In the cper. ocean th'^ rise due to the stor.:; siirge neldon 

 exceeds 3 -feet, but it increases considera'bly on the continental 

 shelf and alon^ the coastline where it builds up in height, in 

 •".luch ti^e sar.ie way that a ground si-:ell builds up in shoal vrater. 

 An additional rise in level occurs due to th.e effect of hurri- 

 cane i/inds "^P-ovrin^ ovrr clioaling; coastal waters and sliallow hays 

 and inlets, depending on the fetch, tlie depth of the water, and 

 the wind intensity and duration. The rises in level from the 

 co.ibin^^tion of of . "shore surge and local v.dnd effects may range 

 ircr.1 6 to c feet above normal hic;h tide on the coast, and to 12 

 or lii feet above normal high tide in bays and inlets* 



DcSIGN HURRir.4NE TIDAL FLOCD 



33. AMA.LY3I3 OF Til? ITUT-'liaA.NE oLOGE 



As a hurricane progresses over the open water of the ocean, 

 a tidal svrge is built up, not. only by the force of the wind and 

 the fon-rard movement of the storra v;ind field, but also by differ- 

 ences in at/.iospheric pressure accompanying the storm. TMs siorge 

 is further increased as the ctonu approaches land over a gradually 

 shoaling ocean bed and is influenced considerably by tlie contours 

 of the ccastline. An additional rise results when the tidal surge 

 invades a bay or estuary and h\arricanc winds drive waters to higher 

 levels in the shallow waters. Tidal surges are greater and the 

 tidal flooding more severe in coastal corimunities whicli lie to 

 the right of the storm path, due to the counter-clocl<i-7ise spiraling 

 of the liurricane winds and the forward movement of the storm. The 

 actual height reached by a hurricane tidal surge and the consequent 

 damr.gcs incurred depend on many complicated factors, 



3U. WIND FIELD Aim PiL^.GIETIlIG PRESSURE 



The maxiiaum gust of vjind recorded in any hurricane in Hew 

 England is 186 miles per hottr; a sustained 5-:^nute velocity of 

 121 r,u.les per hour vras recorded in the Septenber 1932 hiirricane 

 at the Blue IUll Observatory, Hilton, I-Iassachusetts, about 30 

 miles north, of Providence, At Providence, the maximum recorded 

 l-:pdnute sustained wind velocity vjas 9? miles per hour, with a 

 5-"U.nute sustained blow of u7 miles per hour and m?jdLmum estimated 

 gust of 125 miles per hour, in 193G. During the hurricane of 

 September 19Ui;, the maximum gust in New England iras lOU miles 

 -per hour at Cliatham, liassachusetts, about k^ miles east of llev: 

 Bedford, Pealc gusts measured during Hurricane Carol (August 



20 



