Weather alerts in South Dakota, 2013
1,746 weather alerts in 2013, 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 2013. Tap one for its archive.
- Alerts
- 1,746
- Warnings
- 804
- Watches
- 112
- Advisories
- 273
- Busiest month
- August330 alerts
- Busiest day
- June 21, 201390 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
8 of 25 tornado warnings covering South Dakota in 2013 had a tornado report inside them; 15 of 21 tornado reports fell inside a warning, on average 17 minutes after it went out.
South Dakota, 2013
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 25 | 8 | 68% | 21 | 71% | 17 min |
| Severe thunderstorm warnings | 627 | 454 | 28% | 854 | 88% | 23 min |
| Flash flood warnings | 40 | 18 | 55% | 32 | 91% | 69 min |
Each office's whole area, 2013
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Rapid City, SD: tornado warnings | 10 | 1 | 90% | 3 | 33% | 4 min |
| NWS Rapid City, SD: severe thunderstorm warnings | 502 | 363 | 28% | 673 | 90% | 23 min |
| NWS Rapid City, SD: flash flood warnings | 24 | 5 | 79% | 14 | 93% | 46 min |
| NWS Aberdeen, SD: tornado warnings | 15 | 5 | 67% | 9 | 56% | 14 min |
| NWS Aberdeen, SD: severe thunderstorm warnings | 182 | 127 | 30% | 249 | 79% | 22 min |
| NWS Aberdeen, SD: flash flood warnings | 13 | 10 | 23% | 13 | 100% | 96 min |
| NWS Sioux Falls, SD: tornado warnings | 20 | 12 | 40% | 38 | 84% | 21 min |
| NWS Sioux Falls, SD: severe thunderstorm warnings | 123 | 86 | 30% | 169 | 87% | 21 min |
| NWS Sioux Falls, SD: flash flood warnings | 16 | 11 | 31% | 17 | 82% | 89 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
1,746 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.
- Pennington County335
- Custer County295
- Meade County290
- Lawrence County288
- Butte County232
- Perkins County190
- Harding County188
- Jackson County178
- Fall River County176
- Ziebach County164
- Haakon County157
- Dewey County154
- Bennett County153
- Spink County148
- Roberts County146
- Todd County145
- Mellette County143
- Corson County142
- Brown County136
- Day County136
- Edmunds County134
- McPherson County134
- Grant County134
- Marshall County134
- Codington County133
- Faulk County131
- Clark County130
- Hamlin County126
- Oglala Lakota County125
- Campbell County125
- Walworth County124
- Hand County121
- Potter County119
- Jones County114
- Stanley County114
- Deuel County114
- Tripp County109
- Lyman County107
- Sully County106
- Hughes County105
26 more counties
- Hyde County102
- Minnehaha County96
- Buffalo County95
- Charles Mix County90
- Beadle County90
- Brule County88
- Gregory County87
- Moody County86
- Brookings County85
- Lincoln County85
- Union County84
- Kingsbury County83
- Aurora County83
- Jerauld County83
- Sanborn County83
- Turner County82
- Douglas County82
- Yankton County81
- Miner County80
- Clay County79
- McCook County78
- Bon Homme County77
- Hutchinson County77
- Lake County76
- Davison County74
- Hanson County72
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20122014
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.