HURRICANES — GENTRY AND SIMPSON 321 



actual decrease in intensity. On September 23 the central pressure 

 was 996 mb. (29.41 inches) and maximum winds 90 m.p.h. 



During the early hours on the 24th, according to the Navy recon- 

 naissance plane, Janet never presented a good center definition and it 

 is not certain if the center was found. Late in the afternoon, one 

 very strong spiral weather band was found although the central pres- 

 sure remained about the same. At 8 : 30 E.S.T. on September 26, 

 Lieutenant Commander Windham with crew of eight and two news- 

 paper men reported at latitude 15°40' N. and longitude 78°02' W. 

 that they were about to begin penetration of the main core of the 

 storm. No further report was ever received from this plane. Janet 

 had become a very severe hurricane. The Navy reconnaissance plane 

 at 10: 40 E.S.T. on the 27th reported that the lowest pressure was 938 

 mb. (27.70 inches) and maximum winds in excess of 115 m.p.h. by a 

 large and uncalculable amount. Janet passed over Swan Island 

 during midday with winds estimated at 200 m.p.h. The hurricane 

 center reached Chetumal, Mexico, about 1 : 00 a.m. local time, Septem- 

 ber 28. It was still a very concentrated storm with winds reaching 

 hurricane force only about 2 hours before the arrival of the eye, 

 according to the description of Dunn, Davis, and Moore [7]. In 

 Chetumal the barometer reading of 27.00 inches was recorded in the 

 eye of the hurricane. In Corozal, British Honduras, only a few miles 

 from Chetumal, the barometer fell 2.24 inches in 2 hours and 10 

 minutes. The anemometer at the airport terminal building at 

 Chetumal registered 152 knots or 175 m.p.h. before it collapsed. The 

 wind later increased and the maximum is estimated in excess of 200 

 m.p.h. 



Hurricane Diane in 1955 is a good example of both rapid intensifi- 

 cation and also rapid loss of intensification. On August 11, the first 

 aircraft reconnaissance of Diane reported that the lowest pressure was 

 1,004 mb. (29.65 inches) and that the maximum winds were 45 m.p.h. 

 This was approximately the same maximum wind speed that had been 

 reported by ship observation on the previous day. During the night 

 the storm changed direction from a northwest course to a northeast 

 course and intensified rapidly. The reconnaissance on the 12th re- 

 ported that winds had increased to 125 m.p.h. and the central pressure 

 had deepened to 975 mb. (28.78 inches). After the 13th, the storm 

 began to fill and the intensity decreased. When the center passed 

 inland near Wilmington, N. C, early in the morning of the 17th, the 

 highest sustained wind reported was 50 m.p.h. at Hatteras, N. C, with 

 gusts up to 75 m.p.h. at Wilmington, N. C. 



What are some of the things that can cause a hurricane to change 

 intensity ? It is well established now that if cold or dry air is drawn 

 into the inner circulation of a hurricane, or if the hurricane goes over 



