Alert archive / Colorado / Arapahoe County
Weather alerts in Arapahoe County, Colorado, 2019
200 weather alerts in 2019, 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 2019. Tap one for its archive.
- Alerts
- 200
- Warnings
- 54
- Watches
- 36
- Advisories
- 38
- Busiest month
- June37 alerts
- Busiest day
- July 6, 20197 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 Arapahoe County in 2019 had a tornado report inside them.
Arapahoe County, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 2 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 29 | 14 | 52% | 23 | 74% | 24 min |
| Flash flood warnings | 3 | 1 | 67% | 0 |
Each office's whole area, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Denver/Boulder, CO: tornado warnings | 32 | 11 | 66% | 33 | 48% | 11 min |
| NWS Denver/Boulder, CO: severe thunderstorm warnings | 281 | 117 | 58% | 382 | 77% | 18 min |
| NWS Denver/Boulder, CO: flash flood warnings | 15 | 2 | 87% | 3 | 67% | 58 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, 8:09 PM MST | High Wind Watch | BOU | 7 hr |
| Jan 10, 2:42 PM MST | Winter Weather Advisory | BOU | 33 hr |
| Jan 11, 3:24 AM MST | Winter Storm Warning | BOU | 25 hr |
| Jan 20, 3:01 PM MST | Winter Storm Watch | BOU | 20 hr |
| Jan 20, 3:01 PM MST | Winter Weather Advisory | BOU | 42 hr |
| Jan 21, 11:18 AM MST | Blizzard Warning | BOU | 24 hr |
| Jan 22, 10:55 AM MST | Blizzard Warning | BOU | 4 hr |
| Jan 27, 9:05 PM MST | Special Weather Statement | BOU | 40 min |
| Feb 5, 4:11 AM MST | Winter Weather Advisory | BOU | 48 hr |
| Feb 20, 3:59 PM MST | Winter Weather Advisory | BOU | 66 hr |
| Feb 25, 11:00 PM MST | Dense Fog Advisory | BOU | 9 hr |
| Feb 27, 3:10 AM MST | Dense Fog Advisory | BOU | 6 hr |
| Feb 28, 5:33 PM MST | Winter Storm Watch | BOU | 17 hr |
| Feb 28, 5:33 PM MST | Winter Weather Advisory | BOU | 58 hr |
| Mar 2, 6:44 PM MST | Mesoscale Discussion | SPC | 4 hr |
| Mar 3, 3:36 AM MST | Wind Chill Advisory | BOU | 5 hr |
| Mar 3, 3:36 AM MST | Wind Chill Advisory | BOU | 29 hr |
| Mar 11, 6:48 AM MDT | Winter Storm Watch | BOU | 28 hr |
| Mar 11, 3:24 PM MDT | Blizzard Warning | BOU | 68 hr |
| Mar 13, 10:27 AM MDT | Mesoscale Discussion | SPC | 3 hr |
| Mar 13, 1:37 PM MDT | Mesoscale Discussion | SPC | 4 hr |
| Mar 13, 5:26 PM MDT | Mesoscale Discussion | SPC | 6 hr |
| Mar 14, 11:52 AM MDT | Winter Weather Advisory | BOU | 6 hr |
| Apr 7, 3:05 PM MDT | Fire Weather Watch | BOU | 21 hr |
| Apr 8, 12:03 PM MDT | Red Flag Warning | BOU | 31 hr |
| Apr 8, 3:10 PM MDT | Winter Storm Watch | BOU | 21 hr |
| Apr 9, 11:47 AM MDT | Blizzard Warning | BOU | 47 hr |
| Apr 10, 8:31 PM MDT | Winter Weather Advisory | BOU | 22 hr |
| Apr 21, 2:00 PM MDT | Special Weather Statement | BOU | 30 min |
| May 6, 12:50 PM MDT | Mesoscale Discussion | SPC | 115 min |
| May 7, 1:01 AM MDT | Dense Fog Advisory | BOU | 7 hr |
| May 7, 12:29 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| May 7, 8:53 PM MDT | Dense Fog Advisory | BOU | 12 hr |
| May 8, 3:50 PM MDT | Freeze Watch | BOU | 24 hr |
| May 9, 4:03 PM MDT | Frost Advisory | BOU | 16 hr |
| May 10, 2:51 PM MDT | Frost Advisory | BOU | 18 hr |
| May 11, 5:45 PM MDT | Frost Advisory | BOU | 14 hr |
| May 16, 4:36 PM MDT | Special Weather Statement | BOU | 39 min |
| May 18, 12:20 PM MDT | Special Weather Statement | BOU | 40 min |
| May 18, 2:49 PM MDT | Frost Advisory | BOU | 17 hr |
| May 19, 2:56 PM MDT | Winter Storm Warning | BOU | 47 hr |
| May 20, 4:50 AM MDT | Winter Weather Advisory | BOU | 31 hr |
| May 21, 12:01 PM MDT | Freeze Warning | BOU | 19 hr |
| May 26, 2:07 PM MDT | Mesoscale Discussion | SPC | 113 min |
| May 26, 3:46 PM MDT | Tornado Watch | SPC | 4 hr |
| May 26, 4:34 PM MDT | Tornado Warning | BOU | 26 min |
| May 26, 5:23 PM MDT | Severe Thunderstorm Warning | BOU | 32 min |
| May 27, 12:36 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| May 27, 12:50 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| May 27, 12:56 PM MDT | Tornado Watch | SPC | 8 hr |
| May 27, 2:43 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 1, 2:12 PM MDT | Severe Thunderstorm Warning | BOU | 48 min |
| Jun 1, 2:42 PM MDT | Severe Thunderstorm Warning | BOU | 37 min |
| Jun 2, 10:57 AM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 2, 12:11 PM MDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 2, 2:26 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 3, 1:31 PM MDT | Mesoscale Discussion | SPC | 119 min |
| Jun 3, 1:32 PM MDT | Special Weather Statement | BOU | 28 min |
| Jun 3, 1:53 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 3, 2:00 PM MDT | Special Weather Statement | BOU | 30 min |
| Jun 3, 2:22 PM MDT | Special Weather Statement | BOU | 23 min |
| Jun 4, 12:59 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 7, 12:37 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 7, 6:41 PM MDT | Severe Thunderstorm Warning | BOU | 34 min |
| Jun 8, 3:44 PM MDT | Mesoscale Discussion | SPC | 61 min |
| Jun 8, 3:44 PM MDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 8, 5:45 PM MDT | Severe Thunderstorm Warning | BOU | 45 min |
| Jun 8, 5:48 PM MDT | Severe Thunderstorm Warning | BOU | 27 min |
| Jun 8, 5:58 PM MDT | Severe Thunderstorm Warning | BOU | 32 min |
| Jun 8, 6:19 PM MDT | Mesoscale Discussion | SPC | 86 min |
| Jun 8, 6:28 PM MDT | Severe Thunderstorm Warning | BOU | 32 min |
| Jun 8, 8:09 PM MDT | Mesoscale Discussion | SPC | 96 min |
| Jun 13, 5:58 PM MDT | Mesoscale Discussion | SPC | 92 min |
| Jun 14, 12:44 PM MDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 17, 12:04 PM MDT | Mesoscale Discussion | SPC | 86 min |
| Jun 17, 4:30 PM MDT | Mesoscale Discussion | SPC | 90 min |
| Jun 17, 4:31 PM MDT | Flash Flood Warning | BOU | 43 min |
| Jun 20, 2:47 PM MDT | Severe Thunderstorm Warning | BOU | 43 min |
| Jun 20, 2:51 PM MDT | Mesoscale Discussion | SPC | 114 min |
| Jun 20, 3:16 PM MDT | Special Weather Statement | BOU | 29 min |
| Jun 20, 5:13 PM MDT | Severe Thunderstorm Warning | BOU | 32 min |
| Jun 21, 11:56 AM MDT | Mesoscale Discussion | SPC | 94 min |
| Jun 21, 12:42 PM MDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 22, 2:11 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 22, 4:08 PM MDT | Mesoscale Discussion | SPC | 67 min |
| Jun 25, 2:13 PM MDT | Special Weather Statement | BOU | 47 min |
| Jun 28, 9:17 PM MDT | Special Weather Statement | BOU | 43 min |
| Jun 28, 9:55 PM MDT | Special Weather Statement | BOU | 50 min |
| Jul 1, 4:00 PM MDT | Areal Flood Advisory | BOU | 90 min |
| Jul 1, 11:02 PM MDT | Areal Flood Advisory | BOU | 118 min |
| Jul 4, 2:10 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 4, 3:01 PM MDT | Tornado Watch | SPC | 7 hr |
| Jul 4, 5:26 PM MDT | Severe Thunderstorm Warning | BOU | 15 min |
| Jul 4, 5:39 PM MDT | Severe Thunderstorm Warning | BOU | 23 min |
| Jul 4, 5:40 PM MDT | Mesoscale Discussion | SPC | 95 min |
| Jul 4, 6:33 PM MDT | Severe Thunderstorm Warning | BOU | 18 min |
| Jul 4, 6:48 PM MDT | Severe Thunderstorm Warning | BOU | 27 min |
| Jul 5, 1:18 PM MDT | Mesoscale Discussion | SPC | 117 min |
| Jul 5, 3:36 PM MDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 5, 6:01 PM MDT | Mesoscale Discussion | SPC | 89 min |
| Jul 5, 6:10 PM MDT | Severe Thunderstorm Warning | BOU | 50 min |
| Jul 5, 6:27 PM MDT | Areal Flood Advisory | BOU | 112 min |
| Jul 5, 9:18 PM MDT | Mesoscale Discussion | SPC | 57 min |
| Jul 6, 12:25 PM MDT | Mesoscale Discussion | SPC | 95 min |
| Jul 6, 12:42 PM MDT | Severe Thunderstorm Watch | SPC | 10 hr |
| Jul 6, 4:55 PM MDT | Mesoscale Discussion | SPC | 95 min |
| Jul 7, 2:14 PM MDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 13, 5:51 PM MDT | Areal Flood Advisory | BOU | 65 min |
| Jul 20, 12:53 PM MDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 20, 2:29 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 20, 3:05 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| Jul 20, 3:22 PM MDT | Areal Flood Advisory | BOU | 83 min |
| Jul 20, 5:43 PM MDT | Mesoscale Discussion | SPC | 92 min |
| Jul 21, 4:37 PM MDT | Mesoscale Discussion | SPC | 83 min |
| Jul 21, 6:53 PM MDT | Severe Thunderstorm Warning | BOU | 52 min |
| Jul 22, 5:07 PM MDT | Severe Thunderstorm Warning | BOU | 23 min |
| Jul 22, 5:38 PM MDT | Mesoscale Discussion | SPC | 67 min |
| Jul 24, 6:29 PM MDT | Special Weather Statement | BOU | 31 min |
| Jul 24, 6:58 PM MDT | Special Weather Statement | BOU | 32 min |
| Jul 29, 1:52 PM MDT | Mesoscale Discussion | SPC | 113 min |
| Jul 30, 5:31 PM MDT | Severe Thunderstorm Warning | BOU | 29 min |
| Aug 1, 3:14 AM MDT | Flash Flood Watch | BOU | 20 hr |
| Aug 1, 1:25 PM MDT | Mesoscale Discussion | SPC | 95 min |
| Aug 1, 1:46 PM MDT | Special Weather Statement | BOU | 29 min |
| Aug 1, 1:55 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 5, 5:15 PM MDT | Special Weather Statement | BOU | 45 min |
| Aug 8, 2:36 PM MDT | Special Weather Statement | BOU | 39 min |
| Aug 11, 12:54 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 11, 1:24 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 11, 2:27 PM MDT | Severe Thunderstorm Warning | BOU | 25 min |
| Aug 11, 3:24 PM MDT | Severe Thunderstorm Warning | BOU | 36 min |
| Aug 11, 3:28 PM MDT | Severe Thunderstorm Warning | BOU | 32 min |
| Aug 11, 4:51 PM MDT | Mesoscale Discussion | SPC | 114 min |
| Aug 14, 1:54 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 14, 3:00 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 14, 5:58 PM MDT | Mesoscale Discussion | SPC | 92 min |
| Aug 16, 1:40 PM MDT | Mesoscale Discussion | SPC | 65 min |
| Aug 16, 2:54 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 16, 5:27 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 16, 7:43 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 17, 12:43 PM MDT | Special Weather Statement | BOU | 32 min |
| Aug 17, 1:34 PM MDT | Mesoscale Discussion | SPC | 116 min |
| Aug 21, 12:51 PM MDT | Mesoscale Discussion | SPC | 114 min |
| Aug 21, 2:47 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 21, 6:22 PM MDT | Areal Flood Advisory | BOU | 113 min |
| Aug 21, 6:34 PM MDT | Severe Thunderstorm Warning | BOU | 41 min |
| Aug 21, 6:40 PM MDT | Flash Flood Warning | BOU | 2 hr |
| Aug 22, 2:11 PM MDT | Mesoscale Discussion | SPC | 94 min |
| Aug 23, 1:55 PM MDT | Mesoscale Discussion | SPC | 110 min |
| Aug 23, 2:34 PM MDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 23, 4:28 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 30, 2:13 PM MDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 6, 2:44 PM MDT | Severe Thunderstorm Warning | BOU | 46 min |
| Sep 6, 3:26 PM MDT | Severe Thunderstorm Warning | BOU | 34 min |
| Sep 6, 3:59 PM MDT | Severe Thunderstorm Warning | BOU | 46 min |
| Sep 6, 4:01 PM MDT | Flash Flood Warning | BOU | 89 min |
| Sep 6, 4:10 PM MDT | Tornado Warning | BOU | 21 min |
| Sep 6, 4:43 PM MDT | Areal Flood Advisory | BOU | 68 min |
| Sep 8, 2:40 PM MDT | Mesoscale Discussion | SPC | 95 min |
| Sep 8, 2:56 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Sep 8, 6:05 PM MDT | Severe Thunderstorm Warning | BOU | 40 min |
| Sep 8, 6:34 PM MDT | Severe Thunderstorm Warning | BOU | 41 min |
| Sep 20, 10:02 AM MDT | Red Flag Warning | BOU | 10 hr |
| Sep 27, 3:02 PM MDT | Fire Weather Watch | BOU | 13 hr |
| Sep 27, 3:02 PM MDT | Fire Weather Watch | BOU | 37 hr |
| Sep 28, 4:15 AM MDT | Red Flag Warning | BOU | 39 hr |
| Sep 29, 3:56 AM MDT | Red Flag Warning | BOU | 39 hr |
| Oct 2, 2:26 AM MDT | Frost Advisory | BOU | 30 hr |
| Oct 6, 3:37 AM MDT | Frost Advisory | BOU | 28 hr |
| Oct 6, 3:37 AM MDT | Freeze Watch | BOU | 10 hr |
| Oct 7, 2:24 PM MDT | Fire Weather Watch | BOU | 14 hr |
| Oct 8, 4:51 AM MDT | Red Flag Warning | BOU | 37 hr |
| Oct 8, 3:06 PM MDT | Freeze Watch | BOU | 13 hr |
| Oct 9, 4:18 AM MDT | Freeze Warning | BOU | 29 hr |
| Oct 9, 3:17 PM MDT | Winter Weather Advisory | BOU | 23 hr |
| Oct 15, 2:07 PM MDT | Fire Weather Watch | BOU | 24 hr |
| Oct 18, 2:31 PM MDT | Fire Weather Watch | BOU | 23 hr |
| Oct 19, 1:34 PM MDT | Red Flag Warning | BOU | 29 hr |
| Oct 22, 3:26 AM MDT | Winter Storm Watch | BOU | 24 hr |
| Oct 23, 3:54 AM MDT | Winter Storm Warning | BOU | 27 hr |
| Oct 23, 3:54 AM MDT | Winter Weather Advisory | BOU | 27 hr |
| Oct 25, 1:52 PM MDT | Winter Storm Watch | BOU | 24 hr |
| Oct 26, 1:54 PM MDT | Winter Weather Advisory | BOU | 46 hr |
| Oct 28, 5:17 AM MDT | Mesoscale Discussion | SPC | 3 hr |
| Oct 28, 2:26 PM MDT | Winter Storm Warning | BOU | 37 hr |
| Nov 6, 2:54 PM MST | Winter Weather Advisory | BOU | 12 hr |
| Nov 10, 2:55 PM MST | Winter Weather Advisory | BOU | 18 hr |
| Nov 21, 4:11 AM MST | Winter Weather Advisory | BOU | 5 hr |
| Nov 24, 4:38 AM MST | Winter Storm Watch | BOU | 9 hr |
| Nov 24, 1:40 PM MST | Winter Storm Warning | BOU | 51 hr |
| Nov 24, 1:40 PM MST | Winter Weather Advisory | BOU | 51 hr |
| Nov 25, 7:42 PM MST | Mesoscale Discussion | SPC | 6 hr |
| Nov 26, 4:16 AM MST | Blizzard Warning | BOU | 8 hr |
| Nov 29, 1:44 AM MST | Dense Fog Advisory | BOU | 9 hr |
| Nov 29, 3:02 AM MST | High Wind Warning | BOU | 39 hr |
| Nov 29, 5:39 PM MST | Dense Fog Advisory | BOU | 6 hr |
| Dec 26, 3:36 AM MST | Winter Storm Watch | BOU | 34 hr |
| Dec 26, 7:16 AM MST | Dense Fog Advisory | BOU | 3 hr |
| Dec 27, 1:57 PM MST | Winter Storm Warning | BOU | 34 hr |
| Dec 27, 1:57 PM MST | Winter Weather Advisory | BOU | 34 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 | 29 |
| Tornado Warning | 2 |
| Severe Thunderstorm Watch | 14 |
| Tornado Watch | 3 |
| Mesoscale Discussion | 55 |
| Special Weather Statement | 17 |
| Flooding | |
| Flash Flood Warning | 3 |
| Flash Flood Watch | 1 |
| Areal Flood Advisory | 7 |
| Winter | |
| Blizzard Warning | 5 |
| Winter Storm Warning | 6 |
| Winter Storm Watch | 8 |
| Winter Weather Advisory | 16 |
| Cold | |
| Freeze Warning | 2 |
| Freeze Watch | 3 |
| Frost Advisory | 6 |
| Wind Chill Advisory | 2 |
| Wind and dust | |
| High Wind Warning | 1 |
| High Wind Watch | 1 |
| Fire | |
| Red Flag Warning | 6 |
| Fire Weather Watch | 6 |
| Fog and smoke | |
| Dense Fog Advisory | 7 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20182020
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.