240 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



Our greatest hour's pressure fall was 0.5 inch [17 millibars], and the greatest 

 hour's rise was 0.57 inch [19 millibars]. During one 10-minute interval the 

 pressure rose 0.17 inch [6 millibars]. The steepest gradient I could measure 

 was that extending from Elizabeth City, N. C, to the [margin of the eye at the] 

 storm center at 11 : 35 a. m., a pressure difference of 0.90 inch [30 millibars] in 

 38 miles, which on a map drawn for 3-millibar interval would place the isobars 

 less than 4 miles apart. [Apparently within the 28.90-inch (979-millibar) iso- 

 bar the pressure gradient decreased little if any outward from the center. Con- 

 sequently, the maximum wind occurred at about the time of passage of the 

 979-millibar isobar, which was some time after the passage of the center for the 

 stations practically on the track (Hatteras, 1 hour 40 minutes; Wanchese, 2 

 hours), but virtually at the time the center was nearest for stations at or beyond 

 the 60-mile distance of the 979-millibar isobar from the center (Elizabeth City, 

 N. C, and Norfolk, Va., 5 minutes difference; Cape Henry, 12 minutes).] 



THE STORM NORTH OF HATTERAS 



The transformation from a slowly moving completely tropical 

 storm to a rapidly moving cyclone with middle-latitude features was 

 now in progress. Cooler, drier air from the land curving around the 

 rear tended to make the pressure rise more rapidly behind, while the 

 warm sea air flowing in ahead made it fall more rapidly in front. 

 Cool air on the northwest also had increased the northwestward pres- 

 sure slope aloft, thereby accelerating the general current that later 

 carried the storm ; and energy from the tendency of the colder, denser 

 air to underrun the warmer, lighter air mass offset in part the de- 

 creasing receipt of tropical vapor as the storm entered cooler latitudes. 



The combined effect caused a still more rapid increase in the speed 

 and a change of direction of the cyclone, at first toward the north- 

 northeast, parallel to the coast to northern New Jersey, then toward 

 the northeast, across Long Island east of Suffolk Airport. The cen- 

 ter traveled the 400 miles from Hatteras to Long Island in 11 hours. 

 The barometer at Suffolk fell to 28.42 inches, and gusts reached 100 

 miles an hour. 



At Bridgehamton, about 18 miles east of Suffolk Airport, the center 

 also passed on the east. Ernest S. Clowes writes : 5 



There was a distinct "calm center" from about 10 to 10 :30 p. m., E. W. T. The 

 lowest barometer occurred soon after 10, and for about half an hour the wind was, 

 I'd say, around 10 to 15 m. p. h., with the sky mostly clear and starlit though 

 with occasional smart showers, very brief. The wind was variable but mostly 

 NE. to N. At 10 : 45 I estimated the wind as 65 m. p. h. from NW. The rain- 

 fall for the storm, 5 to 11 p. m., was 2.78 in. 



The center continued moving northeastward, at 35 to 40 miles an 

 hour, passing between Fishers Island and Block Island, across Rhode 

 Island (between Westerly and Point Judith, East Providence), south- 

 eastern Massachusetts (East Wareham, Taunton, Brockton, South 



8 Personal communication. 



