Alert archive / Colorado / Grand County
Weather alerts in Grand County, Colorado, 2018
70 weather alerts in 2018, 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 2018. Tap one for its archive.
- Alerts
- 70
- Warnings
- 24
- Watches
- 11
- Advisories
- 33
- Busiest month
- February11 alerts
- Busiest day
- April 19, 20183 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, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 2 | 0 | 100% | 0 | ||
| Flash flood warnings | 0 | 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 19, 1:54 PM MST | Winter Storm Watch | BOU | 16 hr |
| Jan 20, 5:24 AM MST | Winter Storm Warning | BOU | 36 hr |
| Jan 20, 5:24 AM MST | Winter Weather Advisory | BOU | 31 hr |
| Jan 25, 2:59 PM MST | Winter Weather Advisory | BOU | 21 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 12, 2:44 PM MST | Winter Weather Advisory | BOU | 15 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 17, 3:26 PM MST | Winter Storm Watch | BOU | 23 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 15, 3:45 AM MDT | Winter Weather Advisory | BOU | 25 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 |
| Mar 28, 4:19 AM MDT | Winter Weather Advisory | BOU | 20 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 11, 3:08 PM MDT | Winter Weather Advisory | BOU | 54 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 |
| May 1, 3:40 AM MDT | Winter Storm Watch | BOU | 12 hr |
| May 1, 3:49 PM MDT | Winter Storm Warning | BOU | 44 hr |
| May 2, 4:56 AM MDT | Winter Weather Advisory | BOU | 31 hr |
| May 18, 3:48 AM MDT | Winter Storm Watch | BOU | 11 hr |
| May 18, 2:29 PM MDT | Winter Weather Advisory | BOU | 13 hr |
| 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 15, 12:35 PM MDT | Red Flag Warning | BOU | 7 hr |
| Jun 26, 2:53 PM MDT | Fire Weather Watch | BOU | 13 hr |
| Jun 27, 3:39 AM MDT | Red Flag Warning | BOU | 42 hr |
| Jun 28, 4:37 AM MDT | Fire Weather Watch | BOU | 10 hr |
| Jun 28, 2:42 PM MDT | Red Flag Warning | BOU | 28 hr |
| Jul 3, 4:03 AM MDT | Red Flag Warning | BOU | 16 hr |
| Jul 23, 1:00 PM MDT | Mesoscale Discussion | SPC | 90 min |
| Jul 25, 5:08 PM MDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 26, 3:35 PM MDT | Red Flag Warning | BOU | 26 hr |
| Aug 30, 3:48 AM MDT | Red Flag Warning | BOU | 15 hr |
| Sep 10, 2:30 PM MDT | Red Flag Warning | BOU | 54 hr |
| Sep 11, 3:06 PM MDT | Red Flag Warning | BOU | 53 hr |
| Sep 23, 3:39 AM MDT | Red Flag Warning | BOU | 16 hr |
| Sep 27, 4:01 PM MDT | Fire Weather Watch | BOU | 19 hr |
| Sep 28, 10:32 AM MDT | Red Flag Warning | BOU | 32 hr |
| Oct 4, 12:22 PM MDT | Severe Thunderstorm Warning | BOU | 38 min |
| Oct 4, 12:52 PM MDT | Severe Thunderstorm Warning | BOU | 38 min |
| 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 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 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 22, 3:49 PM MST | Winter Weather Advisory | BOU | 61 hr |
| Dec 18, 10:08 AM MST | Winter Weather Advisory | BOU | 31 hr |
| Dec 21, 3:50 AM MST | Winter Weather Advisory | BOU | 32 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 |
| Winter | |
| Winter Storm Warning | 7 |
| Winter Storm Watch | 6 |
| Winter Weather Advisory | 33 |
| Wind and dust | |
| High Wind Warning | 3 |
| High Wind Watch | 1 |
| Fire | |
| Red Flag Warning | 12 |
| Fire Weather Watch | 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.