Alert archive / Maryland

Weather alerts in Baltimore County, Maryland

4,953 weather alerts since 1986, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

Baltimore County and its neighbors

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

Alerts
4,953
Warnings
1,788
Watches
878
Advisories
1,209
Busiest year
2011330 alerts
Average year
127over 39 years on file

Over time

By year

Before late 2005 the archive holds only tornado, severe thunderstorm, flash flood and marine warnings, and from 1997 SPC's watches, so the jump that year is the archive widening, not the weather.

By month of the year

Warning verification

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

From 2008 to 2025, 87% of tornado reports in Baltimore County fell inside a tornado warning issued on average 13 minutes before, and 80% of the tornado warnings had no report inside them.

Tornado warnings by year

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
200810100%0
200920100%20%
201030100%0
201111373%2100%10 min
201211282%0
20135260%3100%5 min
201430100%0
201520100%0
201610100%0
201810100%0
20194175%1100%8 min
202040100%0
202110370%1100%0 min
202250100%0
202310100%0
202411373%5100%25 min
20256267%1100%2 min
Share of tornado reports inside a tornado warning, by year.

Severe thunderstorm warnings by year

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
2008261542%2696%30 min
2009241442%1883%29 min
2010352626%2065%35 min
2011403220%3577%23 min
2012403513%5273%27 min
2013201430%1164%26 min
2014282318%3158%27 min
2015322328%2864%19 min
2016292031%2986%23 min
2017353014%5391%18 min
2018312423%1788%16 min
2019756119%4990%19 min
2020463720%3678%22 min
2021605017%9071%19 min
2022302517%3765%20 min
2023474211%5392%20 min
2024261638%1593%20 min
2025403318%4486%24 min

Flash flood warnings by year

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
20084325%967%88 min
20096350%5100%39 min
201012742%989%201 min
2011332136%4286%134 min
2012171418%2195%95 min
20139633%4100%46 min
20147357%875%106 min
2015251540%1958%42 min
20165260%4100%75 min
201710640%1060%37 min
201817853%1392%65 min
20195420%7100%83 min
2020141029%1486%60 min
20215420%1173%33 min
202211555%580%39 min
20239544%10100%56 min
202416756%6100%55 min
2025171229%21100%56 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.

By product

Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.

The latest warnings

The most recent on file, newest first.

IssuedProductOfficeLasted
Sep 3, 10:41 PM EDTSevere Thunderstorm WarningLWX35 min
Sep 2, 1:06 PM EDTSevere Thunderstorm WarningLWX39 min
Sep 2, 12:46 PM EDTSevere Thunderstorm WarningLWX44 min
Sep 2, 12:39 PM EDTSevere Thunderstorm WarningLWX51 min
Sep 2, 12:00 PM EDTSevere Thunderstorm WarningLWX45 min
Aug 27, 4:11 PM EDTSevere Thunderstorm WarningLWX34 min
Aug 10, 5:40 PM EDTFlash Flood WarningLWX88 min
Aug 10, 4:41 PM EDTSevere Thunderstorm WarningLWX31 min
Aug 10, 4:18 PM EDTTornado WarningLWX13 min
Aug 10, 4:14 PM EDTTornado WarningLWX18 min
Aug 10, 4:10 PM EDTSevere Thunderstorm Warning Destructive damage threatLWX35 min
Aug 10, 3:55 PM EDTSevere Thunderstorm Warning Considerable damage threatLWX50 min

Nearby

Alerts in force nowTornadoes on recordForecastThe 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.