20, 6:28 PM EDT | Special Weather Statement | ILM | 47 min |
| Jun 25, 4:41 PM EDT | Special Weather Statement | ILM | 34 min |
| Jun 25, 4:59 PM EDT | Special Weather Statement | ILM | 31 min |
| Jun 25, 5:33 PM EDT | Special Weather Statement | ILM | 27 min |
| Jun 25, 6:01 PM EDT | Areal Flood Advisory | ILM | 119 min |
| Jun 28, 2:21 PM EDT | Mesoscale Discussion | SPC | 114 min |
| Jul 8, 1:38 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 8, 2:01 AM EDT | Tornado Watch | SPC | 7 hr |
| Jul 8, 3:50 AM EDT | Areal Flood Advisory | ILM | 3 hr |
| Jul 8, 4:31 AM EDT | Tornado Warning | ILM | 29 min |
| Jul 8, 5:25 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 8, 6:27 AM EDT | Areal Flood Advisory | ILM | 2 hr |
| Jul 9, 5:26 PM EDT | Special Weather Statement | ILM | 34 min |
| Jul 9, 5:40 PM EDT | Mesoscale Discussion | SPC | 95 min |
| Jul 9, 5:56 PM EDT | Severe Thunderstorm Warning | ILM | 21 min |
| Jul 9, 6:01 PM EDT | Special Weather Statement | ILM | 29 min |
| Jul 9, 6:15 PM EDT | Special Weather Statement | ILM | 30 min |
| Jul 9, 6:49 PM EDT | Special Weather Statement | ILM | 26 min |
| Jul 13, 1:05 PM EDT | Special Weather Statement | ILM | 25 min |
| Jul 18, 3:24 PM EDT | Special Weather Statement | ILM | 66 min |
| Jul 18, 3:58 PM EDT | Severe Thunderstorm Warning | ILM | 32 min |
| Jul 22, 4:27 PM EDT | Areal Flood Advisory | ILM | 81 min |
| Jul 28, 6:07 PM EDT | Mesoscale Discussion | SPC | 83 min |
| Jul 29, 3:16 PM EDT | Heat Advisory | ILM | 28 hr |
| Jul 31, 3:13 AM EDT | Heat Advisory | ILM | 16 hr |
| Jul 31, 1:40 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 1, 3:47 AM EDT | Heat Advisory | ILM | 15 hr |
| Aug 1, 12:37 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 1, 9:07 PM EDT | Special Weather Statement | ILM | 53 min |
| Aug 1, 9:33 PM EDT | Areal Flood Advisory | ILM | 87 min |
| Aug 1, 10:10 PM EDT | Special Weather Statement | ILM | 50 min |
| Aug 3, 3:20 AM EDT | Flash Flood Watch | ILM | 4 min |
| Aug 3, 3:30 AM EDT | Flash Flood Watch | ILM | 24 hr |
| Aug 9, 5:18 AM EDT | Dense Fog Advisory | ILM | 4 hr |
| Aug 24, 4:31 PM EDT | Special Weather Statement | ILM | 29 min |
| Aug 24, 5:35 PM EDT | Areal Flood Advisory | ILM | 115 min |
| Aug 24, 5:50 PM EDT | Special Weather Statement | ILM | 25 min |
| Aug 24, 5:54 PM EDT | Special Weather Statement | ILM | 36 min |
| Sep 21, 3:12 AM EDT | Flash Flood Watch | ILM | 39 hr |
| Oct 28, 6:36 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Nov 13, 3:00 PM EST | Frost Advisory | ILM | 17 hr |
| Nov 15, 2:10 PM EST | Frost Advisory | ILM | 18 hr |
| Nov 22, 4:18 AM EST | Freeze Watch | ILM | 22 hr |
| Nov 23, 2:18 AM EST | Freeze Warning | ILM | 31 hr |
| Dec 6, 2:11 AM EST | Dense Fog Advisory | ILM | 8 hr |
| Dec 8, 10:38 PM EST | Dense Fog Advisory | ILM | 10 hr |
| Dec 18, 3:21 AM EST | Dense Fog Advisory | ILM | 6 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 | 7 |
| Tornado Warning | 1 |
| Severe Thunderstorm Watch | 2 |
| Tornado Watch | 1 |
| Mesoscale Discussion | 18 |
| Special Weather Statement | 22 |
| Flooding | |
| River Flood Warning | 4 |
| Flash Flood Watch | 5 |
| Areal Flood Advisory | 10 |
| Heat | |
| Heat Advisory | 3 |
| Cold | |
| Freeze Warning | 3 |
| Freeze Watch | 1 |
| Frost Advisory | 2 |
| Fire | |
| Red Flag Warning | 1 |
| Fire Weather Watch | 2 |
| Fog and smoke | |
| Dense Fog Advisory | 9 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20202022
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.