The Caribbean climate warmed at the same 

 time that the Gulf coast cooled (fig. 36). This 

 condition was not unusual, for the mean 

 annual temperatures in Puerto Rico have been 

 "mirror images" of those in New Orleans 

 since 1900 (the year of first records on the 



is apparently in the transition zone between 

 the climates of the northern Gulf and northern 

 C aribbean. 



The cool ajonual temperatures have resulted 

 mainly from colder-thaui-usual winters. In 

 February 1958, for example, the month when 



SO 



25 



20 



IS 



MEAN ANNUAL TEMPERATURES 



SAN JUAN, PUERTO RICO 



-^_] 



NEW ORLEANS, LOUISIANA 



BLOCK ISLAND, RHODE ISLAND 



-J 1 1 1 1 1 1 L— 1 1 I 1_ 



' I ■ ' . ■ I ■ i ■ ■ I ^ ■ ■ ■ I ' ■ 



I ■ ■ ' ■ I ■ ■ ■ ■ I 



1690 



■ ' ' ■ ' ' L. 



1900 



1920 



1950 



Figure 36. --Annual mean temperatures at representative Atlantic and Pacific stations. Gross correlations north of 



Puerto Rico are noteworthy. 



island). The climatic regimes of the Gulf 

 and Caribbesui are clearly different. Conse- 

 quently, the details of the climates must be 

 learned, for the Gulf waters come under the 

 influence of the atmosphere in both the Carib- 

 bean and the Gulf regions. 



The cool air extended to Key West in 1958 

 and 1960, but, in other years since 1958, the 

 nnean amnual temperature there has been 

 warmer than normal. In Tampa, 483 km. 

 north of Key West, the annual temperatures 

 followed those of Key West from 1958 through 

 1961. But Tampa has continued to have cold 

 years through 1965 (fig. 37). Thus, Key West 



the 6-year decline began, the meam tempera- 

 tures along the Gulf coast were 10° C. below 

 normal (Mobile; fig. 38). The cold air was 

 introduced over the Gulf of Mexico when an 

 unusually strong and persistent anticyclone 

 was situated over the western United States. 

 The prevailing winds, which in the warm 

 February of 1956 blew from the south and 

 east across balmy waters (fig. 39), in February 

 1958 were strong and from the north (fig. 40). 

 The cooler air has corresponded withcooler 

 waters in the western Atlantic Ocean since 

 1960 and, thus, cooler waters in the Gulf. 

 (This problem is under investigation by marine 



ANNUAL AVERAGE TEMPERATURE ('C 



BROWNSVILLE 

 TAMPA 



GALVESTON 

 MOBILE 



1940 



Figure 37.~The annual average air temperatures for major stations near the Gulf of Mexico, 1900-65. Note the 

 "cold year" throughout the Gulf region in 1958; the continuing sequence of "cold years" in the northern Gulf, 

 as at Galveston; and the "warming tendency" at Key West and Brownsville. 



34 



