THE CLIMATE OF MICHIGAN. 



703 



Tornadoes occur iufrequeutly in Michigau, on the average about one 

 or two per j'^ear in the entire state. They are practically unknown in 

 the upper peninsula. The region of most frequent occurrence is in the 

 south-central portion of the state. The Great Lakes undoubtedly de- 

 crease the number somewhat, on account of tlieir cooling effect, thereby 

 checking the required convection. These destructive local storms occur 

 usually in the southeastern portion of the larger disturbance, or cyclone, 

 and as the state is in the path of greatest frequency of these cyclones, it 



CHART XI. -Average date of last killing frost in Spring 



seems reasonable to suppose that tornadoes would be more frequent in 

 Michigan than in other states outside the path of storms, were it not for 

 the Great Lakes. 



Notable tornadoes, in recent years, were two which occurred in 1911 

 and 1915 respectivel3^ Tlie first passed through the city of Owosso, doing 

 considerable damage and causing some loss of life. The second passed 

 southwestward from the city limits of Charlotte, Mich., passing two 

 miles north of Eaton Rapids, to some inland lakes southeast of Stock- 

 bridge, Mich., where it disappeared. This storm was of unusual severity 



