NO. 3 



SIXTY-YEAR WEATHER FORECASTS — ^ABBOT 



We must wait three years to compare these predictions fully with 

 the events. As a caution therein, it will be recalled that I deal entirely 

 with 5-month running means. 



One notes with pleasure that there is promise of approaching relief 

 from the prevailing distressing drought in 1957. Its approach and 

 advance from 1952 are well shown by St. Louis prediction. 



l^^- 



FiG. 6. — Predicted precipitation, Peoria (upper) and St. Louis (lower), 1952- 

 1957. from mean forms of 22 periodicities over the epoch 1854-1939. End of 

 prediction 18 years after 1939 and 60 years after middle of base, 1897. Dotted 

 curves, prediction; full curves, event. Horizontal lines represent normal pre- 

 cipitation. Drought indicated ending 1957. 



2. DETAILED METHOD OF FORECASTING 



The method rests on the discovery of a family of regular periodici- 

 ties in weather and other phenomena, all, to within i percent, exact 

 submultiples of 22| years. To express the matter more precisely, the 

 master period is 22| X 365-|: days. Not until recently was I aware that 

 the period I found several years ago in New York and Washington 

 temperatures, 6.6485 days,*^ is itself a member of this family. For 

 221x365:!: days is 8309.44 days; which divided by 1250=6.64754 

 days, a value less than i percent different from the other. My friend 

 Dr. F. P. Marshall found a period of 212 days, and 15 exact submul- 

 tiples of it, in a record of 3 years of daily basal pulse rates. Seven 

 months, a period used in all of my syntheses, is %2 x 365:^ days = 213.3 



^Smithsonian Misc. Coll., vol. iii. No. 17, 1950. 



