Weather alerts in South Dakota, 2010
1,736 weather alerts in 2010, 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 2010. Tap one for its archive.
- Alerts
- 1,736
- Warnings
- 1,072
- Watches
- 180
- Advisories
- 279
- Busiest month
- June415 alerts
- Busiest day
- May 24, 2010100 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
22 of 60 tornado warnings covering South Dakota in 2010 had a tornado report inside them; 36 of 45 tornado reports fell inside a warning, on average 20 minutes after it went out.
South Dakota, 2010
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 60 | 22 | 63% | 45 | 80% | 20 min |
| Severe thunderstorm warnings | 688 | 518 | 25% | 990 | 86% | 23 min |
| Flash flood warnings | 75 | 57 | 24% | 98 | 92% | 81 min |
Each office's whole area, 2010
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sioux Falls, SD: tornado warnings | 45 | 20 | 56% | 34 | 91% | 20 min |
| NWS Sioux Falls, SD: severe thunderstorm warnings | 320 | 241 | 25% | 508 | 87% | 20 min |
| NWS Sioux Falls, SD: flash flood warnings | 77 | 62 | 19% | 124 | 91% | 64 min |
| NWS Rapid City, SD: tornado warnings | 22 | 4 | 82% | 11 | 45% | 20 min |
| NWS Rapid City, SD: severe thunderstorm warnings | 323 | 259 | 20% | 520 | 90% | 27 min |
| NWS Rapid City, SD: flash flood warnings | 9 | 5 | 44% | 22 | 95% | 110 min |
| NWS Aberdeen, SD: tornado warnings | 18 | 9 | 50% | 24 | 79% | 19 min |
| NWS Aberdeen, SD: severe thunderstorm warnings | 214 | 143 | 33% | 296 | 80% | 20 min |
| NWS Aberdeen, SD: flash flood warnings | 18 | 10 | 44% | 16 | 81% | 111 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
1,736 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 County240
- Meade County211
- Minnehaha County204
- Charles Mix County201
- Aurora County200
- Custer County199
- Brule County195
- Hutchinson County194
- Lincoln County194
- Davison County188
- Turner County188
- Moody County187
- Brookings County184
- Douglas County179
- Gregory County179
- Hanson County179
- McCook County178
- Sanborn County178
- Hand County177
- Lyman County176
- Lake County173
- Bon Homme County172
- Miner County171
- Union County170
- Kingsbury County168
- Spink County167
- Codington County166
- Yankton County165
- Perkins County164
- Hamlin County164
- Brown County163
- Buffalo County163
- Beadle County159
- Hyde County158
- Jerauld County158
- Clark County157
- Hughes County157
- Ziebach County154
- Clay County154
- Tripp County152
26 more counties
- Stanley County151
- Jackson County151
- Butte County150
- Deuel County150
- Faulk County149
- Dewey County147
- Jones County147
- Fall River County145
- McPherson County143
- Haakon County142
- Potter County142
- Sully County142
- Harding County141
- Corson County141
- Day County141
- Mellette County141
- Grant County140
- Marshall County140
- Lawrence County140
- Edmunds County139
- Todd County139
- Roberts County138
- Campbell County132
- Bennett County132
- Walworth County130
- Oglala Lakota County84
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20092011
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.