Alert archive / South Carolina
Weather alerts in South Carolina, 2018
2,964 weather alerts in 2018, 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 2018. Tap one for its archive.
- Alerts
- 2,964
- Warnings
- 813
- Watches
- 92
- Advisories
- 646
- Busiest month
- June688 alerts
- Busiest day
- June 25, 201897 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
12 of 34 tornado warnings covering South Carolina in 2018 had a tornado report inside them; 15 of 21 tornado reports fell inside a warning, on average 8 minutes after it went out.
South Carolina, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 34 | 12 | 65% | 21 | 71% | 8 min |
| Severe thunderstorm warnings | 438 | 312 | 29% | 742 | 84% | 19 min |
| Flash flood warnings | 37 | 28 | 24% | 88 | 86% | 121 min |
Each office's whole area, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Greenville-Spartanburg, SC: tornado warnings | 7 | 1 | 86% | 3 | 67% | 5 min |
| NWS Greenville-Spartanburg, SC: severe thunderstorm warnings | 347 | 244 | 30% | 600 | 87% | 20 min |
| NWS Greenville-Spartanburg, SC: flash flood warnings | 74 | 53 | 28% | 177 | 83% | 159 min |
| NWS Wilmington, NC: tornado warnings | 37 | 14 | 62% | 22 | 73% | 12 min |
| NWS Wilmington, NC: severe thunderstorm warnings | 56 | 28 | 50% | 74 | 68% | 16 min |
| NWS Wilmington, NC: flash flood warnings | 30 | 19 | 37% | 199 | 90% | 391 min |
| NWS Charleston, SC: tornado warnings | 4 | 0 | 100% | 5 | 0% | |
| NWS Charleston, SC: severe thunderstorm warnings | 70 | 42 | 40% | 174 | 64% | 20 min |
| NWS Charleston, SC: flash flood warnings | 2 | 1 | 50% | 1 | 100% | 39 min |
| NWS Columbia, SC: tornado warnings | 10 | 4 | 60% | 11 | 73% | 8 min |
| NWS Columbia, SC: severe thunderstorm warnings | 174 | 130 | 25% | 327 | 87% | 18 min |
| NWS Columbia, SC: flash flood warnings | 14 | 11 | 21% | 46 | 100% | 149 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
2,964 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.
- Horry County226
- Richland County226
- Lexington County214
- York County197
- Greenville County185
- Georgetown County184
- Calhoun County183
- Kershaw County180
- Berkeley County175
- Spartanburg County171
- Cherokee County168
- Chesterfield County167
- Sumter County165
- Aiken County163
- Union County158
- Laurens County157
- Clarendon County152
- Chester County150
- Lee County148
- Florence County146
- Fairfield County145
- Anderson County145
- Oconee County145
- Newberry County142
- Pickens County134
- Colleton County132
- Saluda County131
- Dorchester County130
- Edgefield County128
- Barnwell County125
- Marion County124
- Greenwood County124
- Charleston County122
- Dillon County121
- Marlboro County120
- Williamsburg County119
- Abbeville County119
- Darlington County117
- Bamberg County112
- McCormick County110
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20172019
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.