Alert archive / Colorado / Grand County
Weather alerts in Grand County, Colorado, 2023
91 weather alerts in 2023, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Grand County and its neighbors
Each county as a circle sized by its count in 2023. Tap one for its archive.
- Alerts
- 91
- Warnings
- 23
- Watches
- 17
- Advisories
- 43
- Busiest month
- February13 alerts
- Busiest day
- March 9, 20233 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Grand County, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 2 | 0 | 100% | 2 | 0% | |
| Flash flood warnings | 7 | 0 | 100% | 1 | 0% |
Each office's whole area, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Denver/Boulder, CO: tornado warnings | 67 | 20 | 70% | 79 | 71% | 13 min |
| NWS Denver/Boulder, CO: severe thunderstorm warnings | 467 | 169 | 64% | 521 | 75% | 18 min |
| NWS Denver/Boulder, CO: flash flood warnings | 80 | 19 | 76% | 35 | 74% | 74 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 1, 3:06 AM MST | Winter Weather Advisory | BOU | 45 hr |
| Jan 9, 2:11 PM MST | Winter Weather Advisory | BOU | 22 hr |
| Jan 10, 2:06 PM MST | Winter Weather Advisory | BOU | 33 hr |
| Jan 16, 12:36 PM MST | Winter Weather Advisory | BOU | 52 hr |
| Jan 25, 2:13 PM MST | Winter Storm Watch | BOU | 12 hr |
| Jan 26, 1:55 AM MST | Winter Storm Warning | BOU | 63 hr |
| Jan 27, 3:06 AM MST | Winter Weather Advisory | BOU | 38 hr |
| Jan 28, 3:14 AM MST | Winter Storm Warning | BOU | 62 hr |
| Jan 29, 8:36 AM MST | Winter Weather Advisory | BOU | 38 hr |
| Feb 5, 1:40 PM MST | Winter Weather Advisory | BOU | 18 hr |
| Feb 8, 5:37 PM MST | Winter Weather Advisory | BOU | 11 hr |
| Feb 8, 5:44 PM MST | Mesoscale Discussion | SPC | 4 hr |
| Feb 14, 2:59 AM MST | Winter Weather Advisory | BOU | 45 hr |
| Feb 18, 2:12 AM MST | High Wind Watch | BOU | 25 hr |
| Feb 18, 2:22 AM MST | Winter Weather Advisory | BOU | 39 hr |
| Feb 19, 3:25 AM MST | High Wind Warning | BOU | 57 hr |
| Feb 20, 2:18 AM MST | Winter Storm Watch | BOU | 26 hr |
| Feb 20, 2:08 PM MST | Winter Storm Warning | BOU | 54 hr |
| Feb 21, 3:50 AM MST | Winter Weather Advisory | BOU | 49 hr |
| Feb 22, 12:48 PM MST | Snow Squall Warning | BOU | 57 min |
| Feb 22, 12:56 PM MST | Snow Squall Warning | BOU | 49 min |
| Feb 25, 2:12 PM MST | Winter Weather Advisory | BOU | 70 hr |
| Mar 3, 1:32 PM MST | Winter Weather Advisory | BOU | 63 hr |
| Mar 9, 2:19 AM MST | Winter Storm Watch | BOU | 13 hr |
| Mar 9, 2:59 PM MST | Winter Storm Warning | BOU | 44 hr |
| Mar 9, 2:59 PM MST | Winter Weather Advisory | BOU | 43 hr |
| Mar 14, 2:56 AM MDT | Winter Weather Advisory | BOU | 57 hr |
| Mar 19, 2:39 PM MDT | Winter Weather Advisory | BOU | 41 hr |
| Mar 20, 2:16 PM MDT | Winter Weather Advisory | BOU | 58 hr |
| Mar 29, 3:25 AM MDT | Winter Weather Advisory | BOU | 63 hr |
| Apr 1, 2:23 PM MDT | Winter Storm Watch | BOU | 23 hr |
| Apr 2, 1:49 PM MDT | Winter Storm Warning | BOU | 58 hr |
| Apr 3, 3:01 AM MDT | Winter Weather Advisory | BOU | 42 hr |
| Apr 13, 2:35 PM MDT | Winter Weather Advisory | BOU | 39 hr |
| Apr 20, 1:22 PM MDT | Winter Weather Advisory | BOU | 46 hr |
| Apr 23, 1:53 PM MDT | Winter Storm Watch | BOU | 24 hr |
| Apr 24, 1:45 PM MDT | Winter Storm Warning | BOU | 39 hr |
| Apr 27, 3:29 AM MDT | Winter Weather Advisory | BOU | 27 hr |
| May 10, 3:08 AM MDT | Flood Watch | BOU | 57 hr |
| May 10, 8:35 PM MDT | Winter Weather Advisory | BOU | 6 hr |
| May 10, 9:02 PM MDT | Winter Storm Watch | BOU | 5 hr |
| May 11, 2:09 AM MDT | Winter Storm Warning | BOU | 32 hr |
| May 12, 9:56 AM MDT | River Flood Advisory | BOU | 6 hr |
| May 22, 6:23 PM MDT | Flash Flood Warning | BOU | 100 min |
| May 23, 5:38 PM MDT | Flash Flood Warning | BOU | 3 hr |
| May 26, 1:16 PM MDT | Areal Flood Advisory | BOU | 6 days |
| Jun 5, 8:42 AM MDT | Flash Flood Watch | BOU | 8 hr |
| Jun 7, 2:35 AM MDT | Flash Flood Watch | BOU | 17 hr |
| Jun 7, 1:55 PM MDT | Flash Flood Warning | BOU | 3 hr |
| Jun 7, 8:08 PM MDT | River Flood Advisory | BOU | 7 days |
| Jun 11, 5:44 PM MDT | Flash Flood Warning | BOU | 3 hr |
| Jun 12, 11:55 AM MDT | Flash Flood Warning | BOU | 3 hr |
| Jun 16, 12:54 PM MDT | Areal Flood Advisory | BOU | 7 days |
| Jun 24, 5:19 PM MDT | Areal Flood Advisory | BOU | 4 days |
| Jun 30, 2:55 PM MDT | Areal Flood Advisory | BOU | 119 min |
| Jul 4, 1:00 PM MDT | Severe Thunderstorm Warning | BOU | 30 min |
| Jul 4, 1:17 PM MDT | Severe Thunderstorm Warning | BOU | 28 min |
| Jul 4, 4:05 PM MDT | Special Weather Statement | BOU | 25 min |
| Jul 4, 6:21 PM MDT | Special Weather Statement | BOU | 39 min |
| Jul 4, 6:36 PM MDT | Areal Flood Advisory | BOU | 3 hr |
| Jul 5, 3:45 PM MDT | Special Weather Statement | BOU | 30 min |
| Jul 5, 8:31 PM MDT | Special Weather Statement | BOU | 44 min |
| Jul 6, 1:37 PM MDT | Mesoscale Discussion | SPC | 113 min |
| Jul 20, 3:59 PM MDT | Flash Flood Warning | BOU | 117 min |
| Jul 26, 1:20 PM MDT | Flash Flood Warning | BOU | 3 hr |
| Jul 27, 9:35 PM MDT | Special Weather Statement | BOU | 40 min |
| Jul 31, 3:11 AM MDT | Flood Watch | BOU | 21 hr |
| Jul 31, 2:37 PM MDT | Flood Watch | BOU | 32 hr |
| Aug 6, 5:16 PM MDT | Areal Flood Advisory | BOU | 119 min |
| Aug 7, 3:49 PM MDT | Areal Flood Advisory | BOU | 40 min |
| Aug 16, 4:39 PM MDT | Special Weather Statement | BOU | 36 min |
| Aug 18, 3:17 PM MDT | Areal Flood Advisory | BOU | 3 hr |
| Aug 24, 1:53 PM MDT | Flood Watch | BOU | 30 hr |
| Aug 26, 5:09 PM MDT | Areal Flood Advisory | BOU | 81 min |
| Sep 3, 5:38 PM MDT | Areal Flood Advisory | BOU | 112 min |
| Sep 15, 5:39 PM MDT | Areal Flood Advisory | BOU | 111 min |
| Oct 10, 2:48 PM MDT | Winter Weather Advisory | BOU | 63 hr |
| Oct 26, 1:51 PM MDT | Winter Storm Watch | BOU | 12 hr |
| Oct 27, 1:53 AM MDT | Winter Storm Warning | BOU | 58 hr |
| Oct 27, 2:22 PM MDT | Winter Weather Advisory | BOU | 46 hr |
| Nov 7, 1:46 PM MST | Winter Weather Advisory | BOU | 34 hr |
| Nov 22, 1:59 PM MST | Winter Weather Advisory | BOU | 63 hr |
| Nov 30, 2:36 PM MST | Winter Storm Watch | BOU | 13 hr |
| Dec 1, 3:16 AM MST | Winter Storm Warning | BOU | 3 days |
| Dec 1, 1:42 PM MST | Winter Weather Advisory | BOU | 63 hr |
| Dec 5, 2:22 PM MST | High Wind Watch | BOU | 23 hr |
| Dec 6, 1:25 PM MST | High Wind Warning | BOU | 28 hr |
| Dec 7, 3:01 AM MST | Winter Weather Advisory | BOU | 50 hr |
| Dec 9, 3:55 AM MST | High Wind Watch | BOU | 9 hr |
| Dec 9, 1:18 PM MST | High Wind Warning | BOU | 28 hr |
| Dec 22, 8:49 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.
| Product | Alerts |
|---|---|
| Severe storms | |
| Severe Thunderstorm Warning | 2 |
| Mesoscale Discussion | 2 |
| Special Weather Statement | 6 |
| Flooding | |
| Flash Flood Warning | 7 |
| Flash Flood Watch | 2 |
| Flood Watch | 4 |
| Areal Flood Advisory | 11 |
| River Flood Advisory | 2 |
| Winter | |
| Snow Squall Warning | 2 |
| Winter Storm Warning | 9 |
| Winter Storm Watch | 8 |
| Winter Weather Advisory | 30 |
| Wind and dust | |
| High Wind Warning | 3 |
| High Wind Watch | 3 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20222024
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.