Alert archive / South Carolina
Weather alerts in South Carolina, 2011
2,956 weather alerts in 2011, 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 2011. Tap one for its archive.
- Alerts
- 2,956
- Warnings
- 1,155
- Watches
- 88
- Advisories
- 528
- Busiest month
- August542 alerts
- Busiest day
- May 27, 201176 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
18 of 50 tornado warnings covering South Carolina in 2011 had a tornado report inside them; 24 of 26 tornado reports fell inside a warning, on average 20 minutes after it went out.
South Carolina, 2011
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 50 | 18 | 64% | 26 | 92% | 20 min |
| Severe thunderstorm warnings | 935 | 697 | 25% | 1,516 | 90% | 28 min |
| Flash flood warnings | 25 | 9 | 64% | 19 | 74% | 33 min |
Each office's whole area, 2011
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Charleston, SC: tornado warnings | 9 | 2 | 78% | 10 | 90% | 21 min |
| NWS Charleston, SC: severe thunderstorm warnings | 299 | 217 | 27% | 591 | 89% | 26 min |
| NWS Charleston, SC: flash flood warnings | 10 | 4 | 60% | 22 | 86% | 47 min |
| NWS Greenville-Spartanburg, SC: tornado warnings | 42 | 11 | 74% | 25 | 96% | 21 min |
| NWS Greenville-Spartanburg, SC: severe thunderstorm warnings | 693 | 551 | 20% | 1,309 | 89% | 26 min |
| NWS Greenville-Spartanburg, SC: flash flood warnings | 31 | 20 | 35% | 46 | 85% | 105 min |
| NWS Columbia, SC: tornado warnings | 13 | 8 | 38% | 11 | 100% | 15 min |
| NWS Columbia, SC: severe thunderstorm warnings | 298 | 199 | 33% | 543 | 86% | 28 min |
| NWS Columbia, SC: flash flood warnings | 15 | 4 | 73% | 11 | 82% | 30 min |
| NWS Wilmington, NC: tornado warnings | 32 | 10 | 69% | 18 | 78% | 23 min |
| NWS Wilmington, NC: severe thunderstorm warnings | 166 | 123 | 26% | 383 | 83% | 28 min |
| NWS Wilmington, NC: flash flood warnings | 2 | 1 | 50% | 3 | 100% | 39 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
2,956 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.
- Berkeley County312
- Richland County275
- Lexington County249
- Laurens County249
- Calhoun County237
- York County236
- Colleton County233
- Kershaw County233
- Sumter County233
- Dorchester County233
- Chester County228
- Lee County226
- Florence County226
- Aiken County224
- Chesterfield County221
- Greenville County219
- Union County218
- Marion County218
- Anderson County217
- Horry County217
- Cherokee County211
- Fairfield County208
- Hampton County205
- Clarendon County204
- Spartanburg County203
- Dillon County202
- Williamsburg County200
- Abbeville County195
- Darlington County195
- Georgetown County191
- Bamberg County189
- Saluda County188
- Marlboro County188
- Greenwood County186
- Newberry County185
- Barnwell County184
- Edgefield County183
- Charleston County183
- Jasper County180
- Allendale County179
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe 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.