Alert archive / Iowa / Shelby County
Weather alerts in Shelby County, Iowa, 2020
84 weather alerts in 2020, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Shelby County and its neighbors
Each county as a circle sized by its count in 2020. Tap one for its archive.
- Alerts
- 84
- Warnings
- 10
- Watches
- 9
- Advisories
- 44
- Busiest month
- January13 alerts
- Busiest day
- May 24, 20208 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Shelby County, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 4 | 4 | 0% | 3 | 100% | 30 min |
| Flash flood warnings | 0 | 0 |
Each office's whole area, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Omaha, NE: tornado warnings | 7 | 1 | 86% | 3 | 67% | 6 min |
| NWS Omaha, NE: severe thunderstorm warnings | 209 | 126 | 40% | 318 | 84% | 23 min |
| NWS Omaha, NE: flash flood warnings | 15 | 10 | 33% | 22 | 73% | 65 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
Every alert, in the order issued. Times are local, Central Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jan 5, 3:35 AM CST | Wind Advisory | OAX | 9 hr |
| Jan 9, 9:27 PM CST | Winter Weather Advisory | OAX | 23 hr |
| Jan 13, 5:50 PM CST | Dense Fog Advisory | OAX | 14 hr |
| Jan 14, 2:01 PM CST | Winter Weather Advisory | OAX | 18 hr |
| Jan 16, 3:12 AM CST | Winter Weather Advisory | OAX | 51 hr |
| Jan 17, 6:32 AM CST | Mesoscale Discussion | SPC | 5 hr |
| Jan 18, 2:56 AM CST | Wind Advisory | OAX | 10 hr |
| Jan 18, 3:23 AM CST | Wind Chill Advisory | OAX | 33 hr |
| Jan 19, 2:32 PM CST | Wind Chill Advisory | OAX | 19 hr |
| Jan 21, 2:50 PM CST | Winter Weather Advisory | OAX | 27 hr |
| Jan 22, 2:52 PM CST | Dense Fog Advisory | OAX | 18 hr |
| Jan 26, 1:16 AM CST | Dense Fog Advisory | OAX | 11 hr |
| Jan 26, 6:02 PM CST | Dense Fog Advisory | OAX | 11 hr |
| Feb 12, 4:00 AM CST | Wind Chill Advisory | OAX | 32 hr |
| Mar 4, 1:46 PM CST | Wind Advisory | OAX | 28 hr |
| Mar 7, 3:11 AM CST | Red Flag Warning | OAX | 16 hr |
| Mar 12, 4:24 PM CDT | Winter Weather Advisory | OAX | 44 hr |
| Mar 18, 3:39 PM CDT | Winter Weather Advisory | OAX | 38 hr |
| Mar 27, 3:10 PM CDT | Wind Advisory | OAX | 33 hr |
| Mar 28, 3:06 PM CDT | Special Weather Statement | OAX | 24 min |
| Mar 28, 3:27 PM CDT | Special Weather Statement | OAX | 63 min |
| Apr 2, 3:34 AM CDT | Winter Weather Advisory | OAX | 33 hr |
| Apr 7, 6:55 AM CDT | Dense Fog Advisory | OAX | 3 hr |
| Apr 8, 3:32 PM CDT | Wind Advisory | OAX | 27 hr |
| Apr 10, 3:22 PM CDT | Winter Storm Watch | OAX | 24 hr |
| Apr 11, 3:14 PM CDT | Wind Advisory | OAX | 31 hr |
| Apr 15, 3:55 PM CDT | Winter Weather Advisory | OAX | 36 hr |
| Apr 28, 6:41 PM CDT | Special Weather Statement | OAX | 49 min |
| Apr 29, 2:35 AM CDT | Wind Advisory | OAX | 16 hr |
| May 5, 8:39 AM CDT | Wind Advisory | OAX | 9 hr |
| May 8, 2:54 AM CDT | Frost Advisory | OAX | 29 hr |
| May 10, 2:49 AM CDT | Freeze Warning | OAX | 28 hr |
| May 14, 5:47 AM CDT | Dense Fog Advisory | OAX | 3 hr |
| May 16, 6:45 PM CDT | Mesoscale Discussion | SPC | 90 min |
| May 23, 11:58 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| May 24, 4:13 AM CDT | Mesoscale Discussion | SPC | 62 min |
| May 24, 5:12 AM CDT | Severe Thunderstorm Warning | OAX | 33 min |
| May 24, 5:30 AM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| May 24, 5:38 AM CDT | Severe Thunderstorm Warning | OAX | 52 min |
| May 24, 1:13 PM CDT | Mesoscale Discussion | SPC | 92 min |
| May 24, 1:40 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| May 24, 3:25 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Jun 9, 3:22 AM CDT | Wind Advisory | OAX | 27 hr |
| Jun 18, 3:48 PM CDT | Mesoscale Discussion | SPC | 117 min |
| Jun 18, 6:30 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 21, 3:19 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 21, 6:59 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 28, 8:19 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Jun 30, 11:25 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 1, 1:48 AM CDT | Mesoscale Discussion | SPC | 87 min |
| Jul 11, 1:59 AM CDT | Special Weather Statement | OAX | 31 min |
| Jul 11, 2:14 AM CDT | Special Weather Statement | OAX | 31 min |
| Jul 14, 3:14 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 16, 2:43 AM CDT | Dense Fog Advisory | OAX | 5 hr |
| Jul 17, 3:30 AM CDT | Heat Advisory | OAX | 41 hr |
| Jul 24, 3:02 PM CDT | Heat Advisory | OAX | 29 hr |
| Aug 10, 8:40 AM CDT | Mesoscale Discussion | SPC | 65 min |
| Aug 10, 8:46 AM CDT | Severe Thunderstorm Warning | OAX | 29 min |
| Aug 10, 9:09 AM CDT | Severe Thunderstorm Warning | OAX | 51 min |
| Aug 14, 1:57 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 28, 2:56 PM CDT | Mesoscale Discussion | SPC | 64 min |
| Sep 2, 1:58 AM CDT | Dense Fog Advisory | OAX | 7 hr |
| Sep 13, 4:02 AM CDT | Dense Fog Advisory | OAX | 5 hr |
| Sep 23, 5:55 AM CDT | Dense Fog Advisory | OAX | 3 hr |
| Oct 1, 3:33 AM CDT | Frost Advisory | OAX | 28 hr |
| Oct 11, 3:05 PM CDT | Wind Advisory | OAX | 3 hr |
| Oct 11, 3:05 PM CDT | Wind Advisory | OAX | 10 hr |
| Oct 11, 3:52 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Oct 11, 4:54 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Oct 13, 3:15 PM CDT | Fire Weather Watch | OAX | 13 hr |
| Oct 13, 3:15 PM CDT | Red Flag Warning | OAX | 28 hr |
| Oct 15, 3:36 AM CDT | Freeze Warning | OAX | 30 hr |
| Oct 23, 3:53 PM CDT | Winter Weather Advisory | OAX | 69 hr |
| Nov 7, 2:39 PM CST | Wind Advisory | OAX | 27 hr |
| Nov 9, 3:15 PM CST | Winter Weather Advisory | OAX | 24 hr |
| Dec 10, 2:10 PM CST | Winter Weather Advisory | OAX | 44 hr |
| Dec 17, 5:07 PM CST | Dense Fog Advisory | OAX | 6 hr |
| Dec 22, 1:02 PM CST | Wind Advisory | OAX | 32 hr |
| Dec 22, 1:02 PM CST | Winter Weather Advisory | OAX | 10 hr |
| Dec 22, 10:51 PM CST | Winter Storm Warning | OAX | 22 hr |
| Dec 27, 3:05 PM CST | Winter Storm Watch | OAX | 12 hr |
| Dec 28, 3:34 AM CST | Winter Weather Advisory | OAX | 44 hr |
| Dec 28, 3:43 PM CST | Winter Storm Warning | OAX | 27 hr |
| Dec 29, 10:02 AM CST | Mesoscale Discussion | SPC | 5 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
| Product | Alerts |
|---|---|
| Severe storms | |
| Severe Thunderstorm Warning | 4 |
| Severe Thunderstorm Watch | 6 |
| Mesoscale Discussion | 16 |
| Special Weather Statement | 5 |
| Winter | |
| Winter Storm Warning | 2 |
| Winter Storm Watch | 2 |
| Winter Weather Advisory | 13 |
| Heat | |
| Heat Advisory | 2 |
| Cold | |
| Freeze Warning | 2 |
| Frost Advisory | 2 |
| Wind Chill Advisory | 3 |
| Wind and dust | |
| Wind Advisory | 13 |
| Fire | |
| Red Flag Warning | 2 |
| Fire Weather Watch | 1 |
| Fog and smoke | |
| Dense Fog Advisory | 11 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20192021
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.