Spring storms are returning to the Midwest.
Warm air meeting cold air is often used as an explanation for how tornadoes form, but that's a "gross oversimplification" according to Roger Edwards of the National Weather Service's Storm Prediction Center.
That's how many thunderstorms form, but most of those storms don't turn into tornadoes. Edwards writes, "the truth is that we don't fully understand [how tornadoes form]."
Tornado formation is believed to be dictated mainly by things which happen on the storm scale, in and around the mesocyclone. Recent theories and results from the VORTEX program suggest that once a mesocyclone is underway, tornado development is related to the temperature differences across the edge of downdraft air wrapping around the mesocyclone (the occlusion downdraft).
Last year, there were six tornadoes across Michigan, including the F3 tornado that hit Dexter. Remember that one? These guys probably remember.
But on the whole, 2012 was a below average year for tornadoes in Michigan. Our average is 15 a year.
We know this because the National Weather Service has records of tornadoes dating back to 1950.
Over that period of time, we've had 968 tornadoes in Michigan—most concentrated in the southern part of the state:
From 1950 to 2012, the counties in Michigan that experienced the most tornado activity were:
- Genesee 41
- Monroe 33
- Lenawee 32
- Berrien 31
- Kent 31
- Oakland 31
- Allegan 29
- Wayne 29
- Ingham 28
- Washtenaw 27
Tornadoes do hit Michigan, but we're hardly in tornado alley.
Greg Carbin from NOAA Storm Prediction Center says Michigan ranks 25th in the nation in the number of tornadoes it gets.
From this map, you can see where tornado activity has been highest over the last 20 years:
*this post has been updated