Alert archive / South Carolina
Weather alerts in South Carolina, 2020
3,225 weather alerts in 2020, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered any part of the state, so the counties below add up to more than the state.
Weather alerts by county
Each county as a circle sized by its count in 2020. Tap one for its archive.
- Alerts
- 3,225
- Warnings
- 922
- Watches
- 102
- Advisories
- 743
- Busiest month
- August497 alerts
- Busiest day
- February 6, 202097 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
34 of 102 tornado warnings covering South Carolina in 2020 had a tornado report inside them; 47 of 69 tornado reports fell inside a warning, on average 12 minutes after it went out.
South Carolina, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 102 | 34 | 67% | 69 | 68% | 12 min |
| Severe thunderstorm warnings | 420 | 244 | 42% | 792 | 77% | 23 min |
| Flash flood warnings | 44 | 31 | 30% | 105 | 78% | 99 min |
Each office's whole area, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Columbia, SC: tornado warnings | 28 | 15 | 46% | 25 | 80% | 14 min |
| NWS Columbia, SC: severe thunderstorm warnings | 155 | 89 | 43% | 321 | 82% | 23 min |
| NWS Columbia, SC: flash flood warnings | 20 | 17 | 15% | 74 | 86% | 66 min |
| NWS Charleston, SC: tornado warnings | 20 | 10 | 50% | 19 | 89% | 12 min |
| NWS Charleston, SC: severe thunderstorm warnings | 72 | 50 | 31% | 301 | 69% | 27 min |
| NWS Greenville-Spartanburg, SC: tornado warnings | 61 | 13 | 79% | 25 | 72% | 14 min |
| NWS Greenville-Spartanburg, SC: severe thunderstorm warnings | 325 | 183 | 44% | 520 | 75% | 21 min |
| NWS Greenville-Spartanburg, SC: flash flood warnings | 79 | 42 | 47% | 138 | 71% | 121 min |
| NWS Wilmington, NC: tornado warnings | 43 | 16 | 63% | 41 | 73% | 10 min |
| NWS Wilmington, NC: severe thunderstorm warnings | 65 | 34 | 48% | 92 | 87% | 21 min |
| NWS Wilmington, NC: flash flood warnings | 10 | 8 | 20% | 30 | 83% | 82 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
3,225 alerts are too many to list on one page. Narrow it to a product above, to a month in the chart, or to a county.
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Richland County274
- Lexington County248
- Horry County247
- York County199
- Calhoun County198
- Georgetown County194
- Greenville County190
- Kershaw County189
- Spartanburg County189
- Laurens County177
- Florence County175
- Chesterfield County172
- Lancaster County172
- Union County170
- Chester County170
- Marion County170
- Sumter County169
- Berkeley County169
- Cherokee County167
- Fairfield County158
- Clarendon County156
- Greenwood County152
- Anderson County151
- Newberry County151
- Dillon County147
- Lee County144
- Darlington County143
- Aiken County141
- Saluda County138
- Edgefield County136
- Marlboro County136
- Williamsburg County135
- Abbeville County134
- Oconee County132
- McCormick County127
- Pickens County126
- Bamberg County108
- Barnwell County107
- Dorchester County105
- Charleston County103
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe 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.