3RoebImg Jfunb 



WASHINGTON, D. C, PRECIPITATION OF 

 1954 AND 1955 



By C. G. abbot 

 Research Associate, Smithsonian Institution 



This is the eleventh year of these papers regarding precipitation on 

 individual days at Washington, D.C.^ Last year ^ it was stated that 

 the precipitation of 1952 and 1953 departed greatly from the pattern 

 of previous years. This was shown graphically by a figure. But it 

 was pointed out that the great unexpected peak on the eleventh day of 

 the cycle of 27.0074 days, used in these publications, was much lower 

 in 1953 than in 1952. It has disappeared entirely in 1954, as is shown 

 here in figure i. A moderate unexpected peak, however, appears on 

 the ninth day of the cycle in 1954. This peak is principally caused by 

 the rain of 1.87 inches which fell on May 3, 1954- 



In figure i the line AA shows average of precipitation in 1954, and 

 the line BB shows the average in the original tabulation of 1924 to 

 1941. One notes that the days i, 2, 3, 5, 12, 13, 16, 18, 22, 26, and 

 27 — eleven out of the original thirteen, which had greater than 

 average precipitation in the tabulations for the years 1924 to 1941 — 

 had greater than average precipitation in 1954- 



The year 1954 was a dry year in Washington, but the drought was 

 by no means so severe as that in the southern and southwestern 

 United States, though the precipitation in February, July, and Sep- 

 tember of 1954 was far below normal. It now (January 29) appears 

 likely that the month of January 1955, will be drier than any of those 

 months. 



Notwithstanding the peculiarities of Washington precipitation in 

 1952, 1953, and 1954, just referred to, the prediction published last 

 year, based on a cycle of 27.0074 days, was successful in 1954. The 

 average daily precipitation of the 177 selected preferred days was 1.31 

 times the average daily precipitation of all other days of 1954. The 

 average daily precipitation on preferred days for 18 years prior to 



1 The first, Smithsonian Misc. Coll., vol. 104, No. 3, 1944. 



2 Ibid., vol. 122, No. 13, 1954. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 128, NO. 2 



