Alert archive / Michigan / Shiawassee County
Weather alerts in Shiawassee County, Michigan, 2017
73 weather alerts in 2017, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Shiawassee County and its neighbors
Each county as a circle sized by its count in 2017. Tap one for its archive.
- Alerts
- 73
- Warnings
- 9
- Watches
- 12
- Advisories
- 24
- Busiest month
- April18 alerts
- Busiest day
- April 6, 20174 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Shiawassee County, 2017
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 3 | 1 | 67% | 1 | 0% | |
| Flash flood warnings | 0 | 0 |
Each office's whole area, 2017
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Detroit, MI: tornado warnings | 3 | 1 | 67% | 4 | 50% | 3 min |
| NWS Detroit, MI: severe thunderstorm warnings | 55 | 35 | 36% | 89 | 76% | 20 min |
| NWS Detroit, MI: flash flood warnings | 4 | 0 | 100% | 0 |
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, Eastern Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jan 3, 12:14 PM EST | Dense Fog Advisory | DTX | 4 hr |
| Jan 9, 3:19 PM EST | Winter Weather Advisory | DTX | 22 hr |
| Jan 10, 3:44 AM EST | High Wind Watch | DTX | 10 hr |
| Jan 10, 2:11 PM EST | High Wind Warning | DTX | 13 hr |
| Jan 10, 5:35 PM EST | Special Weather Statement | DTX | 70 min |
| Jan 11, 7:05 PM EST | Special Weather Statement | DTX | 55 min |
| Jan 12, 6:27 AM EST | Freezing Rain Advisory | DTX | 6 hr |
| Jan 16, 3:35 AM EST | Freezing Rain Advisory | DTX | 27 hr |
| Jan 20, 4:06 PM EST | Dense Fog Advisory | DTX | 20 hr |
| Jan 21, 3:23 PM EST | Dense Fog Advisory | DTX | 36 hr |
| Feb 21, 10:37 PM EST | Dense Fog Advisory | DTX | 11 hr |
| Feb 24, 3:44 PM EST | Severe Thunderstorm Watch | SPC | 6 hr |
| Feb 24, 5:56 PM EST | Mesoscale Discussion | SPC | 94 min |
| Feb 24, 6:10 PM EST | Special Weather Statement | DTX | 50 min |
| Mar 7, 11:25 AM EST | High Wind Watch | DTX | 11 hr |
| Mar 7, 10:14 PM EST | High Wind Warning | DTX | 21 hr |
| Mar 8, 6:56 PM EST | Wind Advisory | DTX | 2 hr |
| Mar 21, 4:52 AM EDT | Dense Fog Advisory | DTX | 4 hr |
| Apr 5, 9:42 AM EDT | Winter Storm Watch | DTX | 251 days |
| Apr 5, 3:00 PM EDT | Flood Watch | DTX | 14 hr |
| Apr 6, 4:28 AM EDT | Winter Storm Warning | DTX | 252 days |
| Apr 6, 4:28 AM EDT | Winter Weather Advisory | DTX | 5 hr |
| Apr 6, 4:47 AM EDT | Wind Advisory | DTX | 23 hr |
| Apr 6, 5:13 AM EDT | River Flood Warning | DTX | 5 days |
| Apr 10, 10:41 AM EDT | Special Weather Statement | DTX | 64 min |
| Apr 10, 3:02 PM EDT | Flood Watch | DTX | 12 hr |
| Apr 10, 8:43 PM EDT | Special Weather Statement | DTX | 62 min |
| Apr 10, 9:24 PM EDT | Special Weather Statement | DTX | 36 min |
| Apr 10, 9:58 PM EDT | Mesoscale Discussion | SPC | 62 min |
| Apr 20, 7:06 AM EDT | Special Weather Statement | DTX | 54 min |
| Apr 20, 9:02 AM EDT | Special Weather Statement | DTX | 43 min |
| Apr 20, 12:39 PM EDT | Special Weather Statement | DTX | 51 min |
| Apr 22, 3:43 PM EDT | Frost Advisory | DTX | 16 hr |
| Apr 26, 11:23 PM EDT | Special Weather Statement | DTX | 67 min |
| Apr 26, 11:26 PM EDT | Severe Thunderstorm Warning | DTX | 47 min |
| Apr 29, 3:14 PM EDT | Flood Watch | DTX | 37 hr |
| May 1, 7:56 AM EDT | Special Weather Statement | DTX | 34 min |
| May 7, 4:03 AM EDT | Freeze Warning | DTX | 28 hr |
| May 8, 2:16 PM EDT | Freeze Warning | DTX | 18 hr |
| May 18, 2:51 AM EDT | Wind Advisory | DTX | 17 hr |
| Jun 5, 7:59 PM EDT | Special Weather Statement | DTX | 61 min |
| Jun 12, 9:09 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 12, 10:30 PM EDT | Mesoscale Discussion | SPC | 90 min |
| Jun 17, 4:54 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 17, 6:55 PM EDT | Special Weather Statement | DTX | 65 min |
| Jun 22, 10:01 PM EDT | Flood Watch | DTX | 8 hr |
| Jul 7, 3:32 AM EDT | Special Weather Statement | DTX | 43 min |
| Jul 7, 3:35 AM EDT | Mesoscale Discussion | SPC | 115 min |
| Jul 10, 8:55 AM EDT | Special Weather Statement | DTX | 65 min |
| Jul 12, 3:51 AM EDT | Flood Watch | DTX | 28 hr |
| Jul 13, 3:19 AM EDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 13, 4:19 AM EDT | Special Weather Statement | DTX | 86 min |
| Jul 13, 4:32 AM EDT | Severe Thunderstorm Warning | DTX | 58 min |
| Aug 3, 6:08 PM EDT | Special Weather Statement | DTX | 67 min |
| Aug 30, 12:10 AM EDT | Dense Fog Advisory | DTX | 10 hr |
| Sep 14, 3:08 AM EDT | Dense Fog Advisory | DTX | 7 hr |
| Sep 21, 3:45 PM EDT | Special Weather Statement | DTX | 45 min |
| Sep 21, 4:50 PM EDT | Special Weather Statement | DTX | 55 min |
| Sep 21, 5:31 PM EDT | Severe Thunderstorm Warning | DTX | 28 min |
| Oct 7, 3:26 PM EDT | Wind Advisory | DTX | 12 hr |
| Oct 7, 9:13 PM EDT | Special Weather Statement | DTX | 77 min |
| Oct 7, 9:35 PM EDT | Special Weather Statement | DTX | 40 min |
| Oct 14, 4:10 AM EDT | Flood Watch | DTX | 17 hr |
| Oct 14, 1:56 PM EDT | Wind Advisory | DTX | 25 hr |
| Oct 15, 11:05 AM EDT | Special Weather Statement | DTX | 55 min |
| Dec 5, 3:57 AM EST | Wind Advisory | DTX | 15 hr |
| Dec 11, 1:29 PM EST | Winter Weather Advisory | DTX | 13 hr |
| Dec 12, 3:48 PM EST | Winter Storm Watch | DTX | 12 hr |
| Dec 21, 7:03 PM EST | Winter Weather Advisory | DTX | 15 hr |
| Dec 25, 4:24 AM EST | Winter Weather Advisory | DTX | 15 hr |
| Dec 25, 3:32 PM EST | Wind Chill Advisory | DTX | 18 hr |
| Dec 26, 2:58 PM EST | Wind Chill Advisory | DTX | 19 hr |
| Dec 30, 2:45 PM EST | Wind Chill Advisory | DTX | 13 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 | 3 |
| Severe Thunderstorm Watch | 2 |
| Mesoscale Discussion | 6 |
| Special Weather Statement | 22 |
| Flooding | |
| River Flood Warning | 1 |
| Flood Watch | 6 |
| Winter | |
| Winter Storm Warning | 1 |
| Winter Storm Watch | 2 |
| Freezing Rain Advisory | 2 |
| Winter Weather Advisory | 5 |
| Cold | |
| Freeze Warning | 2 |
| Frost Advisory | 1 |
| Wind Chill Advisory | 3 |
| Wind and dust | |
| High Wind Warning | 2 |
| High Wind Watch | 2 |
| Wind Advisory | 6 |
| Fog and smoke | |
| Dense Fog Advisory | 7 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20162018
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.