FLOODS — BROOKS AND THIESSEN 



331 



lated over the cold continent toward the low pressure over the warm 

 waters of the Gulf Stream and beyond. Occasionally, however, the 

 semipermanent high-pressure area of the subtropical Atlantic, which 

 is usually some distance east of North America, expands and builds 

 up westward into the Bermuda region. This happened in December 

 1936, starting, after a cold November, a most remarkably mild and 

 wet winter for the eastern part of the country. Bermuda pressures 

 were only moderately high in the first 3 weeks of December, but 

 from the 22d of that month until the 29th of January the morning 

 pressures did not fall below 30.20 inches. The mean for January was 

 30.32 inches, in place of the 29. 96-inch normal. Pressures must have 

 been higher farther east, for the wind at Bermuda was prevailingly 

 southeast to south. 



Why the high formed and stayed in the southwestern North Atlantic 

 is unknown. 



MEAN TEMPERATURE 

 DEPARTURE (F°1 



Jan. 19 -Jan 26, 1937 



Figure 1.— The departure of mean temperatures from the normal for the week ending 7:30 a. m., January 26, 

 1937. (From Weekly Weather and Crop Bull., January 26, 1937.) The shaded area shows excess tem- 

 perature (F.°); the unshaded area, deficiency; the dotted line, the southern limit of freezing weather. 



To favor high pressure at Bermuda, one should expect sea tempera- 

 tures to have been lower than usual there and higher than is common 

 farther east, 12 though it would hardly seem possible that even the 

 greatest sea temperature departures could account for the pressure 

 anomaly. The actual values of sea temperature, however, showed 

 departures similar to those of the air temperature, and, therefore, 

 were adverse rather than favorable to the westward extension and 

 intensification of the Azores-Bermuda high. The mean sea-surface 

 temperatures for December, January, and February about Bermuda 

 were 0.5, 3.4 and 0.5° F. above the average of the 20 years, 1912 to 



» Cf. Humphreys, W. J.: Why some winters are warm and others cold in the Eastern United States, 

 Monthly Weather Review, vol. 42, pp. 672-675, 1914. For a case the reverso of 1937 conditions see Brooks, 

 O. F., The "old-fashioned" winter of 1917-18, Geogr. Keview, vol. 5, pp. 405-414, 1918. 



