Alert archive / Colorado / Jefferson County
Weather alerts in Jefferson County, Colorado, 2009
131 weather alerts in 2009, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Jefferson County and its neighbors
Each county as a circle sized by its count in 2009. Tap one for its archive.
- Alerts
- 131
- Warnings
- 48
- Watches
- 19
- Advisories
- 38
- Busiest month
- June26 alerts
- Busiest day
- June 14, 20095 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
0 of 2 tornado warnings covering Jefferson County in 2009 had a tornado report inside them; 0 of 1 tornado reports fell inside a warning.
Jefferson County, 2009
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 2 | 0 | 100% | 1 | 0% | |
| Severe thunderstorm warnings | 13 | 8 | 38% | 23 | 70% | 12 min |
| Flash flood warnings | 2 | 0 | 100% | 0 |
Each office's whole area, 2009
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Denver/Boulder, CO: tornado warnings | 81 | 16 | 80% | 45 | 44% | 12 min |
| NWS Denver/Boulder, CO: severe thunderstorm warnings | 279 | 128 | 54% | 321 | 70% | 17 min |
| NWS Denver/Boulder, CO: flash flood warnings | 19 | 6 | 68% | 13 | 62% | 43 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 |
|---|---|---|---|
| Jan 5, 3:55 PM MST | High Wind Watch | BOU | 24 hr |
| Jan 6, 4:48 AM MST | Winter Weather Advisory | BOU | 26 hr |
| Jan 6, 3:49 PM MST | High Wind Warning | BOU | 32 hr |
| Jan 7, 6:43 AM MST | Winter Storm Warning | BOU | 10 hr |
| Jan 12, 12:58 AM MST | Winter Weather Advisory | BOU | 15 hr |
| Jan 12, 8:49 AM MST | Winter Weather Advisory | BOU | 2 hr |
| Jan 13, 4:58 AM MST | Winter Weather Advisory | BOU | 11 hr |
| Jan 22, 5:44 AM MST | Red Flag Warning | BOU | 12 hr |
| Jan 24, 3:39 AM MST | Winter Storm Warning | BOU | 68 hr |
| Jan 24, 3:39 AM MST | Winter Weather Advisory | BOU | 68 hr |
| Jan 27, 3:14 PM MST | Winter Weather Advisory | BOU | 12 hr |
| Jan 27, 9:53 PM MST | High Wind Warning | BOU | 13 hr |
| Jan 28, 3:30 AM MST | Winter Weather Advisory | BOU | 30 hr |
| Feb 5, 2:08 PM MST | Red Flag Warning | BOU | 29 hr |
| Feb 9, 9:02 AM MST | High Wind Warning | BOU | 9 hr |
| Feb 17, 12:16 PM MST | Red Flag Warning | BOU | 6 hr |
| Feb 20, 4:35 AM MST | Red Flag Warning | BOU | 12 hr |
| Feb 26, 3:11 PM MST | Winter Weather Advisory | BOU | 24 hr |
| Mar 2, 3:57 AM MST | Red Flag Warning | BOU | 16 hr |
| Mar 2, 3:05 PM MST | Red Flag Warning | BOU | 26 hr |
| Mar 3, 3:01 PM MST | Fire Weather Watch | BOU | 24 hr |
| Mar 4, 3:34 AM MST | Red Flag Warning | BOU | 17 hr |
| Mar 4, 2:42 PM MST | Red Flag Warning | BOU | 27 hr |
| Mar 6, 3:50 AM MST | Red Flag Warning | BOU | 14 hr |
| Mar 8, 1:25 PM MDT | Red Flag Warning | BOU | 5 hr |
| Mar 9, 4:11 AM MDT | Winter Weather Advisory | BOU | 32 hr |
| Mar 14, 3:13 AM MDT | Fire Weather Watch | BOU | 25 hr |
| Mar 15, 4:01 AM MDT | Red Flag Warning | BOU | 16 hr |
| Mar 21, 2:39 PM MDT | Winter Storm Watch | BOU | 14 hr |
| Mar 21, 2:47 PM MDT | Red Flag Warning | BOU | 30 hr |
| Mar 22, 4:38 AM MDT | Winter Storm Warning | BOU | 49 hr |
| Mar 24, 3:59 PM MDT | Winter Storm Watch | BOU | 20 hr |
| Mar 25, 11:47 AM MDT | Winter Storm Warning | BOU | 29 hr |
| Mar 26, 2:57 AM MDT | Blizzard Warning | BOU | 33 hr |
| Mar 26, 6:55 AM MDT | Mesoscale Discussion | SPC | 3 hr |
| Mar 26, 10:35 AM MDT | Mesoscale Discussion | SPC | 5 hr |
| Mar 26, 4:46 PM MDT | Winter Weather Advisory | BOU | 13 hr |
| Mar 29, 4:09 AM MDT | Winter Weather Advisory | BOU | 44 hr |
| Mar 31, 4:27 AM MDT | Winter Weather Advisory | BOU | 44 hr |
| Apr 2, 4:20 AM MDT | Winter Storm Watch | BOU | 32 hr |
| Apr 3, 4:22 AM MDT | Winter Storm Warning | BOU | 32 hr |
| Apr 4, 12:13 PM MDT | Winter Weather Advisory | BOU | 6 hr |
| Apr 15, 4:18 AM MDT | Winter Storm Watch | BOU | 31 hr |
| Apr 16, 4:41 AM MDT | Winter Storm Warning | BOU | 61 hr |
| Apr 17, 1:17 AM MDT | Mesoscale Discussion | SPC | 4 hr |
| May 1, 10:58 AM MDT | Dense Fog Advisory | BOU | 5 hr |
| May 1, 4:05 PM MDT | Dense Fog Advisory | BOU | 8 hr |
| May 24, 3:31 PM MDT | Areal Flood Advisory | BOU | 119 min |
| May 31, 7:20 PM MDT | Areal Flood Advisory | BOU | 85 min |
| Jun 1, 8:07 PM MDT | Areal Flood Advisory | BOU | 53 min |
| Jun 4, 1:27 PM MDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 4, 5:16 PM MDT | Mesoscale Discussion | SPC | 89 min |
| Jun 7, 11:02 AM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 7, 2:30 PM MDT | Mesoscale Discussion | SPC | 60 min |
| Jun 8, 2:03 PM MDT | Mesoscale Discussion | SPC | 87 min |
| Jun 10, 2:33 PM MDT | Special Weather Statement | BOU | 42 min |
| Jun 10, 3:02 PM MDT | Areal Flood Advisory | BOU | 88 min |
| Jun 11, 11:34 AM MDT | Mesoscale Discussion | SPC | 86 min |
| Jun 13, 1:56 PM MDT | Tornado Watch | SPC | 9 hr |
| Jun 13, 3:06 PM MDT | Severe Thunderstorm Warning | BOU | 29 min |
| Jun 13, 5:42 PM MDT | Severe Thunderstorm Warning | BOU | 25 min |
| Jun 13, 6:42 PM MDT | Mesoscale Discussion | SPC | 63 min |
| Jun 14, 1:50 PM MDT | Tornado Watch | SPC | 7 hr |
| Jun 14, 2:35 PM MDT | Severe Thunderstorm Warning | BOU | 10 min |
| Jun 14, 2:42 PM MDT | Tornado Warning | BOU | 48 min |
| Jun 14, 2:44 PM MDT | Areal Flood Advisory | BOU | 91 min |
| Jun 17, 2:30 PM MDT | Tornado Watch | SPC | 8 hr |
| Jun 17, 4:43 PM MDT | Mesoscale Discussion | SPC | 92 min |
| Jun 23, 2:51 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 24, 5:15 PM MDT | Severe Thunderstorm Warning | BOU | 48 min |
| Jun 25, 1:06 PM MDT | Mesoscale Discussion | SPC | 54 min |
| Jun 26, 2:46 PM MDT | Severe Thunderstorm Warning | BOU | 28 min |
| Jun 26, 2:58 PM MDT | Severe Thunderstorm Warning | BOU | 47 min |
| Jun 28, 2:27 PM MDT | Mesoscale Discussion | SPC | 63 min |
| Jul 2, 2:48 PM MDT | Flash Flood Warning | BOU | 2 hr |
| Jul 3, 4:27 PM MDT | Special Weather Statement | BOU | 63 min |
| Jul 4, 1:52 PM MDT | Mesoscale Discussion | SPC | 113 min |
| Jul 6, 1:40 PM MDT | Mesoscale Discussion | SPC | 95 min |
| Jul 6, 2:07 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 6, 5:35 PM MDT | Mesoscale Discussion | SPC | 55 min |
| Jul 10, 9:00 PM MDT | Areal Flood Advisory | BOU | 90 min |
| Jul 12, 2:05 PM MDT | Mesoscale Discussion | SPC | 85 min |
| Jul 13, 12:07 PM MDT | Mesoscale Discussion | SPC | 83 min |
| Jul 13, 1:45 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 20, 10:06 PM MDT | Severe Thunderstorm Warning | BOU | 39 min |
| Jul 20, 10:22 PM MDT | Tornado Warning | BOU | 25 min |
| Jul 20, 10:39 PM MDT | Areal Flood Advisory | BOU | 81 min |
| Jul 20, 10:43 PM MDT | Severe Thunderstorm Warning | BOU | 47 min |
| Jul 21, 2:44 PM MDT | Mesoscale Discussion | SPC | 61 min |
| Jul 21, 9:54 PM MDT | Areal Flood Advisory | BOU | 81 min |
| Jul 22, 1:16 PM MDT | Mesoscale Discussion | SPC | 89 min |
| Jul 25, 9:15 PM MDT | Areal Flood Advisory | BOU | 58 min |
| Aug 3, 3:20 PM MDT | Severe Thunderstorm Warning | BOU | 31 min |
| Aug 5, 7:08 PM MDT | Flash Flood Warning | BOU | 3 hr |
| Aug 5, 9:19 PM MDT | Severe Thunderstorm Warning | BOU | 26 min |
| Aug 6, 3:03 PM MDT | Areal Flood Advisory | BOU | 48 min |
| Aug 6, 4:45 PM MDT | Areal Flood Advisory | BOU | 90 min |
| Aug 9, 7:58 PM MDT | Special Weather Statement | BOU | 32 min |
| Aug 15, 1:07 PM MDT | Mesoscale Discussion | SPC | 53 min |
| Aug 17, 3:51 PM MDT | Mesoscale Discussion | SPC | 84 min |
| Aug 18, 11:41 AM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 18, 12:39 PM MDT | Severe Thunderstorm Warning | BOU | 36 min |
| Aug 18, 1:10 PM MDT | Severe Thunderstorm Warning | BOU | 22 min |
| Aug 25, 1:57 PM MDT | Areal Flood Advisory | BOU | 93 min |
| Aug 25, 2:31 PM MDT | Mesoscale Discussion | SPC | 89 min |
| Aug 29, 2:55 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 13, 4:40 PM MDT | Severe Thunderstorm Warning | BOU | 50 min |
| Sep 22, 4:31 AM MDT | Winter Storm Watch | BOU | 9 hr |
| Sep 22, 1:06 PM MDT | Winter Storm Warning | BOU | 16 hr |
| Sep 29, 3:27 PM MDT | Fire Weather Watch | BOU | 14 hr |
| Sep 30, 4:45 AM MDT | Winter Weather Advisory | BOU | 22 hr |
| Sep 30, 5:00 AM MDT | Red Flag Warning | BOU | 15 hr |
| Sep 30, 2:21 PM MDT | High Wind Warning | BOU | 13 hr |
| Oct 1, 3:05 AM MDT | Freeze Warning | BOU | 29 hr |
| Oct 2, 3:38 PM MDT | Freeze Warning | BOU | 16 hr |
| Oct 14, 4:12 AM MDT | Dense Fog Advisory | BOU | 5 hr |
| Oct 14, 9:07 AM MDT | Dense Fog Advisory | BOU | 113 min |
| Oct 18, 4:35 AM MDT | Red Flag Warning | BOU | 13 hr |
| Oct 20, 3:11 PM MDT | Winter Weather Advisory | BOU | 36 hr |
| Oct 26, 3:15 PM MDT | Winter Storm Watch | BOU | 12 hr |
| Oct 27, 3:26 AM MDT | Winter Storm Warning | BOU | 69 hr |
| Nov 12, 4:48 AM MST | Winter Weather Advisory | BOU | 39 hr |
| Nov 13, 5:06 AM MST | Winter Storm Watch | BOU | 34 hr |
| Nov 14, 10:57 AM MST | Winter Storm Warning | BOU | 26 hr |
| Dec 5, 10:22 AM MST | Winter Weather Advisory | BOU | 24 hr |
| Dec 7, 5:21 AM MST | Winter Weather Advisory | BOU | 47 hr |
| Dec 9, 4:31 AM MST | Wind Chill Warning | BOU | 28 hr |
| Dec 9, 4:31 AM MST | Wind Chill Advisory | BOU | 4 hr |
| Dec 10, 2:41 AM MST | Winter Weather Advisory | BOU | 8 hr |
| Dec 12, 2:41 PM MST | Winter Weather Advisory | BOU | 42 hr |
| Dec 21, 7:53 PM MST | Winter Weather Advisory | BOU | 61 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
| Product | Alerts |
|---|---|
| Severe storms | |
| Severe Thunderstorm Warning | 13 |
| Tornado Warning | 2 |
| Severe Thunderstorm Watch | 5 |
| Tornado Watch | 3 |
| Mesoscale Discussion | 23 |
| Special Weather Statement | 3 |
| Flooding | |
| Flash Flood Warning | 2 |
| Areal Flood Advisory | 12 |
| Winter | |
| Blizzard Warning | 1 |
| Winter Storm Warning | 9 |
| Winter Storm Watch | 7 |
| Winter Weather Advisory | 21 |
| Cold | |
| Freeze Warning | 2 |
| Wind Chill Warning | 1 |
| Wind Chill Advisory | 1 |
| Wind and dust | |
| High Wind Warning | 4 |
| High Wind Watch | 1 |
| Fire | |
| Red Flag Warning | 14 |
| Fire Weather Watch | 3 |
| Fog and smoke | |
| Dense Fog Advisory | 4 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20082010
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.