Alert archive / Colorado / San Juan County
Weather alerts in San Juan County, Colorado, 2021
83 weather alerts in 2021, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
San Juan County and its neighbors
Each county as a circle sized by its count in 2021. Tap one for its archive.
- Alerts
- 83
- Warnings
- 31
- Watches
- 30
- Advisories
- 16
- Busiest month
- April20 alerts
- Busiest day
- June 17, 20213 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
San Juan County, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 0 | 0 | ||||
| Flash flood warnings | 2 | 0 | 100% | 0 |
Each office's whole area, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Grand Junction, CO: severe thunderstorm warnings | 28 | 3 | 89% | 29 | 10% | 27 min |
| NWS Grand Junction, CO: flash flood warnings | 85 | 20 | 76% | 51 | 49% | 51 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 17, 1:57 PM MST | Winter Weather Advisory | GJT | 24 hr |
| Jan 18, 1:40 PM MST | Winter Storm Warning | GJT | 27 hr |
| Jan 21, 2:00 PM MST | Winter Weather Advisory | GJT | 4 days |
| Jan 25, 3:35 AM MST | Winter Weather Advisory | GJT | 37 hr |
| Jan 29, 3:33 AM MST | Winter Weather Advisory | GJT | 28 hr |
| Feb 2, 3:33 AM MST | Winter Weather Advisory | GJT | 52 hr |
| Feb 12, 3:10 AM MST | Winter Storm Watch | GJT | 11 hr |
| Feb 12, 2:14 PM MST | Winter Storm Warning | GJT | 51 hr |
| Feb 14, 2:13 PM MST | Winter Weather Advisory | GJT | 51 hr |
| Mar 3, 3:10 AM MST | Winter Weather Advisory | GJT | 34 hr |
| Mar 11, 3:22 AM MST | Winter Storm Watch | GJT | 24 hr |
| Mar 12, 3:47 AM MST | Winter Weather Advisory | GJT | 3 days |
| Mar 22, 2:43 PM MDT | Winter Weather Advisory | GJT | 51 hr |
| Mar 24, 9:35 PM MDT | Winter Weather Advisory | GJT | 40 hr |
| Apr 5, 2:20 PM MDT | Red Flag Warning | GJT | 28 hr |
| Apr 6, 2:09 PM MDT | Red Flag Warning | GJT | 30 hr |
| Apr 7, 2:20 PM MDT | Red Flag Warning | GJT | 31 hr |
| Apr 8, 2:28 AM MDT | Red Flag Warning | GJT | 43 hr |
| Apr 9, 9:01 PM MDT | Fire Weather Watch | GJT | 5 hr |
| Apr 10, 1:57 AM MDT | Red Flag Warning | GJT | 42 hr |
| Apr 13, 2:27 PM MDT | Red Flag Warning | GJT | 31 hr |
| Apr 14, 2:33 AM MDT | Fire Weather Watch | GJT | 12 hr |
| Apr 14, 2:12 PM MDT | Red Flag Warning | GJT | 29 hr |
| Apr 16, 2:16 PM MDT | Winter Weather Advisory | GJT | 31 hr |
| Apr 18, 3:44 AM MDT | Red Flag Warning | GJT | 41 hr |
| Apr 19, 2:21 PM MDT | Fire Weather Watch | GJT | 13 hr |
| Apr 20, 3:12 AM MDT | Red Flag Warning | GJT | 18 hr |
| Apr 20, 3:12 AM MDT | Red Flag Warning | GJT | 43 hr |
| Apr 22, 2:24 PM MDT | Fire Weather Watch | GJT | 12 hr |
| Apr 22, 2:24 PM MDT | Fire Weather Watch | GJT | 39 hr |
| Apr 23, 2:44 AM MDT | Red Flag Warning | GJT | 41 hr |
| Apr 23, 2:35 PM MDT | Red Flag Warning | GJT | 57 hr |
| Apr 25, 4:38 AM MDT | Fire Weather Watch | GJT | 4 hr |
| Apr 25, 9:06 AM MDT | Red Flag Warning | GJT | 35 hr |
| May 19, 3:21 AM MDT | Fire Weather Watch | GJT | 11 hr |
| May 19, 2:39 PM MDT | Red Flag Warning | GJT | 32 hr |
| May 21, 10:21 AM MDT | Winter Weather Advisory | GJT | 14 hr |
| May 31, 12:47 PM MDT | Mesoscale Discussion | SPC | 88 min |
| Jun 7, 3:17 AM MDT | Red Flag Warning | GJT | 42 hr |
| Jun 7, 2:35 PM MDT | Fire Weather Watch | GJT | 20 hr |
| Jun 8, 10:22 AM MDT | Red Flag Warning | GJT | 62 hr |
| Jun 17, 3:42 AM MDT | Fire Weather Watch | GJT | 11 hr |
| Jun 17, 2:41 PM MDT | Fire Weather Watch | GJT | 24 hr |
| Jun 17, 2:41 PM MDT | Red Flag Warning | GJT | 30 hr |
| Jun 18, 2:34 PM MDT | Red Flag Warning | GJT | 30 hr |
| Jun 20, 2:17 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jun 21, 3:18 AM MDT | Fire Weather Watch | GJT | 11 hr |
| Jun 22, 2:41 PM MDT | Red Flag Warning | GJT | 30 hr |
| Jul 13, 12:50 PM MDT | Special Weather Statement | GJT | 25 min |
| Jul 13, 1:28 PM MDT | Special Weather Statement | GJT | 47 min |
| Jul 14, 2:19 AM MDT | Flash Flood Watch | GJT | 18 hr |
| Jul 20, 2:50 PM MDT | Flash Flood Warning | GJT | 5 hr |
| Jul 20, 3:19 PM MDT | Areal Flood Warning | GJT | 2 min |
| Jul 20, 3:21 PM MDT | Flash Flood Warning | GJT | 3 hr |
| Jul 21, 2:42 AM MDT | Flash Flood Watch | GJT | 21 hr |
| Jul 21, 1:44 PM MDT | Flash Flood Watch | GJT | 34 hr |
| Jul 22, 1:50 PM MDT | Flash Flood Watch | GJT | 36 hr |
| Jul 23, 2:17 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jul 23, 4:57 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jul 24, 3:51 AM MDT | Flash Flood Watch | GJT | 17 hr |
| Jul 28, 2:28 PM MDT | Flash Flood Watch | GJT | 34 hr |
| Jul 28, 2:28 PM MDT | Flash Flood Watch | GJT | 58 hr |
| Jul 30, 3:44 AM MDT | Flash Flood Watch | GJT | 43 hr |
| Aug 1, 3:05 AM MDT | Flash Flood Watch | GJT | 18 hr |
| Aug 1, 1:25 PM MDT | Flash Flood Watch | GJT | 35 hr |
| Aug 2, 2:30 PM MDT | Flash Flood Watch | GJT | 29 hr |
| Aug 19, 4:36 PM MDT | Special Weather Statement | GJT | 24 min |
| Aug 30, 2:17 PM MDT | Flash Flood Watch | GJT | 58 hr |
| Oct 10, 2:15 PM MDT | Winter Storm Watch | GJT | 14 hr |
| Oct 11, 3:46 AM MDT | Winter Weather Advisory | GJT | 50 hr |
| Oct 11, 2:34 PM MDT | Winter Storm Warning | GJT | 33 hr |
| Oct 25, 3:02 AM MDT | Winter Weather Advisory | GJT | 45 hr |
| Dec 7, 2:56 PM MST | Winter Storm Watch | GJT | 21 hr |
| Dec 8, 12:16 PM MST | Winter Storm Warning | GJT | 54 hr |
| Dec 13, 4:20 AM MST | Winter Storm Watch | GJT | 10 hr |
| Dec 13, 2:31 PM MST | Winter Storm Warning | GJT | 47 hr |
| Dec 15, 3:51 AM MST | Special Weather Statement | GJT | 39 min |
| Dec 15, 4:35 AM MST | Special Weather Statement | GJT | 40 min |
| Dec 22, 3:34 AM MST | Winter Storm Warning | GJT | 3 days |
| Dec 25, 2:59 AM MST | Winter Storm Watch | GJT | 12 hr |
| Dec 25, 2:59 PM MST | Winter Storm Warning | GJT | 4 days |
| Dec 28, 1:48 PM MST | Winter Storm Watch | GJT | 25 hr |
| Dec 29, 2:53 PM MST | Winter Storm Warning | GJT | 72 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 | |
| Mesoscale Discussion | 1 |
| Special Weather Statement | 5 |
| Flooding | |
| Areal Flood Warning | 1 |
| Flash Flood Warning | 2 |
| Flash Flood Watch | 12 |
| Areal Flood Advisory | 2 |
| Winter | |
| Winter Storm Warning | 8 |
| Winter Storm Watch | 7 |
| Winter Weather Advisory | 14 |
| Fire | |
| Red Flag Warning | 20 |
| Fire Weather Watch | 11 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20202022
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.