Alert archive / South Carolina / Sumter County
Weather alerts in Sumter 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.
Sumter County and its neighbors
Each county as a circle sized by its count in 2021. Tap one for its archive.
- Alerts
- 91
- Warnings
- 19
- Watches
- 9
- Advisories
- 41
- Busiest month
- July15 alerts
- Busiest day
- May 3, 20217 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Sumter County, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 15 | 10 | 33% | 13 | 85% | 29 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 Columbia, SC: tornado warnings | 17 | 5 | 71% | 15 | 87% | 10 min |
| NWS Columbia, SC: severe thunderstorm warnings | 80 | 50 | 38% | 156 | 76% | 16 min |
| NWS Columbia, SC: flash flood warnings | 6 | 3 | 50% | 11 | 82% | 32 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, 10:10 PM EST | Dense Fog Advisory | CAE | 10 hr |
| Jan 1, 3:35 PM EST | Flash Flood Watch | CAE | 34 hr |
| Jan 13, 3:25 AM EST | Dense Fog Advisory | CAE | 9 hr |
| Jan 15, 12:41 PM EST | Lake Wind Advisory | CAE | 29 hr |
| Jan 15, 9:18 PM EST | Dense Fog Advisory | CAE | 7 hr |
| Jan 25, 4:13 PM EST | Dense Fog Advisory | CAE | 12 hr |
| Jan 28, 12:53 AM EST | Lake Wind Advisory | CAE | 11 hr |
| Feb 17, 2:01 PM EST | Flash Flood Watch | CAE | 41 hr |
| Feb 22, 8:43 PM EST | Dense Fog Advisory | CAE | 3 hr |
| Feb 23, 12:07 AM EST | Dense Fog Advisory | CAE | 3 hr |
| Mar 17, 1:06 AM EDT | Areal Flood Advisory | CAE | 114 min |
| Mar 26, 1:56 PM EDT | Mesoscale Discussion | SPC | 94 min |
| Mar 27, 6:32 AM EDT | Dense Fog Advisory | CAE | 3 hr |
| Mar 27, 2:40 PM EDT | Lake Wind Advisory | CAE | 36 hr |
| Mar 28, 12:38 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Mar 28, 3:49 PM EDT | Severe Thunderstorm Warning | CAE | 41 min |
| Mar 28, 4:23 PM EDT | Severe Thunderstorm Warning | CAE | 37 min |
| Mar 31, 2:11 PM EDT | Freeze Watch | CAE | 13 hr |
| Mar 31, 2:22 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Mar 31, 6:24 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Apr 1, 3:02 AM EDT | Freeze Warning | CAE | 30 hr |
| Apr 2, 9:05 AM EDT | Freeze Warning | CAE | 24 hr |
| Apr 3, 2:36 PM EDT | Frost Advisory | CAE | 17 hr |
| Apr 20, 2:02 PM EDT | Fire Weather Watch | CAE | 12 hr |
| Apr 21, 1:17 AM EDT | Lake Wind Advisory | CAE | 31 hr |
| Apr 21, 1:37 AM EDT | Red Flag Warning | CAE | 18 hr |
| Apr 22, 2:19 PM EDT | Frost Advisory | CAE | 18 hr |
| May 3, 1:25 PM EDT | Tornado Watch | SPC | 6 hr |
| May 3, 4:03 PM EDT | Severe Thunderstorm Warning | CAE | 27 min |
| May 3, 4:19 PM EDT | Severe Thunderstorm Warning | CAE | 26 min |
| May 3, 4:26 PM EDT | Mesoscale Discussion | SPC | 94 min |
| May 3, 4:41 PM EDT | Severe Thunderstorm Warning | CAE | 34 min |
| May 3, 4:44 PM EDT | Severe Thunderstorm Warning | CAE | 31 min |
| May 3, 5:14 PM EDT | Severe Thunderstorm Warning | CAE | 46 min |
| May 4, 4:16 PM EDT | Mesoscale Discussion | SPC | 119 min |
| May 4, 4:56 PM EDT | Severe Thunderstorm Watch | SPC | 3 hr |
| May 4, 6:07 PM EDT | Severe Thunderstorm Warning | CAE | 53 min |
| May 7, 3:09 AM EDT | Lake Wind Advisory | CAE | 17 hr |
| May 9, 4:08 AM EDT | Lake Wind Advisory | CAE | 15 hr |
| May 29, 12:37 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jun 12, 1:14 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 14, 9:27 PM EDT | Severe Thunderstorm Warning | CAE | 48 min |
| 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, 2:03 AM EDT | Flash Flood Watch | CAE | 17 hr |
| Jun 20, 2:43 PM EDT | Mesoscale Discussion | SPC | 92 min |
| Jun 20, 5:29 PM EDT | Special Weather Statement | CAE | 46 min |
| Jun 28, 11:34 AM EDT | Lake Wind Advisory | CAE | 16 hr |
| Jul 1, 6:28 PM EDT | Special Weather Statement | CAE | 32 min |
| Jul 7, 1:14 PM EDT | Lake Wind Advisory | CAE | 23 hr |
| Jul 8, 2:10 AM EDT | Severe Thunderstorm Warning | CAE | 35 min |
| Jul 8, 3:20 AM EDT | Severe Thunderstorm Warning | CAE | 25 min |
| Jul 9, 4:23 PM EDT | Special Weather Statement | CAE | 37 min |
| Jul 11, 8:28 PM EDT | Special Weather Statement | CAE | 32 min |
| Jul 15, 3:06 PM EDT | Special Weather Statement | CAE | 24 min |
| Jul 16, 4:39 PM EDT | Areal Flood Advisory | CAE | 2 hr |
| Jul 17, 2:43 PM EDT | Special Weather Statement | CAE | 47 min |
| Jul 17, 3:23 PM EDT | Severe Thunderstorm Warning | CAE | 67 min |
| Jul 18, 2:50 PM EDT | Severe Thunderstorm Warning | CAE | 25 min |
| Jul 27, 5:03 PM EDT | Special Weather Statement | CAE | 27 min |
| Jul 28, 7:14 PM EDT | Severe Thunderstorm Warning | CAE | 61 min |
| Jul 29, 2:44 PM EDT | Heat Advisory | CAE | 29 hr |
| Jul 31, 1:40 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 31, 8:12 PM EDT | Special Weather Statement | CAE | 33 min |
| Aug 3, 8:28 AM EDT | Areal Flood Advisory | CAE | 62 min |
| Aug 3, 9:32 AM EDT | Areal Flood Advisory | CAE | 118 min |
| Aug 3, 11:47 AM EDT | Areal Flood Advisory | CAE | 58 min |
| Aug 21, 3:48 PM EDT | Special Weather Statement | CAE | 42 min |
| Aug 23, 3:45 AM EDT | Dense Fog Advisory | CAE | 5 hr |
| Sep 15, 7:39 AM EDT | Dense Fog Advisory | CAE | 81 min |
| Sep 22, 2:44 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 22, 5:53 PM EDT | Severe Thunderstorm Warning | CAE | 52 min |
| Oct 16, 4:06 AM EDT | Lake Wind Advisory | CAE | 28 hr |
| Nov 5, 2:27 PM EDT | Lake Wind Advisory | CAE | 45 hr |
| Nov 13, 3:40 AM EST | Frost Advisory | CAE | 29 hr |
| Nov 15, 10:46 AM EST | Frost Advisory | CAE | 22 hr |
| Nov 19, 12:52 AM EST | Lake Wind Advisory | CAE | 10 hr |
| Nov 19, 3:39 AM EST | Frost Advisory | CAE | 28 hr |
| Nov 22, 2:26 AM EST | Freeze Watch | CAE | 25 hr |
| Nov 22, 4:20 PM EST | Lake Wind Advisory | CAE | 15 hr |
| Nov 23, 3:47 AM EST | Freeze Warning | CAE | 29 hr |
| Dec 5, 3:27 AM EST | Dense Fog Advisory | CAE | 7 hr |
| Dec 6, 1:33 AM EST | Dense Fog Advisory | CAE | 7 hr |
| Dec 8, 10:10 PM EST | Dense Fog Advisory | CAE | 11 hr |
| Dec 10, 7:35 PM EST | Dense Fog Advisory | CAE | 13 hr |
| Dec 16, 9:33 PM EST | Dense Fog Advisory | CAE | 12 hr |
| Dec 17, 9:36 PM EST | Dense Fog Advisory | CAE | 12 hr |
| Dec 19, 1:51 PM EST | Lake Wind Advisory | CAE | 8 hr |
| Dec 24, 8:18 PM EST | Lake Wind Advisory | CAE | 23 hr |
| Dec 27, 3:29 AM EST | Dense Fog Advisory | CAE | 7 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 | 15 |
| Severe Thunderstorm Watch | 2 |
| Tornado Watch | 1 |
| Mesoscale Discussion | 13 |
| Special Weather Statement | 9 |
| Flooding | |
| Flash Flood Watch | 3 |
| Areal Flood Advisory | 5 |
| Heat | |
| Heat Advisory | 1 |
| Cold | |
| Freeze Warning | 3 |
| Freeze Watch | 2 |
| Frost Advisory | 5 |
| Wind and dust | |
| Lake Wind Advisory | 14 |
| Fire | |
| Red Flag Warning | 1 |
| Fire Weather Watch | 1 |
| Fog and smoke | |
| Dense Fog Advisory | 16 |
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.