Flash Flood Warnings in Maryland, 2020

By month

37 of 60 flash flood warnings covering Maryland in 2020 had a flash flood report inside them; 113 of 123 flash flood reports fell inside a warning, on average 83 minutes after it went out.

Maryland, 2020

Each office's whole area, 2020

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.

• Prince George's County15
• Baltimore County14
• Montgomery County8
• Cecil County7
• City of Baltimore7
• Kent County7
• Queen Anne's County7
• Charles County6
• Saint Mary's County6
• Caroline County5
• Anne Arundel County5
• Harford County4
• Calvert County4
• Howard County3
• Worcester County3
• Somerset County3
• Talbot County2
• Wicomico County2
• Frederick County1
• Dorchester County1

1. August 4, 20209flash flood warnings
2. August 12, 20208flash flood warnings
3. July 7, 20207flash flood warnings
4. September 10, 20206flash flood warnings
5. July 24, 20204flash flood warnings
6. August 7, 20203flash flood warnings
7. August 8, 20203flash flood warnings
8. August 13, 20203flash flood warnings
9. August 29, 20203flash flood warnings
10. June 22, 20202flash flood warnings
11. July 10, 20202flash flood warnings
12. June 5, 20201flash flood warnings

Alerts in force nowTornadoes on recordThe radar archive20192021

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.