Alert archive / South Carolina
Weather alerts in South Carolina, 2017
2,850 weather alerts in 2017, 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 2017. Tap one for its archive.
- Alerts
- 2,850
- Warnings
- 894
- Watches
- 77
- Advisories
- 611
- Busiest month
- July650 alerts
- Busiest day
- April 5, 201788 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
25 of 70 tornado warnings covering South Carolina in 2017 had a tornado report inside them; 59 of 71 tornado reports fell inside a warning, on average 12 minutes after it went out.
South Carolina, 2017
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 70 | 25 | 64% | 71 | 83% | 12 min |
| Severe thunderstorm warnings | 448 | 310 | 31% | 794 | 78% | 21 min |
| Flash flood warnings | 38 | 21 | 45% | 49 | 96% | 55 min |
Each office's whole area, 2017
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Columbia, SC: tornado warnings | 29 | 12 | 59% | 33 | 85% | 11 min |
| NWS Columbia, SC: severe thunderstorm warnings | 205 | 135 | 34% | 331 | 85% | 23 min |
| NWS Columbia, SC: flash flood warnings | 19 | 13 | 32% | 40 | 93% | 36 min |
| NWS Charleston, SC: tornado warnings | 35 | 10 | 71% | 25 | 64% | 9 min |
| NWS Charleston, SC: severe thunderstorm warnings | 102 | 64 | 37% | 213 | 67% | 21 min |
| NWS Charleston, SC: flash flood warnings | 10 | 5 | 50% | 6 | 100% | 247 min |
| NWS Wilmington, NC: tornado warnings | 19 | 1 | 95% | 6 | 17% | 7 min |
| NWS Wilmington, NC: severe thunderstorm warnings | 87 | 49 | 44% | 121 | 65% | 18 min |
| NWS Wilmington, NC: flash flood warnings | 9 | 3 | 67% | 8 | 88% | 49 min |
| NWS Greenville-Spartanburg, SC: tornado warnings | 35 | 12 | 66% | 46 | 93% | 19 min |
| NWS Greenville-Spartanburg, SC: severe thunderstorm warnings | 286 | 227 | 21% | 736 | 76% | 20 min |
| NWS Greenville-Spartanburg, SC: flash flood warnings | 23 | 14 | 39% | 50 | 64% | 48 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
2,850 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.
- Lexington County211
- Richland County204
- Aiken County187
- Horry County184
- Berkeley County181
- Greenville County180
- Calhoun County173
- Clarendon County168
- Kershaw County158
- Anderson County157
- Sumter County150
- Orangeburg County144
- Spartanburg County143
- Charleston County142
- Dorchester County142
- Bamberg County141
- Marion County141
- Cherokee County141
- Barnwell County140
- Edgefield County140
- McCormick County140
- Florence County139
- Saluda County138
- Chesterfield County137
- Pickens County137
- York County136
- Laurens County135
- Williamsburg County135
- Colleton County134
- Lee County133
- Union County132
- Georgetown County131
- Dillon County129
- Newberry County129
- Fairfield County128
- Abbeville County126
- Chester County126
- Darlington County124
- Oconee County124
- Greenwood County123
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20162018
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.