Alert archive / Missouri / Jefferson County
Weather alerts in Jefferson County, Missouri, 2020
113 weather alerts in 2020, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Jefferson County and its neighbors
Each county as a circle sized by its count in 2020. Tap one for its archive.
- Alerts
- 113
- Warnings
- 44
- Watches
- 22
- Advisories
- 29
- Busiest month
- January21 alerts
- Busiest day
- January 10, 20206 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Jefferson County, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 11 | 6 | 45% | 7 | 71% | 26 min |
| Flash flood warnings | 4 | 1 | 75% | 2 | 100% | 63 min |
Each office's whole area, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS St. Louis, MO: tornado warnings | 10 | 2 | 80% | 12 | 17% | 5 min |
| NWS St. Louis, MO: severe thunderstorm warnings | 157 | 69 | 56% | 280 | 79% | 24 min |
| NWS St. Louis, MO: flash flood warnings | 64 | 34 | 47% | 88 | 86% | 74 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 8, 2:31 PM CST | Flash Flood Watch | LSX | 61 hr |
| Jan 10, 3:58 AM CST | Winter Weather Advisory | LSX | 41 hr |
| Jan 10, 10:11 AM CST | River Flood Warning | LSX | 4 days |
| Jan 10, 10:11 AM CST | River Flood Warning | LSX | 5 days |
| Jan 10, 10:11 AM CST | River Flood Warning | LSX | 5 days |
| Jan 10, 10:11 AM CST | River Flood Warning | LSX | 7 days |
| Jan 10, 10:11 AM CST | River Flood Warning | LSX | 6 days |
| Jan 10, 10:49 PM CST | Areal Flood Warning | LSX | 15 hr |
| Jan 11, 2:28 AM CST | Areal Flood Advisory | LSX | 11 hr |
| Jan 11, 12:29 PM CST | Areal Flood Warning | LSX | 23 hr |
| Jan 11, 1:43 PM CST | Areal Flood Warning | LSX | 22 hr |
| Jan 11, 9:19 PM CST | River Flood Warning | LSX | 5 days |
| Jan 16, 2:57 PM CST | Flood Watch | LSX | 39 hr |
| Jan 16, 2:57 PM CST | Winter Weather Advisory | LSX | 33 hr |
| Jan 17, 9:45 AM CST | Mesoscale Discussion | SPC | 6 hr |
| Jan 18, 1:28 PM CST | River Flood Warning | LSX | 45 hr |
| Jan 18, 9:49 PM CST | River Flood Warning | LSX | 23 hr |
| Jan 19, 9:06 PM CST | River Flood Warning | LSX | 38 hr |
| Jan 21, 3:15 PM CST | Winter Weather Advisory | LSX | 3 days |
| Jan 26, 3:09 PM CST | Dense Fog Advisory | LSX | 21 hr |
| Jan 28, 3:26 AM CST | Winter Weather Advisory | LSX | 34 hr |
| Feb 4, 3:33 AM CST | Winter Storm Watch | LSX | 11 hr |
| Feb 4, 3:33 AM CST | Winter Weather Advisory | LSX | 20 hr |
| Feb 4, 2:46 PM CST | Winter Storm Warning | LSX | 24 hr |
| Feb 4, 2:46 PM CST | Winter Weather Advisory | LSX | 45 hr |
| Feb 24, 3:29 PM CST | Winter Weather Advisory | LSX | 44 hr |
| Mar 8, 3:25 AM CDT | Red Flag Warning | LSX | 16 hr |
| Mar 12, 6:05 AM CDT | Dense Fog Advisory | LSX | 4 hr |
| Mar 12, 9:21 AM CDT | Mesoscale Discussion | SPC | 114 min |
| Mar 18, 8:42 PM CDT | River Flood Warning | LSX | 24 days |
| Mar 19, 3:43 AM CDT | Flash Flood Watch | LSX | 21 hr |
| Mar 19, 8:35 PM CDT | River Flood Warning | LSX | 4 days |
| Mar 20, 10:51 AM CDT | River Flood Warning | LSX | 10 hr |
| Mar 26, 8:57 PM CDT | River Flood Warning | LSX | 23 hr |
| Mar 26, 10:27 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Mar 27, 5:15 PM CDT | Mesoscale Discussion | SPC | 90 min |
| Mar 28, 12:45 PM CDT | Severe Thunderstorm Warning | LSX | 21 min |
| Mar 28, 1:17 PM CDT | Mesoscale Discussion | SPC | 88 min |
| Mar 28, 3:53 PM CDT | Tornado Watch | SPC | 5 hr |
| Apr 8, 1:46 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Apr 8, 3:08 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Apr 8, 7:13 PM CDT | Severe Thunderstorm Warning | LSX | 14 min |
| Apr 12, 3:15 AM CDT | Wind Advisory | LSX | 31 hr |
| Apr 17, 11:46 AM CDT | Frost Advisory | LSX | 20 hr |
| Apr 24, 3:06 AM CDT | Dense Fog Advisory | LSX | 6 hr |
| Apr 25, 1:43 PM CDT | River Flood Warning | LSX | 11 hr |
| Apr 25, 8:52 PM CDT | River Flood Warning | LSX | 8 days |
| Apr 26, 5:31 AM CDT | River Flood Warning | LSX | 4 days |
| Apr 28, 3:33 PM CDT | Mesoscale Discussion | SPC | 87 min |
| Apr 28, 3:51 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Apr 28, 6:32 PM CDT | Mesoscale Discussion | SPC | 118 min |
| Apr 28, 9:06 PM CDT | Mesoscale Discussion | SPC | 84 min |
| May 8, 3:32 AM CDT | Frost Advisory | LSX | 28 hr |
| May 10, 2:43 PM CDT | Frost Advisory | LSX | 17 hr |
| May 15, 1:06 AM CDT | Mesoscale Discussion | SPC | 114 min |
| May 15, 1:40 AM CDT | Severe Thunderstorm Watch | SPC | 3 hr |
| May 15, 3:20 AM CDT | Mesoscale Discussion | SPC | 85 min |
| May 15, 4:33 AM CDT | Mesoscale Discussion | SPC | 57 min |
| May 16, 7:50 PM CDT | Areal Flood Advisory | LSX | 3 hr |
| May 16, 8:58 PM CDT | Flash Flood Watch | LSX | 21 hr |
| May 16, 9:19 PM CDT | River Flood Warning | LSX | 7 days |
| May 24, 5:13 PM CDT | Flash Flood Warning | LSX | 4 hr |
| May 24, 8:54 PM CDT | Flash Flood Warning | LSX | 6 hr |
| May 25, 6:16 AM CDT | River Flood Warning | LSX | 4 hr |
| May 26, 10:12 AM CDT | River Flood Warning | LSX | 20 days |
| May 28, 5:28 PM CDT | Severe Thunderstorm Warning | LSX | 32 min |
| Jun 3, 1:45 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 3, 3:52 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 21, 5:28 AM CDT | Flash Flood Warning | LSX | 4 hr |
| Jun 29, 3:09 AM CDT | Flash Flood Watch | LSX | 58 hr |
| Jun 30, 2:33 AM CDT | Areal Flood Advisory | LSX | 3 hr |
| Jul 8, 3:27 AM CDT | Heat Advisory | LSX | 40 hr |
| Jul 8, 4:17 PM CDT | Severe Thunderstorm Warning | LSX | 28 min |
| Jul 15, 1:10 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 15, 2:10 PM CDT | Tornado Watch | SPC | 7 hr |
| Jul 15, 4:11 PM CDT | Severe Thunderstorm Warning | LSX | 34 min |
| Jul 15, 5:35 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Jul 17, 1:59 AM CDT | Heat Advisory | LSX | 65 hr |
| Jul 19, 4:35 PM CDT | Flash Flood Watch | LSX | 8 hr |
| Jul 19, 7:32 PM CDT | Severe Thunderstorm Warning | LSX | 43 min |
| Jul 21, 1:11 AM CDT | Areal Flood Advisory | LSX | 5 hr |
| Jul 21, 1:32 AM CDT | Severe Thunderstorm Warning | LSX | 28 min |
| Jul 21, 2:12 AM CDT | Severe Thunderstorm Warning | LSX | 19 min |
| Jul 21, 6:18 PM CDT | Severe Thunderstorm Warning | LSX | 26 min |
| Jul 24, 11:43 AM CDT | Heat Advisory | LSX | 56 hr |
| Jul 29, 2:35 PM CDT | Flash Flood Watch | LSX | 33 hr |
| Jul 31, 3:25 AM CDT | Flash Flood Watch | LSX | 21 hr |
| Aug 8, 2:18 PM CDT | Flash Flood Watch | LSX | 20 hr |
| Aug 9, 2:41 AM CDT | Flash Flood Warning | LSX | 6 hr |
| Aug 9, 1:54 PM CDT | Heat Advisory | LSX | 29 hr |
| Aug 10, 2:38 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 10, 2:58 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 10, 5:16 PM CDT | Severe Thunderstorm Warning | LSX | 59 min |
| Aug 10, 5:17 PM CDT | Mesoscale Discussion | SPC | 118 min |
| Aug 10, 5:59 PM CDT | Severe Thunderstorm Warning | LSX | 61 min |
| Aug 10, 6:24 PM CDT | Areal Flood Advisory | LSX | 3 hr |
| Aug 13, 9:49 AM CDT | Flash Flood Watch | LSX | 9 hr |
| Aug 15, 2:00 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 31, 10:50 AM CDT | Severe Thunderstorm Watch | SPC | 3 hr |
| Aug 31, 11:04 AM CDT | Mesoscale Discussion | SPC | 86 min |
| Sep 3, 3:15 AM CDT | Dense Fog Advisory | LSX | 6 hr |
| Oct 4, 3:08 AM CDT | Frost Advisory | LSX | 29 hr |
| Oct 13, 2:42 PM CDT | Fire Weather Watch | LSX | 13 hr |
| Oct 14, 4:01 AM CDT | Red Flag Warning | LSX | 14 hr |
| Oct 15, 3:35 AM CDT | Frost Advisory | LSX | 29 hr |
| Oct 15, 2:08 PM CDT | Freeze Warning | LSX | 19 hr |
| Oct 16, 4:45 AM CDT | Fire Weather Watch | LSX | 10 hr |
| Oct 16, 2:34 PM CDT | Red Flag Warning | LSX | 27 hr |
| Nov 14, 3:12 AM CST | Wind Advisory | LSX | 36 hr |
| Nov 18, 2:35 PM CST | Wind Advisory | LSX | 27 hr |
| Nov 19, 3:25 AM CST | Red Flag Warning | LSX | 14 hr |
| Nov 22, 8:26 PM CST | River Flood Warning | LSX | 24 hr |
| Dec 23, 3:15 AM CST | Wind Advisory | LSX | 21 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 | 11 |
| Severe Thunderstorm Watch | 7 |
| Tornado Watch | 2 |
| Mesoscale Discussion | 18 |
| Flooding | |
| Areal Flood Warning | 3 |
| Flash Flood Warning | 4 |
| River Flood Warning | 20 |
| Flash Flood Watch | 9 |
| Flood Watch | 1 |
| Areal Flood Advisory | 5 |
| Winter | |
| Winter Storm Warning | 1 |
| Winter Storm Watch | 1 |
| Winter Weather Advisory | 7 |
| Heat | |
| Heat Advisory | 4 |
| Cold | |
| Freeze Warning | 1 |
| Frost Advisory | 5 |
| Wind and dust | |
| Wind Advisory | 4 |
| Fire | |
| Red Flag Warning | 4 |
| Fire Weather Watch | 2 |
| Fog and smoke | |
| Dense Fog Advisory | 4 |
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.