Alert archive / South Carolina

Weather alerts in South Carolina, 2015

2,955 weather alerts in 2015, 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 2015. Tap one for its archive.

Alerts
2,955
Warnings
1,000
Watches
94
Advisories
765
Busiest month
June628 alerts
Busiest day
August 6, 201574 alerts

Over time

By month

Warning verification

How often warnings here had a storm report inside them, and how much warning the reports had.

6 of 12 tornado warnings covering South Carolina in 2015 had a tornado report inside them; 10 of 17 tornado reports fell inside a warning, on average 11 minutes after it went out.

South Carolina, 2015

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
Tornado warnings12650%1759%11 min
Severe thunderstorm warnings47636922%87484%24 min
Flash flood warnings917419%39993%297 min

Each office's whole area, 2015

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
NWS Columbia, SC: tornado warnings5340%560%12 min
NWS Columbia, SC: severe thunderstorm warnings18314023%30991%23 min
NWS Columbia, SC: flash flood warnings393023%11094%77 min
NWS Greenville-Spartanburg, SC: tornado warnings40100%20%
NWS Greenville-Spartanburg, SC: severe thunderstorm warnings26320721%51585%22 min
NWS Greenville-Spartanburg, SC: flash flood warnings634332%14476%131 min
NWS Charleston, SC: tornado warnings5340%1182%9 min
NWS Charleston, SC: severe thunderstorm warnings18013724%50379%23 min
NWS Charleston, SC: flash flood warnings211719%19296%473 min
NWS Wilmington, NC: tornado warnings6350%956%5 min
NWS Wilmington, NC: severe thunderstorm warnings895637%15372%22 min
NWS Wilmington, NC: flash flood warnings151220%7497%175 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

2,955 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.

6 more counties

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force nowTornadoes on recordThe radar archive20142016

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.