Alert archive / Colorado / Jefferson County
Weather alerts in Jefferson County, Colorado, 2018
129 weather alerts in 2018, 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 2018. Tap one for its archive.
- Alerts
- 129
- Warnings
- 41
- Watches
- 20
- Advisories
- 41
- Busiest month
- July25 alerts
- Busiest day
- July 25, 20186 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Jefferson County, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 13 | 7 | 46% | 19 | 68% | 16 min |
| Flash flood warnings | 1 | 0 | 100% | 0 |
Each office's whole area, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Denver/Boulder, CO: tornado warnings | 52 | 11 | 79% | 36 | 53% | 12 min |
| NWS Denver/Boulder, CO: severe thunderstorm warnings | 322 | 114 | 65% | 369 | 75% | 20 min |
| NWS Denver/Boulder, CO: flash flood warnings | 13 | 3 | 77% | 14 | 79% | 32 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 6, 3:35 AM MST | Winter Weather Advisory | BOU | 25 hr |
| Jan 9, 4:19 AM MST | Winter Weather Advisory | BOU | 44 hr |
| Jan 11, 10:44 AM MST | Winter Weather Advisory | BOU | 28 hr |
| Jan 15, 6:46 AM MST | Winter Weather Advisory | BOU | 6 hr |
| Jan 19, 1:54 PM MST | Winter Storm Watch | BOU | 16 hr |
| Jan 20, 5:24 AM MST | Winter Storm Warning | BOU | 36 hr |
| Jan 30, 7:05 PM MST | High Wind Warning | BOU | 8 hr |
| Feb 2, 4:13 PM MST | Winter Weather Advisory | BOU | 43 hr |
| Feb 4, 2:26 PM MST | Winter Weather Advisory | BOU | 37 hr |
| Feb 5, 4:32 PM MST | Winter Storm Warning | BOU | 11 hr |
| Feb 6, 3:16 AM MST | Winter Weather Advisory | BOU | 7 hr |
| Feb 9, 3:18 PM MST | Winter Weather Advisory | BOU | 26 hr |
| Feb 9, 5:37 PM MST | Dense Fog Advisory | BOU | 3 hr |
| Feb 14, 3:19 AM MST | Winter Storm Warning | BOU | 39 hr |
| Feb 15, 3:52 PM MST | High Wind Watch | BOU | 17 hr |
| Feb 16, 9:13 AM MST | High Wind Warning | BOU | 49 hr |
| Feb 18, 2:01 PM MST | Winter Weather Advisory | BOU | 34 hr |
| Mar 3, 3:03 PM MST | Winter Weather Advisory | BOU | 41 hr |
| Mar 3, 3:17 PM MST | Fire Weather Watch | BOU | 19 hr |
| Mar 3, 3:17 PM MST | Red Flag Warning | BOU | 28 hr |
| Mar 4, 9:49 AM MST | Red Flag Warning | BOU | 32 hr |
| Mar 15, 3:45 AM MDT | Winter Weather Advisory | BOU | 25 hr |
| Mar 15, 3:54 AM MDT | High Wind Watch | BOU | 11 hr |
| Mar 17, 2:40 PM MDT | Winter Weather Advisory | BOU | 37 hr |
| Mar 22, 4:43 AM MDT | Winter Weather Advisory | BOU | 37 hr |
| Mar 26, 4:27 AM MDT | Winter Weather Advisory | BOU | 24 hr |
| Apr 2, 1:46 PM MDT | High Wind Warning | BOU | 21 hr |
| Apr 5, 4:01 AM MDT | Winter Weather Advisory | BOU | 44 hr |
| Apr 7, 4:26 AM MDT | Winter Storm Warning | BOU | 29 hr |
| Apr 10, 3:44 AM MDT | Red Flag Warning | BOU | 39 hr |
| Apr 10, 3:44 AM MDT | Red Flag Warning | BOU | 65 hr |
| Apr 11, 3:08 PM MDT | Winter Weather Advisory | BOU | 54 hr |
| Apr 16, 3:45 AM MDT | Red Flag Warning | BOU | 42 hr |
| Apr 17, 4:58 AM MDT | High Wind Warning | BOU | 16 hr |
| Apr 18, 8:27 PM MDT | Red Flag Warning | BOU | 24 hr |
| Apr 19, 4:41 AM MDT | Winter Storm Watch | BOU | 11 hr |
| Apr 19, 3:14 PM MDT | Winter Storm Warning | BOU | 28 hr |
| Apr 19, 3:14 PM MDT | Winter Weather Advisory | BOU | 44 hr |
| Apr 29, 2:53 PM MDT | Red Flag Warning | BOU | 28 hr |
| May 2, 4:56 AM MDT | Winter Weather Advisory | BOU | 31 hr |
| May 11, 10:58 PM MDT | Dense Fog Advisory | BOU | 10 hr |
| May 13, 12:22 AM MDT | Dense Fog Advisory | BOU | 9 hr |
| May 14, 11:30 AM MDT | Special Weather Statement | BOU | 45 min |
| May 14, 12:09 PM MDT | Special Weather Statement | BOU | 21 min |
| May 14, 12:43 PM MDT | Special Weather Statement | BOU | 47 min |
| May 14, 12:54 PM MDT | Areal Flood Advisory | BOU | 38 min |
| May 18, 3:48 AM MDT | Winter Storm Watch | BOU | 11 hr |
| May 18, 11:02 AM MDT | Flash Flood Watch | BOU | 30 hr |
| May 18, 2:29 PM MDT | Winter Weather Advisory | BOU | 13 hr |
| May 18, 3:06 PM MDT | Mesoscale Discussion | SPC | 114 min |
| May 28, 1:39 PM MDT | Mesoscale Discussion | SPC | 96 min |
| May 28, 2:01 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| May 28, 2:55 PM MDT | Special Weather Statement | BOU | 50 min |
| May 28, 3:25 PM MDT | Severe Thunderstorm Warning | BOU | 50 min |
| May 28, 4:13 PM MDT | Severe Thunderstorm Warning | BOU | 47 min |
| May 31, 6:20 PM MDT | Red Flag Warning | BOU | 27 hr |
| Jun 6, 7:51 PM MDT | Special Weather Statement | BOU | 39 min |
| Jun 6, 7:55 PM MDT | Severe Thunderstorm Warning | BOU | 35 min |
| Jun 8, 3:17 PM MDT | Fire Weather Watch | BOU | 18 hr |
| Jun 9, 9:00 AM MDT | Red Flag Warning | BOU | 37 hr |
| Jun 14, 3:27 AM MDT | Red Flag Warning | BOU | 17 hr |
| Jun 18, 8:16 PM MDT | Severe Thunderstorm Warning | BOU | 29 min |
| Jun 19, 12:25 PM MDT | Tornado Watch | SPC | 7 hr |
| Jun 19, 12:53 PM MDT | Severe Thunderstorm Warning | BOU | 52 min |
| Jun 19, 1:54 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 27, 3:39 AM MDT | Red Flag Warning | BOU | 42 hr |
| Jul 4, 1:51 PM MDT | Mesoscale Discussion | SPC | 54 min |
| Jul 4, 8:14 PM MDT | Special Weather Statement | BOU | 46 min |
| Jul 5, 10:16 AM MDT | Flash Flood Watch | BOU | 9 hr |
| Jul 5, 3:19 PM MDT | Flash Flood Warning | BOU | 115 min |
| Jul 8, 7:11 PM MDT | Special Weather Statement | BOU | 34 min |
| Jul 15, 4:14 AM MDT | Flash Flood Watch | BOU | 16 hr |
| Jul 23, 1:00 PM MDT | Mesoscale Discussion | SPC | 90 min |
| Jul 23, 1:27 PM MDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 23, 1:51 PM MDT | Severe Thunderstorm Warning | BOU | 24 min |
| Jul 23, 2:14 PM MDT | Severe Thunderstorm Warning | BOU | 46 min |
| Jul 23, 4:07 PM MDT | Areal Flood Advisory | BOU | 83 min |
| Jul 23, 7:42 PM MDT | Areal Flood Advisory | BOU | 80 min |
| Jul 24, 4:05 PM MDT | Special Weather Statement | BOU | 40 min |
| Jul 24, 5:15 PM MDT | Special Weather Statement | BOU | 45 min |
| Jul 24, 5:56 PM MDT | Severe Thunderstorm Warning | BOU | 49 min |
| Jul 24, 6:13 PM MDT | Areal Flood Advisory | BOU | 32 min |
| Jul 25, 10:41 AM MDT | Flash Flood Watch | BOU | 11 hr |
| Jul 25, 12:48 PM MDT | Mesoscale Discussion | SPC | 57 min |
| Jul 25, 1:22 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 25, 3:43 PM MDT | Special Weather Statement | BOU | 47 min |
| Jul 25, 5:08 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 26, 12:49 PM MDT | Mesoscale Discussion | SPC | 56 min |
| Jul 26, 1:49 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 26, 6:07 PM MDT | Mesoscale Discussion | SPC | 113 min |
| Jul 27, 4:57 PM MDT | Severe Thunderstorm Warning | BOU | 33 min |
| Aug 3, 8:16 PM MDT | Special Weather Statement | BOU | 44 min |
| Aug 3, 8:39 PM MDT | Severe Thunderstorm Warning | BOU | 51 min |
| Aug 6, 2:37 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 6, 5:24 PM MDT | Mesoscale Discussion | SPC | 66 min |
| Aug 6, 8:06 PM MDT | Mesoscale Discussion | SPC | 54 min |
| Aug 7, 12:59 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 7, 7:57 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 14, 4:56 PM MDT | Severe Thunderstorm Warning | BOU | 49 min |
| Aug 14, 5:31 PM MDT | Mesoscale Discussion | SPC | 119 min |
| Aug 14, 5:39 PM MDT | Severe Thunderstorm Warning | BOU | 51 min |
| Aug 17, 2:56 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 18, 11:33 AM MDT | Special Weather Statement | BOU | 42 min |
| Aug 26, 3:58 AM MDT | Fire Weather Watch | BOU | 12 hr |
| Aug 26, 3:35 PM MDT | Red Flag Warning | BOU | 26 hr |
| Sep 4, 11:34 PM MDT | Areal Flood Advisory | BOU | 86 min |
| Sep 5, 2:08 AM MDT | Areal Flood Advisory | BOU | 97 min |
| Sep 5, 2:31 AM MDT | Areal Flood Advisory | BOU | 89 min |
| Sep 5, 3:14 PM MDT | Areal Flood Advisory | BOU | 61 min |
| Sep 28, 10:32 AM MDT | Red Flag Warning | BOU | 32 hr |
| Oct 7, 2:30 PM MDT | Freeze Watch | BOU | 25 hr |
| Oct 8, 3:01 PM MDT | Freeze Warning | BOU | 13 hr |
| Oct 9, 4:25 AM MDT | Freeze Warning | BOU | 30 hr |
| Oct 9, 3:24 PM MDT | Winter Weather Advisory | BOU | 30 hr |
| Oct 10, 2:24 PM MDT | Winter Weather Advisory | BOU | 34 hr |
| Oct 10, 2:27 PM MDT | Freeze Warning | BOU | 19 hr |
| Oct 12, 2:20 PM MDT | Winter Weather Advisory | BOU | 49 hr |
| Oct 29, 3:56 AM MDT | Winter Weather Advisory | BOU | 50 hr |
| Nov 1, 3:02 PM MDT | Winter Weather Advisory | BOU | 49 hr |
| Nov 2, 10:35 PM MDT | Severe Thunderstorm Warning | BOU | 33 min |
| Nov 3, 3:32 PM MDT | Winter Weather Advisory | BOU | 44 hr |
| Nov 10, 4:18 AM MST | Winter Weather Advisory | BOU | 44 hr |
| Nov 16, 10:36 AM MST | Winter Weather Advisory | BOU | 34 hr |
| Nov 21, 2:50 PM MST | Winter Storm Watch | BOU | 25 hr |
| Nov 22, 3:49 PM MST | Winter Storm Warning | BOU | 58 hr |
| Nov 24, 5:39 AM MST | High Wind Warning | BOU | 19 hr |
| Dec 1, 2:47 AM MST | Dense Fog Advisory | BOU | 4 hr |
| Dec 18, 10:08 AM MST | Winter Weather Advisory | BOU | 31 hr |
| Dec 30, 1:56 PM MST | Winter Weather Advisory | BOU | 27 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 |
| Severe Thunderstorm Watch | 5 |
| Tornado Watch | 1 |
| Mesoscale Discussion | 15 |
| Special Weather Statement | 12 |
| Flooding | |
| Flash Flood Warning | 1 |
| Flash Flood Watch | 4 |
| Areal Flood Advisory | 8 |
| Winter | |
| Winter Storm Warning | 6 |
| Winter Storm Watch | 4 |
| Winter Weather Advisory | 29 |
| Cold | |
| Freeze Warning | 3 |
| Freeze Watch | 1 |
| Wind and dust | |
| High Wind Warning | 5 |
| High Wind Watch | 2 |
| Fire | |
| Red Flag Warning | 13 |
| 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 archive20172019
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.