Severe Thunderstorm Warnings in Louisa County, Iowa

376 severe thunderstorm warnings since 1986. An alert counts here when it covered this county. The archive of severe thunderstorm warnings reaches back to 1986.

Louisa County and its neighbors

Each county as a circle sized by its count since 1986. Tap one for its archive.

Severe Thunderstorm Warnings: 376
Busiest year: 202436 severe thunderstorm warnings
Average year: 9over 40 years on file

Over time

By year

Before October 2007 these were issued for whole counties, and a storm crossing three counties was often three warnings; since then one polygon follows the storm. The count changed with the practice, not only with the weather.

Warning verification

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

From 2008 to 2025, 70% of hail, wind and damage reports in Louisa County fell inside a severe thunderstorm warning issued on average 23 minutes before, and 34% of the severe thunderstorm warnings had no report inside them.

Severe thunderstorm warnings by year

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
2008	20	8	60%	3	67%	25 min
2009	13	11	15%	1	0%
2010	19	9	53%	1	0%
2011	13	12	8%	1	100%	32 min
2012	14	10	29%	1	100%	3 min
2013	15	10	33%	5	100%	17 min
2014	12	8	33%	3	100%	21 min
2015	14	8	43%	1	100%	10 min
2016	6	6	0%	7	86%	34 min
2017	12	9	25%	10	50%	34 min
2018	9	8	11%	3	33%	6 min
2019	15	12	20%	2	100%	20 min
2020	12	11	8%	3	100%	13 min
2021	9	5	44%	4	100%	30 min
2022	12	4	67%	0
2023	21	14	33%	1	100%	6 min
2024	36	24	33%	8	38%	17 min
2025	14	7	50%	2	50%	34 min

Years from 2008, the first full year of storm-based warnings. The year still running is on its own page.

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 latest severe thunderstorm warnings

The most recent on file, newest first.

Issued	Product	Office	Lasted
Sep 20, 1:18 AM CDT	Severe Thunderstorm Warning	DVN	57 min
Aug 13, 9:36 AM CDT	Severe Thunderstorm Warning	DVN	54 min
Jul 20, 11:52 AM CDT	Severe Thunderstorm Warning	DVN	53 min
Jun 17, 7:57 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	63 min
Jun 17, 7:17 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	58 min
Jun 17, 7:08 AM CDT	Severe Thunderstorm Warning Destructive damage threat	DVN	52 min
Jun 17, 5:52 AM CDT	Severe Thunderstorm Warning	DVN	53 min
Jun 11, 9:20 AM CDT	Severe Thunderstorm Warning	DVN	54 min
Jun 11, 9:18 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	52 min
Jun 11, 8:19 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	71 min
Jun 10, 5:53 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	52 min
Jun 10, 5:19 PM CDT	Severe Thunderstorm Warning	DVN	56 min

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive

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.