FLOODS BROOKS AND THIESSEN 



337 



em plateau region, where a blanket of snow maintained the original 

 polar frigidity of the air. As thrust after thrust of polar air pushed 

 southward in floods deep enough to overtop the usually protecting 

 mountain wall of southern California — as indeed the floods of waters 

 had overtopped the protecting walls along the great rivers in the 

 East — this famous subtropical corner of the United States experienced 

 a month of frequent freezes, ice, and occasional snow and was often 

 colder than southern New England. The mean temperature of 

 January at Los Angeles was 1.3° F. lower than the coldest on record. 

 Two pronounced periods of cold, January 7-11 and 19-28, the latter 

 coinciding with the rainiest period in the Ohio Valley, destroyed about 

 40 percent of the orange crop, despite frantic efforts to heat the or- 

 chards. 14 Farther north, real wintry weather prevailed over the 



Figure 12.— Rainfall, Mar. 23 to 27, 1913 

 (after F. J. Walz, Monthly Weather Rev., 

 March 1913; map opposite p. 368). 



Figure 13. — Total precipitation in the eastern 

 United States, March 1913. 



coastal belt as well as to the east. At the end of January Portland 

 was buried in its heaviest snowstorm of record. 



Is western cold the normal accompaniment of eastern floods? In 

 table 1 are shown temperature departures of months when flooding 

 rains were producing great floods in the east. Subnormal tempera- 

 tures in San Diego have been coincident with the chief rainy months 

 of all other general floods of winter or early spring in the Ohio and 

 lower Mississippi valleys since 1882: the years 1883, 1897, 1903, 1907, 

 1912, 1916, 1920, and 1926 (December). Obviously, widespread and 

 great flooding rains in the Ohio and lower Mississippi valleys are 

 attended by cold weather in southern California owing to a natural 

 opposition between the great interlatitude currents of air. 



" Cf. Ackerman, E. A., The 1937 California freeze. Bull. Amer. Meteor. Soc, vol. 18, pp. 240-241, 1937 

 Young, F. D., The 1937 freeze in California. Monthly Weather Rev., vol. 66, pp. 311-324, 13 figs., 1938 



