195h) were lh2 miles per hour at Movmt Wasnington in New Hampshire 

 (170 miles north of Providence), 130 miles per hour at Block Island, 

 Rhode Island (1;^ miles southwest of Providence), 125 miles per hour 

 at the Blue Hill Observatory and 105 miles per ho\ir at the Theodore 

 Francis Green Airport in Warwick, Rhode Island, (7 #5 miles south of 

 the center of Providence), 



The diameter of the low-press\ire area in the center of hurri- 

 cane storms has measured as much as 30 miles but usually ranges from 

 10 to 15 miles. The lowest barometric presstire ever recorded in the 

 Western Hemisphere was 26,35 inches in the Florida Keys during the 

 hurricane of 1935. The minimum in New England was 28,OU inches re- 

 corded at Hartford, Connecticut, during the 1938 hurricane. The 

 minimum at Providence was 28,51 inches in the September 19lih hurri- 

 canej the lowest pressure recorded in New England during this storm 

 was 28,30 inches at Westerly, Rhode Island, In Hurricane Carol 

 (August 1951;), 28,20 inches was recorded at Storrs, Connecticut, 

 and 28,79 inches at Providence. Further data on wind velocities 

 and barometric pressures in past hurricanes are included in Appendix 

 •B. 



35. ASTRONOMICAL TIDE AND TIDAL FLOODING 



An important factor influencing the height of the hurricane 

 STirge is the stage of the normal tide at the time the surge arrives 

 at the coast. The September 1938 hurricane tide reached Narragansett 

 Bay approximately concurrent with the predicted high tide, whereas 

 the August I95ii hurricane tide occurred about two hours after the 

 predicted high tide. The September 1938 surge elevation at Providence 

 was 15.7 feet above mean sea level and the August 195U elevation was 

 Hi, 7 feet above mean sea level, but the difference between predicted 

 tide height and surge height was 13,3 feet in 195U and 12,6 feet in 

 1938, Thxas the 195U flood would have been about two feet higher and 

 about 0,7 foot above the 1938 flood level had it occurred at the tijne 

 of high tide. 



The September 19UU hurricane tide arrived at Providence about one 

 hour before the predicted low tide and therefore did not produce major 

 flooding. It reached an elevation of only 9.9 feet above mean sea 

 level at Providence although the rise above predicted tide elevation 

 was 11,6 feet. 



In determining future tidal flood levels, one factor to be con- 

 sidered is the rise in mean sea level that is taking place along the 

 New England coast. Continuing investigations being made by the U, S, 

 Coast and Geodetic Survey in regard to changes in sea level indicate 

 that mean sea level has risen at a rate of approximately 0,02 foot 



21 



