Alert archive / Colorado / Arapahoe County
Weather alerts in Arapahoe County, Colorado, 2012
115 weather alerts in 2012, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Arapahoe County and its neighbors
Each county as a circle sized by its count in 2012. Tap one for its archive.
- Alerts
- 115
- Warnings
- 60
- Watches
- 20
- Advisories
- 16
- Busiest month
- June48 alerts
- Busiest day
- June 7, 201225 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
1 of 5 tornado warnings covering Arapahoe County in 2012 had a tornado report inside them; 1 of 2 tornado reports fell inside a warning, on average 15 minutes after it went out.
Arapahoe County, 2012
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 5 | 1 | 80% | 2 | 50% | 15 min |
| Severe thunderstorm warnings | 23 | 11 | 52% | 19 | 74% | 15 min |
| Flash flood warnings | 3 | 1 | 67% | 1 | 100% | 102 min |
Each office's whole area, 2012
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Denver/Boulder, CO: tornado warnings | 24 | 7 | 71% | 17 | 47% | 23 min |
| NWS Denver/Boulder, CO: severe thunderstorm warnings | 95 | 39 | 59% | 128 | 58% | 20 min |
| NWS Denver/Boulder, CO: flash flood warnings | 26 | 7 | 73% | 12 | 50% | 62 min |
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.
The alerts
Every alert, in the order issued. Times are local, Mountain Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Feb 1, 4:09 AM MST | Winter Storm Watch | BOU | 25 hr |
| Feb 2, 5:07 AM MST | Blizzard Warning | BOU | 35 hr |
| Feb 2, 5:07 AM MST | Winter Storm Warning | BOU | 47 hr |
| Feb 2, 5:08 PM MST | Mesoscale Discussion | SPC | 4 hr |
| Feb 3, 2:45 AM MST | Mesoscale Discussion | SPC | 4 hr |
| Feb 4, 3:55 AM MST | Winter Weather Advisory | BOU | 7 hr |
| Feb 19, 11:46 AM MST | Winter Weather Advisory | BOU | 23 hr |
| Feb 23, 4:37 AM MST | Winter Weather Advisory | BOU | 6 hr |
| Feb 29, 3:12 PM MST | Winter Weather Advisory | BOU | 38 hr |
| Mar 5, 3:40 PM MST | Fire Weather Watch | BOU | 8 hr |
| Mar 5, 11:39 PM MST | Red Flag Warning | BOU | 18 hr |
| Mar 16, 4:10 AM MDT | Fire Weather Watch | BOU | 11 hr |
| Mar 16, 3:07 PM MDT | Red Flag Warning | BOU | 29 hr |
| Mar 17, 7:38 PM MDT | Red Flag Warning | BOU | 26 hr |
| Mar 18, 3:10 AM MDT | High Wind Warning | BOU | 16 hr |
| Mar 24, 2:09 PM MDT | Fire Weather Watch | BOU | 22 hr |
| Mar 25, 12:15 PM MDT | Red Flag Warning | BOU | 33 hr |
| Mar 30, 4:16 PM MDT | Fire Weather Watch | BOU | 24 hr |
| Mar 30, 4:16 PM MDT | Red Flag Warning | BOU | 28 hr |
| Mar 31, 4:14 PM MDT | Red Flag Warning | BOU | 27 hr |
| Apr 1, 2:18 PM MDT | High Wind Warning | BOU | 22 hr |
| Apr 2, 4:38 AM MDT | Winter Storm Watch | BOU | 11 hr |
| Apr 2, 3:34 PM MDT | Winter Storm Warning | BOU | 26 hr |
| Apr 5, 4:05 AM MDT | Fire Weather Watch | BOU | 12 hr |
| Apr 5, 3:38 PM MDT | Red Flag Warning | BOU | 28 hr |
| Apr 11, 4:44 PM MDT | Severe Thunderstorm Warning | BOU | 27 min |
| Apr 11, 5:06 PM MDT | Tornado Warning | BOU | 24 min |
| Apr 26, 2:47 PM MDT | Mesoscale Discussion | SPC | 58 min |
| Apr 26, 8:41 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| May 5, 9:56 PM MDT | Severe Thunderstorm Warning | BOU | 49 min |
| May 5, 10:39 PM MDT | Severe Thunderstorm Warning | BOU | 51 min |
| May 12, 5:02 AM MDT | Dense Fog Advisory | BOU | 4 hr |
| May 17, 2:36 PM MDT | Fire Weather Watch | BOU | 13 hr |
| May 18, 4:05 AM MDT | Red Flag Warning | BOU | 16 hr |
| May 25, 4:01 AM MDT | High Wind Watch | BOU | 23 hr |
| May 26, 2:39 AM MDT | High Wind Warning | BOU | 17 hr |
| Jun 2, 2:20 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| Jun 2, 2:33 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 2, 2:35 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| Jun 2, 2:42 PM MDT | Severe Thunderstorm Warning | BOU | 31 min |
| Jun 2, 2:50 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| Jun 2, 3:03 PM MDT | Severe Thunderstorm Warning | BOU | 42 min |
| Jun 3, 1:03 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 6, 12:54 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 6, 3:01 PM MDT | Tornado Watch | SPC | 8 hr |
| Jun 6, 5:25 PM MDT | Severe Thunderstorm Warning | BOU | 50 min |
| Jun 6, 6:21 PM MDT | Severe Thunderstorm Warning | BOU | 54 min |
| Jun 6, 6:30 PM MDT | Areal Flood Advisory | BOU | 90 min |
| Jun 6, 6:35 PM MDT | Tornado Warning | BOU | 40 min |
| Jun 6, 6:47 PM MDT | Mesoscale Discussion | SPC | 58 min |
| Jun 6, 7:16 PM MDT | Flash Flood Warning | BOU | 3 hr |
| Jun 6, 7:16 PM MDT | Severe Thunderstorm Warning | BOU | 44 min |
| Jun 6, 7:44 PM MDT | Tornado Warning | BOU | 31 min |
| Jun 6, 8:37 PM MDT | Mesoscale Discussion | SPC | 23 min |
| Jun 6, 9:00 PM MDT | Severe Thunderstorm Warning | BOU | 45 min |
| Jun 6, 10:25 PM MDT | Flash Flood Warning | BOU | 3 hr |
| Jun 6, 11:02 PM MDT | Severe Thunderstorm Warning | BOU | 43 min |
| Jun 7, 12:16 AM MDT | Severe Thunderstorm Warning | BOU | 44 min |
| Jun 7, 12:30 AM MDT | Areal Flood Advisory | BOU | 90 min |
| Jun 7, 12:52 AM MDT | Flash Flood Warning | BOU | 3 hr |
| Jun 7, 12:56 AM MDT | Severe Thunderstorm Warning | BOU | 33 min |
| Jun 7, 1:39 AM MDT | Areal Flood Warning | BOU | 7 hr |
| Jun 7, 8:43 AM MDT | Areal Flood Advisory | BOU | 4 hr |
| Jun 7, 10:47 AM MDT | Flash Flood Watch | BOU | 13 hr |
| Jun 7, 11:46 AM MDT | Tornado Watch | SPC | 10 hr |
| Jun 7, 1:59 PM MDT | Mesoscale Discussion | SPC | 91 min |
| Jun 7, 4:51 PM MDT | Severe Thunderstorm Warning | BOU | 39 min |
| Jun 7, 5:06 PM MDT | Tornado Warning | BOU | 24 min |
| Jun 7, 5:28 PM MDT | Tornado Warning | BOU | 32 min |
| Jun 7, 5:52 PM MDT | Mesoscale Discussion | SPC | 53 min |
| Jun 7, 5:59 PM MDT | Severe Thunderstorm Warning | BOU | 31 min |
| Jun 7, 7:43 PM MDT | Mesoscale Discussion | SPC | 32 min |
| Jun 15, 2:50 AM MDT | Special Weather Statement | BOU | 40 min |
| Jun 15, 12:54 PM MDT | Mesoscale Discussion | SPC | 96 min |
| Jun 15, 1:35 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 15, 2:20 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| Jun 15, 3:27 PM MDT | Special Weather Statement | BOU | 33 min |
| Jun 15, 3:52 PM MDT | Severe Thunderstorm Warning | BOU | 38 min |
| Jun 15, 4:31 PM MDT | Special Weather Statement | BOU | 29 min |
| Jun 21, 3:16 PM MDT | Red Flag Warning | BOU | 54 hr |
| Jun 24, 2:54 PM MDT | Red Flag Warning | BOU | 30 hr |
| Jun 26, 5:43 PM MDT | Severe Thunderstorm Warning | BOU | 47 min |
| Jun 27, 1:25 PM MDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 27, 4:49 PM MDT | Severe Thunderstorm Warning | BOU | 41 min |
| Jul 6, 6:29 PM MDT | Severe Thunderstorm Warning | BOU | 43 min |
| Jul 6, 8:41 PM MDT | Flash Flood Watch | BOU | 32 hr |
| Jul 7, 4:19 PM MDT | Areal Flood Advisory | BOU | 86 min |
| Jul 8, 5:05 AM MDT | Flash Flood Watch | BOU | 18 hr |
| Jul 9, 9:47 AM MDT | Areal Flood Advisory | BOU | 88 min |
| Jul 30, 3:45 PM MDT | Mesoscale Discussion | SPC | 60 min |
| Jul 31, 2:05 PM MDT | Mesoscale Discussion | SPC | 55 min |
| Jul 31, 3:28 PM MDT | Severe Thunderstorm Warning | BOU | 31 min |
| Aug 28, 3:03 PM MDT | Red Flag Warning | BOU | 29 hr |
| Aug 29, 2:40 PM MDT | Red Flag Warning | BOU | 29 hr |
| Aug 31, 9:15 AM MDT | Red Flag Warning | BOU | 11 hr |
| Sep 1, 3:43 AM MDT | Red Flag Warning | BOU | 15 hr |
| Sep 8, 2:44 PM MDT | Fire Weather Watch | BOU | 13 hr |
| Sep 9, 3:43 AM MDT | Red Flag Warning | BOU | 15 hr |
| Sep 27, 2:09 PM MDT | Mesoscale Discussion | SPC | 66 min |
| Oct 3, 11:26 AM MDT | Red Flag Warning | BOU | 7 hr |
| Oct 3, 8:26 PM MDT | Freeze Warning | BOU | 13 hr |
| Oct 4, 4:21 PM MDT | Frost Advisory | BOU | 17 hr |
| Oct 4, 4:21 PM MDT | Freeze Watch | BOU | 13 hr |
| Oct 5, 5:03 AM MDT | Freeze Warning | BOU | 29 hr |
| Oct 5, 2:59 PM MDT | Hard Freeze Warning | BOU | 42 hr |
| Oct 16, 3:52 AM MDT | Fire Weather Watch | BOU | 12 hr |
| Oct 16, 3:49 PM MDT | Red Flag Warning | BOU | 26 hr |
| Oct 17, 2:26 PM MDT | Red Flag Warning | BOU | 28 hr |
| Nov 9, 4:02 AM MST | Winter Weather Advisory | BOU | 49 hr |
| Dec 16, 4:32 AM MST | Dense Fog Advisory | BOU | 4 hr |
| Dec 17, 3:36 PM MST | Winter Storm Watch | BOU | 22 hr |
| Dec 18, 1:56 PM MST | Blizzard Warning | BOU | 28 hr |
| Dec 18, 1:56 PM MST | Winter Weather Advisory | BOU | 25 hr |
| Dec 19, 3:13 AM MST | Winter Weather Advisory | BOU | 12 hr |
| Dec 23, 3:28 PM MST | Winter Weather Advisory | BOU | 38 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20112013
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.