Weather alerts in Michigan, 2018
2,814 weather alerts in 2018, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered any part of the state, so the counties below add up to more than the state.
Weather alerts by county
Each county as a circle sized by its count in 2018. Tap one for its archive.
- Alerts
- 2,814
- Warnings
- 842
- Watches
- 144
- Advisories
- 888
- Busiest month
- August463 alerts
- Busiest day
- July 1, 201873 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
4 of 14 tornado warnings covering Michigan in 2018 had a tornado report inside them; 5 of 14 tornado reports fell inside a warning, on average 10 minutes after it went out.
Michigan, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 14 | 4 | 71% | 14 | 36% | 10 min |
| Severe thunderstorm warnings | 253 | 138 | 45% | 365 | 71% | 21 min |
| Flash flood warnings | 18 | 5 | 72% | 32 | 84% | 218 min |
Each office's whole area, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Green Bay, WI: tornado warnings | 9 | 2 | 78% | 4 | 50% | 4 min |
| NWS Green Bay, WI: severe thunderstorm warnings | 73 | 42 | 42% | 130 | 68% | 22 min |
| NWS Green Bay, WI: flash flood warnings | 3 | 2 | 33% | 3 | 67% | 41 min |
| NWS Grand Rapids, MI: tornado warnings | 3 | 1 | 67% | 6 | 17% | 12 min |
| NWS Grand Rapids, MI: severe thunderstorm warnings | 58 | 35 | 40% | 112 | 71% | 22 min |
| NWS Northern Indiana: tornado warnings | 6 | 2 | 67% | 6 | 33% | 2 min |
| NWS Northern Indiana: severe thunderstorm warnings | 93 | 34 | 63% | 187 | 41% | 19 min |
| NWS Northern Indiana: flash flood warnings | 9 | 2 | 78% | 4 | 75% | 59 min |
| NWS Detroit, MI: tornado warnings | 6 | 2 | 67% | 3 | 100% | 12 min |
| NWS Detroit, MI: severe thunderstorm warnings | 54 | 34 | 37% | 80 | 76% | 18 min |
| NWS Detroit, MI: flash flood warnings | 2 | 0 | 100% | 0 | ||
| NWS Marquette, MI: tornado warnings | 2 | 0 | 100% | 0 | ||
| NWS Marquette, MI: severe thunderstorm warnings | 65 | 23 | 65% | 75 | 69% | 22 min |
| NWS Marquette, MI: flash flood warnings | 10 | 5 | 50% | 31 | 87% | 218 min |
| NWS Gaylord, MI: tornado warnings | 3 | 1 | 67% | 5 | 20% | 1 min |
| NWS Gaylord, MI: severe thunderstorm warnings | 45 | 30 | 33% | 70 | 79% | 22 min |
| NWS Gaylord, 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
2,814 alerts are too many to list on one page. Narrow it to a product above, to a month in the chart, or to a county.
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Monroe County126
- Wayne County125
- Marquette County120
- Allegan County108
- Kalamazoo County108
- Menominee County107
- Cass County107
- Ingham County106
- Jackson County105
- Houghton County105
- Kent County103
- Van Buren County103
- Saint Joseph County103
- Oakland County103
- Barry County101
- Calhoun County100
- Branch County100
- Washtenaw County97
- Gogebic County97
- Saint Clair County97
- Lenawee County96
- Livingston County95
- Dickinson County94
- Eaton County93
- Ionia County93
- Muskegon County90
- Ottawa County90
- Macomb County90
- Hillsdale County89
- Clinton County89
- Alger County86
- Bay County85
- Ontonagon County84
- Schoolcraft County84
- Saginaw County84
- Genesee County83
- Huron County82
- Isabella County81
- Baraga County80
- Delta County80
43 more counties
- Oceana County78
- Mason County77
- Midland County76
- Sanilac County76
- Tuscola County76
- Newaygo County74
- Antrim County74
- Cheboygan County73
- Shiawassee County72
- Kalkaska County71
- Gratiot County71
- Mecosta County70
- Montcalm County69
- Lake County68
- Emmet County68
- Alpena County68
- Iron County66
- Alcona County66
- Crawford County66
- Oscoda County66
- Otsego County66
- Arenac County65
- Iosco County65
- Missaukee County63
- Ogemaw County63
- Roscommon County63
- Lapeer County63
- Manistee County62
- Montmorency County62
- Clare County62
- Gladwin County61
- Grand Traverse County60
- Osceola County60
- Benzie County59
- Wexford County59
- Leelanau County58
- Presque Isle County56
- Keweenaw County53
- Berrien County49
- Luce County48
- Charlevoix County19
- Chippewa County16
- Mackinac County15
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe 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.