Flash Flood Warnings in North Dakota, 2009

By month

8 of 29 flash flood warnings covering North Dakota in 2009 had a flash flood report inside them; 13 of 14 flash flood reports fell inside a warning, on average 198 minutes after it went out.

North Dakota, 2009

Each office's whole area, 2009

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.

• Burleigh County7
• Morton County4
• Nelson County4
• Emmons County3
• Cavalier County3
• Stutsman County2
• Cass County2
• Eddy County2
• Kidder County2
• Richland County2
• Pembina County2
• Towner County2
• Walsh County2
• Grand Forks County2
• Dickey County1
• LaMoure County1
• Griggs County1
• Ransom County1
• Bottineau County1
• Rolette County1
• Ward County1
• Sheridan County1
• Wells County1
• Benson County1
• Ramsey County1
• Traill County1
• Sioux County1
• McKenzie County1
• Williams County1

1. June 27, 20096flash flood warnings
2. March 27, 20094flash flood warnings
3. March 22, 20092flash flood warnings
4. March 25, 20092flash flood warnings
5. June 16, 20092flash flood warnings
6. June 18, 20092flash flood warnings
7. June 19, 20092flash flood warnings
8. June 26, 20092flash flood warnings
9. July 3, 20092flash flood warnings
10. September 11, 20092flash flood warnings
11. June 17, 20091flash flood warnings
12. August 14, 20091flash flood warnings

Alerts in force nowTornadoes on recordThe radar archive20082010

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.