C-U. HURRIGAM RA.INFALL 



Heavy precipitation, often of torrential proportions, usually 

 accompanies a hurricane and in many cases will arrive several days 

 in advance, Pre-htirricane rainfall is produced when warm moist air, 

 circulating around the eastern or northern side of a hurricane, col- 

 lides witli the cold air along a far-distant, pre-existing front. The 

 September 193C storm, wherein the greatest part of the rainfall oc- 

 curred during the four day period before the hurricane crossed the 

 coast of Connecticut, is an example of pre-hurricane precipitation. 

 Approximately 90 percent of the rainfall at Providence was pre-hurri- 

 cane rainfall. An example of high rainfall immediately accompanying 

 a hurricane is the September ipJ^i; hurricane (see Table G-3),. Other 

 examples of hurricane rainfall wliich occurred coincident with the 

 hurricane itself are those of September 19^h (Sdna) and August 1955 

 (Diane) . 



TABLE C-3 



i-iupJiiOAirE r;j:iifall 

 naupjvgamsett BaI area 



Providence, ft. I, Fall itiver. Mass, Tavmton, Mass, Worcester jl-Iass, 



Ilax, !:ax, Ilax, Max, 



Hurricane 2U-Hr, Total 2l;-Hr, Total 2U-Hr« Total 2l;-Hr, Total 



(inches) (inches) (inches) (inches) (inches) (inches) (inches) (inches) 



The majority of the record floods in Uiis area have resulted from 

 hurricane rainfall. The heavy precipitation that generally accompanies 

 a hurricane has been the cause of numerous local flash floods, and has 

 also produced severe flooding on many of the large river basins when 

 following a long period of antecedent precipitation. A brief description 

 of recent hurricane river flooding in the Narragansett Bay area is given 

 in the following paragraphs and summarized in Table C-I;. 



G-k 



