FLOODS BROOKS AND THIESSEN" 339 



Dayton, 17 feet in one day, was mainly responsible for the large loss 

 of life, totaling 732 persons. 



Between the great high, 30.53 inches, at Bermuda, which was 

 driving the tropical air, and the strong northern continental high, 

 which was pushing the polar air kept well chilled by the deep snow 

 cover of the region about and westward of Lake Superior, much as in 

 1937, the trough of low pressure moved but slowly for several days 

 (fig. 14). The fronts of 1913 were farther north than those of 1937, 

 and the belt of excessive rainfall in March 1913 (fig. 13) was about 

 100 miles to the north and somewhat to the east of that of 1937 (fig. 

 II); 18 and no excessive rains fell across the lower Mississippi in March 

 1913. The line dividing plus and minus temperature departures was 

 farther east in 1913 (85th meridian) than in 1937. 



COMPARISON WITH FLOODS OF 1922 AND 1882 



In March 1922 a well-developed high in the southwestern Atlantic, 

 averaging 0.14 inch above normal for the month at Bermuda, sent a 

 copius flow of tropical marine air into the United States. Encounter 

 with polar air masses took place over a broad area of the interior. 

 Precipitation was so widespread that, with the exception of the Ten- 

 nessee and Cumberland Rivers, the Mississippi and all its tributaries 

 were in flood at the same time. The rainfall contributing to this flood 

 as a whole, counting all the precipitation from January to April 

 inclusive over the entire 1,250,900 square miles of the Mississippi 

 drainage basin, averaged 10.58 inches, 33 percent of which came in 

 March and 36 percent in April. The run-off was 25 percent. Re- 

 gionally the March rainfall ranged from 13 inches in eastern Arkansas 

 to 11 in central Kentucky and up to 15 in Louisiana and 14 in southern 

 Mississippi. The rain fell mostly on March 10, 14 to 15, and 30 to 31, 

 when the tropical front passed through these regions ; while the supply 

 of tropical air was maintained by the Bermuda high, which was par- 

 ticularly strong in these three periods. Daily rainfalls were commonly 

 1.5 to 3 and nearly 4 inches. April's excessive rainfall was mostly 12 

 inches in southeastern Kansas to 9 inches in central Indiana. 19 



In January 1882 there was a southwest-northeast band of exces- 

 sive rainfall extraordinarily like that of January 1937 (fig. 11), with 

 rainfalls of 8 to 10 inches in eastern Texas up to over 15 inches in 

 eastern Tennessee; but this band lay about 100 miles south of that of 

 1937. 20 In February 1882, 8 to 10 inches of rain fell over Arkansas 

 and more than 8 inches over the lower Ohio Basin. The Cumberland 

 River at Nashville rose to 54 feet 7 inches, just topping the great flood 

 of 1847. The flood was due chiefly to the excessive rains, locally 3 



i 8 Cf. Swenson, loc. cit., fig. 24. 



» e Frankenfield, The spring floods of 1922, loc. cit. 



n Cf. Swenson, loc. cit., fig. 24. 



114728—39 23 



