Alert archive / Utah / San Juan County
Weather alerts in San Juan County, Utah, 2009
59 weather alerts in 2009, 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 2009. Tap one for its archive.
- Alerts
- 59
- Warnings
- 15
- Watches
- 12
- Advisories
- 29
- Busiest month
- December11 alerts
- Busiest day
- May 25, 20093 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 1 tornado reports fell inside a warning.
San Juan County, 2009
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 1 | 0% | |||
| Severe thunderstorm warnings | 4 | 0 | 100% | 2 | 0% | |
| Flash flood warnings | 1 | 0 | 100% | 0 |
Each office's whole area, 2009
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Grand Junction, CO: tornado warnings | 0 | 2 | 0% | |||
| NWS Grand Junction, CO: severe thunderstorm warnings | 29 | 8 | 72% | 25 | 60% | 18 min |
| NWS Grand Junction, CO: flash flood warnings | 11 | 1 | 91% | 2 | 50% | 0 min |
| NWS Salt Lake City, UT: tornado warnings | 0 | 2 | 0% | |||
| NWS Salt Lake City, UT: severe thunderstorm warnings | 79 | 10 | 87% | 63 | 24% | 19 min |
| NWS Salt Lake City, UT: flash flood warnings | 11 | 4 | 64% | 7 | 57% | 57 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 25, 3:57 AM MST | Winter Weather Advisory | GJT | 58 hr |
| Feb 6, 4:00 AM MST | Winter Storm Watch | GJT | 22 hr |
| Feb 7, 2:23 AM MST | Winter Weather Advisory | GJT | 52 hr |
| Feb 8, 3:06 PM MST | Winter Weather Advisory | GJT | 48 hr |
| Feb 9, 10:35 AM MST | Winter Storm Warning | GJT | 29 hr |
| Mar 22, 3:43 PM MDT | Wind Advisory | GJT | 5 hr |
| Mar 24, 3:32 PM MDT | Winter Storm Watch | GJT | 23 hr |
| Mar 25, 2:47 PM MDT | Winter Weather Advisory | GJT | 43 hr |
| Mar 28, 3:12 PM MDT | High Wind Watch | GJT | 13 hr |
| Mar 29, 4:30 AM MDT | Wind Advisory | GJT | 18 hr |
| Mar 29, 11:17 AM MDT | High Wind Warning | GJT | 11 hr |
| Apr 2, 3:45 PM MDT | Winter Weather Advisory | GJT | 56 hr |
| Apr 3, 3:29 AM MDT | Wind Advisory | GJT | 18 hr |
| Apr 8, 12:39 AM MDT | Wind Advisory | GJT | 20 hr |
| Apr 10, 3:36 PM MDT | Winter Weather Advisory | GJT | 50 hr |
| Apr 15, 8:37 AM MDT | Wind Advisory | GJT | 11 hr |
| Apr 25, 4:19 AM MDT | Wind Advisory | GJT | 17 hr |
| May 22, 5:41 PM MDT | Areal Flood Advisory | GJT | 4 hr |
| May 22, 6:14 PM MDT | Areal Flood Advisory | SLC | 4 hr |
| May 24, 2:01 AM MDT | Flash Flood Watch | GJT | 20 hr |
| May 25, 3:58 AM MDT | Flash Flood Watch | GJT | 16 hr |
| May 25, 11:55 AM MDT | Flash Flood Warning | GJT | 6 hr |
| May 25, 3:02 PM MDT | Areal Flood Advisory | GJT | 4 hr |
| May 29, 7:04 PM MDT | Severe Thunderstorm Warning | SLC | 41 min |
| Jun 5, 3:56 AM MDT | Wind Advisory | GJT | 17 hr |
| Jun 26, 8:29 AM MDT | Flash Flood Watch | GJT | 12 hr |
| Jun 26, 3:14 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jun 26, 4:22 PM MDT | Special Weather Statement | SLC | 23 min |
| Jul 11, 3:56 PM MDT | Areal Flood Advisory | GJT | 2 hr |
| Jul 11, 5:46 PM MDT | Areal Flood Advisory | GJT | 104 min |
| Jul 26, 12:02 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jul 26, 12:18 PM MDT | Areal Flood Advisory | GJT | 3 hr |
| Jul 28, 1:55 PM MDT | Mesoscale Discussion | SPC | 65 min |
| Jul 28, 3:13 PM MDT | Severe Thunderstorm Warning | GJT | 47 min |
| Jul 29, 2:58 PM MDT | Severe Thunderstorm Warning | SLC | 32 min |
| Sep 14, 12:38 PM MDT | Severe Thunderstorm Warning | GJT | 52 min |
| Sep 15, 12:46 PM MDT | Mesoscale Discussion | SPC | 89 min |
| Sep 30, 3:47 AM MDT | Freeze Watch | GJT | 11 hr |
| Sep 30, 3:47 AM MDT | Wind Advisory | GJT | 16 hr |
| Sep 30, 2:55 PM MDT | Freeze Warning | GJT | 18 hr |
| Oct 1, 7:22 PM MDT | Freeze Warning | GJT | 14 hr |
| Oct 3, 3:09 PM MDT | Wind Advisory | GJT | 30 hr |
| Oct 20, 2:02 PM MDT | Areal Flood Advisory | GJT | 78 min |
| Oct 25, 4:30 AM MDT | Freeze Watch | GJT | 10 hr |
| Oct 25, 2:56 PM MDT | Freeze Warning | GJT | 18 hr |
| Oct 26, 3:52 PM MDT | Winter Storm Warning | GJT | 3 days |
| Oct 27, 5:13 AM MDT | Winter Weather Advisory | GJT | 48 hr |
| Nov 12, 4:48 AM MST | Winter Weather Advisory | GJT | 3 days |
| Dec 5, 4:26 AM MST | Blizzard Watch | GJT | 12 hr |
| Dec 5, 4:26 AM MST | Winter Storm Watch | GJT | 45 hr |
| Dec 5, 4:07 PM MST | Blizzard Warning | GJT | 71 hr |
| Dec 6, 2:20 PM MST | Winter Storm Warning | GJT | 49 hr |
| Dec 11, 3:06 PM MST | Winter Storm Watch | GJT | 13 hr |
| Dec 12, 4:05 AM MST | Winter Weather Advisory | GJT | 53 hr |
| Dec 21, 3:05 AM MST | Winter Storm Watch | GJT | 12 hr |
| Dec 21, 3:08 PM MST | Winter Weather Advisory | GJT | 63 hr |
| Dec 21, 10:39 PM MST | Winter Storm Warning | GJT | 37 hr |
| Dec 29, 3:13 PM MST | Winter Weather Advisory | GJT | 37 hr |
| Dec 30, 4:16 AM MST | Winter Storm Warning | GJT | 24 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 | 4 |
| Mesoscale Discussion | 2 |
| Special Weather Statement | 1 |
| Flooding | |
| Flash Flood Warning | 1 |
| Flash Flood Watch | 3 |
| Areal Flood Advisory | 9 |
| Winter | |
| Blizzard Warning | 1 |
| Winter Storm Warning | 5 |
| Blizzard Watch | 1 |
| Winter Storm Watch | 5 |
| Winter Weather Advisory | 11 |
| Cold | |
| Freeze Warning | 3 |
| Freeze Watch | 2 |
| Wind and dust | |
| High Wind Warning | 1 |
| High Wind Watch | 1 |
| Wind Advisory | 9 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20082010
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.