Severe Thunderstorm Warnings in Colorado, 2009

By month

257 of 621 severe thunderstorm warnings covering Colorado in 2009 had a qualifying storm report inside them; 456 of 608 hail, wind and damage reports fell inside a warning, on average 21 minutes after it went out.

Colorado, 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.

• Weld County72
• Las Animas County67
• Yuma County60
• Kit Carson County48
• El Paso County48
• Elbert County47
• Washington County43
• Lincoln County43
• Pueblo County42
• Adams County41
• Arapahoe County41
• Logan County40
• Baca County38
• Bent County32
• Cheyenne County31
• Prowers County31
• Huerfano County30
• Kiowa County27
• Morgan County22
• Denver County22
• Sedgwick County20
• Otero County20
• Douglas County19
• Fremont County18
• Crowley County16
• Phillips County16
• Boulder County15
• Larimer County14
• Jefferson County13
• Custer County13
• Teller County12
• Moffat County10
• Broomfield County9
• Mesa County6
• Saguache County4
• Rio Blanco County3
• Routt County3
• Park County3
• Delta County2
• Garfield County2

1. August 18, 200938severe thunderstorm warnings
2. June 14, 200929severe thunderstorm warnings
3. July 21, 200923severe thunderstorm warnings
4. August 10, 200922severe thunderstorm warnings
5. July 12, 200921severe thunderstorm warnings
6. July 29, 200920severe thunderstorm warnings
7. June 13, 200915severe thunderstorm warnings
8. August 11, 200915severe thunderstorm warnings
9. July 13, 200913severe thunderstorm warnings
10. July 23, 200913severe thunderstorm warnings
11. August 17, 200913severe thunderstorm warnings
12. June 10, 200912severe thunderstorm 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.