Alert archive / Utah / San Juan County
Weather alerts in San Juan County, Utah, 2020
121 weather alerts in 2020, 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 2020. Tap one for its archive.
- Alerts
- 121
- Warnings
- 61
- Watches
- 28
- Advisories
- 25
- Busiest month
- June46 alerts
- Busiest day
- June 6, 202017 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, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 9 | 5 | 44% | 11 | 73% | 27 min |
| Flash flood warnings | 3 | 1 | 67% | 1 | 100% | 12 min |
Each office's whole area, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Grand Junction, CO: severe thunderstorm warnings | 45 | 22 | 51% | 96 | 35% | 20 min |
| NWS Grand Junction, CO: flash flood warnings | 3 | 2 | 33% | 6 | 50% | 40 min |
| NWS Salt Lake City, UT: severe thunderstorm warnings | 34 | 19 | 44% | 93 | 40% | 17 min |
| NWS Salt Lake City, UT: flash flood warnings | 21 | 10 | 52% | 18 | 83% | 77 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 4, 11:18 PM MST | Dense Fog Advisory | GJT | 10 hr |
| Jan 10, 2:20 PM MST | Winter Weather Advisory | GJT | 3 days |
| Jan 21, 9:47 PM MST | Dense Fog Advisory | GJT | 15 hr |
| Feb 2, 9:45 PM MST | Wind Advisory | GJT | 16 hr |
| Feb 21, 3:22 AM MST | Winter Weather Advisory | GJT | 59 hr |
| Mar 11, 3:00 AM MDT | Winter Storm Watch | GJT | 35 hr |
| Mar 12, 2:07 PM MDT | Winter Weather Advisory | GJT | 34 hr |
| Mar 17, 2:29 PM MDT | Winter Weather Advisory | GJT | 64 hr |
| May 15, 3:25 PM MDT | Red Flag Warning | SLC | 4 days |
| May 18, 2:42 PM MDT | Wind Advisory | GJT | 30 hr |
| May 21, 10:55 AM MDT | Red Flag Warning | SLC | 34 hr |
| May 27, 2:49 PM MDT | Fire Weather Watch | SLC | 24 hr |
| May 28, 3:05 PM MDT | Red Flag Warning | SLC | 4 days |
| May 29, 2:25 PM MDT | Fire Weather Watch | GJT | 24 hr |
| Jun 3, 1:03 PM MDT | Fire Weather Watch | SLC | 23 hr |
| Jun 4, 2:41 AM MDT | Red Flag Warning | GJT | 41 hr |
| Jun 4, 12:24 PM MDT | Red Flag Warning | SLC | 33 hr |
| Jun 5, 3:42 AM MDT | Flash Flood Watch | GJT | 36 hr |
| Jun 5, 2:46 PM MDT | Fire Weather Watch | GJT | 24 hr |
| Jun 5, 6:39 PM MDT | Special Weather Statement | GJT | 51 min |
| Jun 6, 2:16 AM MDT | Wind Advisory | GJT | 18 hr |
| Jun 6, 7:01 AM MDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 6, 8:59 AM MDT | Special Weather Statement | GJT | 31 min |
| Jun 6, 9:07 AM MDT | Special Weather Statement | SLC | 23 min |
| Jun 6, 9:29 AM MDT | Severe Thunderstorm Warning | GJT | 31 min |
| Jun 6, 9:38 AM MDT | Flash Flood Warning | GJT | 3 hr |
| Jun 6, 9:39 AM MDT | Severe Thunderstorm Warning | GJT | 36 min |
| Jun 6, 9:48 AM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 6, 9:54 AM MDT | Severe Thunderstorm Warning | GJT | 36 min |
| Jun 6, 10:09 AM MDT | Severe Thunderstorm Warning | GJT | 36 min |
| Jun 6, 10:24 AM MDT | Severe Thunderstorm Warning | GJT | 36 min |
| Jun 6, 10:33 AM MDT | Severe Thunderstorm Warning | GJT | 42 min |
| Jun 6, 10:53 AM MDT | Severe Thunderstorm Warning | GJT | 22 min |
| Jun 6, 11:18 AM MDT | Severe Thunderstorm Warning | GJT | 27 min |
| Jun 6, 11:24 AM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jun 6, 2:36 PM MDT | Red Flag Warning | GJT | 31 hr |
| Jun 6, 8:09 PM MDT | Wind Advisory | GJT | 24 hr |
| Jun 6, 8:49 PM MDT | Red Flag Warning | SLC | 24 hr |
| Jun 7, 1:46 PM MDT | Red Flag Warning | GJT | 30 hr |
| Jun 7, 3:08 PM MDT | Red Flag Warning | SLC | 29 hr |
| Jun 10, 4:20 AM MDT | Fire Weather Watch | SLC | 23 hr |
| Jun 11, 3:18 AM MDT | Red Flag Warning | SLC | 66 hr |
| Jun 11, 2:39 PM MDT | Fire Weather Watch | GJT | 37 hr |
| Jun 12, 1:57 AM MDT | Red Flag Warning | GJT | 44 hr |
| Jun 13, 3:37 AM MDT | Wind Advisory | GJT | 16 hr |
| Jun 13, 3:46 AM MDT | Fire Weather Watch | GJT | 41 hr |
| Jun 13, 3:46 AM MDT | Red Flag Warning | GJT | 40 hr |
| Jun 13, 1:48 PM MDT | Special Weather Statement | GJT | 42 min |
| Jun 13, 2:23 PM MDT | Fire Weather Watch | SLC | 22 hr |
| Jun 13, 2:40 PM MDT | Fire Weather Watch | GJT | 48 hr |
| Jun 14, 12:51 PM MDT | Red Flag Warning | SLC | 56 hr |
| Jun 14, 2:27 PM MDT | Red Flag Warning | GJT | 31 hr |
| Jun 14, 2:27 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jun 16, 3:02 AM MDT | Red Flag Warning | GJT | 41 hr |
| Jun 17, 9:18 AM MDT | Red Flag Warning | SLC | 11 hr |
| Jun 25, 2:19 PM MDT | Fire Weather Watch | SLC | 24 hr |
| Jun 26, 1:55 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jun 26, 2:33 PM MDT | Red Flag Warning | SLC | 3 days |
| Jun 27, 2:22 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jun 27, 2:22 PM MDT | Wind Advisory | GJT | 51 hr |
| Jul 2, 2:03 PM MDT | Red Flag Warning | SLC | 31 hr |
| Jul 4, 2:26 PM MDT | Fire Weather Watch | GJT | 23 hr |
| Jul 4, 2:26 PM MDT | Fire Weather Watch | SLC | 22 hr |
| Jul 5, 12:19 PM MDT | Red Flag Warning | SLC | 60 hr |
| Jul 5, 1:52 PM MDT | Fire Weather Watch | GJT | 25 hr |
| Jul 5, 1:52 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jul 5, 1:57 PM MDT | Fire Weather Watch | SLC | 24 hr |
| Jul 6, 2:19 PM MDT | Red Flag Warning | SLC | 55 hr |
| Jul 6, 2:23 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jul 9, 7:59 AM MDT | Red Flag Warning | SLC | 13 hr |
| Jul 9, 3:25 PM MDT | Heat Advisory | GJT | 4 days |
| Jul 10, 2:20 PM MDT | Fire Weather Watch | SLC | 24 hr |
| Jul 11, 3:19 AM MDT | Fire Weather Watch | GJT | 11 hr |
| Jul 11, 2:12 PM MDT | Red Flag Warning | GJT | 55 hr |
| Jul 11, 2:16 PM MDT | Red Flag Warning | SLC | 3 days |
| Jul 12, 2:08 AM MDT | Fire Weather Watch | GJT | 12 hr |
| Jul 12, 1:48 PM MDT | Red Flag Warning | GJT | 54 hr |
| Jul 19, 3:15 PM MDT | Fire Weather Watch | SLC | 23 hr |
| Jul 20, 2:00 PM MDT | Red Flag Warning | SLC | 31 hr |
| Jul 22, 6:45 PM MDT | Severe Thunderstorm Warning | SLC | 30 min |
| Jul 22, 7:20 PM MDT | Special Weather Statement | GJT | 40 min |
| Jul 23, 3:45 PM MDT | Flash Flood Warning | SLC | 3 hr |
| Jul 23, 5:23 PM MDT | Areal Flood Advisory | GJT | 48 min |
| Jul 23, 6:11 PM MDT | Flash Flood Warning | GJT | 2 hr |
| Jul 26, 5:58 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jul 27, 2:29 PM MDT | Areal Flood Advisory | GJT | 2 hr |
| Jul 27, 3:14 PM MDT | Areal Flood Advisory | GJT | 106 min |
| Jul 27, 5:42 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jul 27, 6:24 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Aug 2, 2:10 PM MDT | Red Flag Warning | SLC | 32 hr |
| Aug 3, 2:25 PM MDT | Fire Weather Watch | SLC | 13 hr |
| Aug 4, 3:21 AM MDT | Red Flag Warning | SLC | 66 hr |
| Aug 4, 2:31 PM MDT | Red Flag Warning | GJT | 53 hr |
| Aug 10, 3:21 AM MDT | Fire Weather Watch | SLC | 11 hr |
| Aug 10, 2:14 PM MDT | Red Flag Warning | SLC | 3 days |
| Aug 10, 2:40 PM MDT | Red Flag Warning | GJT | 29 hr |
| Aug 11, 2:05 PM MDT | Red Flag Warning | GJT | 30 hr |
| Aug 18, 9:12 AM MDT | Heat Advisory | GJT | 36 hr |
| Aug 22, 2:56 AM MDT | Red Flag Warning | SLC | 42 hr |
| Aug 27, 9:35 PM MDT | Special Weather Statement | GJT | 40 min |
| Aug 28, 2:54 PM MDT | Red Flag Warning | SLC | 3 days |
| Aug 30, 2:23 AM MDT | Red Flag Warning | GJT | 43 hr |
| Sep 4, 2:43 PM MDT | Fire Weather Watch | SLC | 48 hr |
| Sep 4, 2:43 PM MDT | Red Flag Warning | SLC | 4 days |
| Sep 15, 2:00 PM MDT | Fire Weather Watch | SLC | 48 hr |
| Sep 16, 2:49 PM MDT | Red Flag Warning | SLC | 3 days |
| Sep 23, 11:34 AM MDT | Red Flag Warning | SLC | 3 days |
| Sep 23, 2:41 PM MDT | Fire Weather Watch | SLC | 24 hr |
| Sep 24, 3:00 AM MDT | Red Flag Warning | GJT | 41 hr |
| Oct 9, 2:34 PM MDT | Red Flag Warning | SLC | 54 hr |
| Oct 20, 2:36 PM MDT | Red Flag Warning | SLC | 54 hr |
| Oct 21, 2:28 PM MDT | Fire Weather Watch | GJT | 11 hr |
| Oct 22, 1:40 AM MDT | Red Flag Warning | GJT | 16 hr |
| Oct 22, 3:15 PM MDT | Red Flag Warning | SLC | 54 hr |
| Oct 24, 10:11 AM MDT | Freeze Warning | GJT | 50 hr |
| Oct 24, 3:10 PM MDT | Fire Weather Watch | SLC | 12 hr |
| Oct 24, 8:45 PM MDT | Winter Weather Advisory | GJT | 45 hr |
| Oct 25, 3:02 AM MDT | Red Flag Warning | SLC | 42 hr |
| Nov 6, 7:39 PM MST | Wind Advisory | GJT | 32 hr |
| Nov 8, 3:23 AM MST | Winter Weather Advisory | GJT | 44 hr |
| Dec 11, 3:20 AM MST | Winter Weather Advisory | GJT | 48 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 | 9 |
| Severe Thunderstorm Watch | 1 |
| Mesoscale Discussion | 1 |
| Special Weather Statement | 6 |
| Flooding | |
| Flash Flood Warning | 3 |
| Flash Flood Watch | 1 |
| Areal Flood Advisory | 7 |
| Winter | |
| Winter Storm Watch | 1 |
| Winter Weather Advisory | 7 |
| Heat | |
| Heat Advisory | 2 |
| Cold | |
| Freeze Warning | 1 |
| Wind and dust | |
| Wind Advisory | 7 |
| Fire | |
| Red Flag Warning | 48 |
| Fire Weather Watch | 25 |
| Fog and smoke | |
| Dense Fog Advisory | 2 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20192021
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.