Flash Flood Warnings in Maryland, 2010

By month

20 of 34 flash flood warnings covering Maryland in 2010 had a flash flood report inside them; 43 of 48 flash flood reports fell inside a warning, on average 174 minutes after it went out.

Maryland, 2010

Each office's whole area, 2010

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.

• Baltimore County12
• Montgomery County12
• Howard County11
• City of Baltimore11
• Carroll County10
• Anne Arundel County10
• Frederick County8
• Harford County7
• Calvert County7
• Prince George's County7
• Washington County6
• Saint Mary's County6
• Charles County4
• Allegany County3
• Cecil County1

1. September 30, 20108flash flood warnings
2. August 13, 20105flash flood warnings
3. October 1, 20103flash flood warnings
4. May 28, 20102flash flood warnings
5. July 14, 20102flash flood warnings
6. July 29, 20102flash flood warnings
7. August 12, 20102flash flood warnings
8. September 27, 20102flash flood warnings
9. December 1, 20102flash flood warnings
10. March 23, 20101flash flood warnings
11. March 29, 20101flash flood warnings
12. April 25, 20101flash flood warnings

Alerts in force nowTornadoes on recordThe radar archive20092011

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.