13. Two additional storms from outside the 1956-1975 period were in- 

 cluded in the storm ensemble: 29 November 1945 and 6 February 1978. All the 

 necessary data were obtainable for these storms which caused the first and 

 second highest surges recorded at Boston. Furthermore, the February 1978 

 event caused the highest still-water level (10.3 ft NGVD) on record in 

 Boston. Adding these two storms helped ensure the top end of the storm en- 

 semble was representative of what could occur at Boston. Therefore, a total 

 of 28 storms was chosen to represent the surge time-histories which are 

 possible at Boston. Table 1 contains a list of these storms and their maxi- 

 mum surges. The maximum surges listed in Table 1 might differ slightly from 

 maximum surges derived elsewhere. There are two reasons for these small 

 discrepancies. First, great care was taken to use a set of tidal prediction 

 constituents which best fits the tidal signal at Boston. With the large tidal 

 range at Boston, slight errors in phase could cause significant errors in the 

 calculated surge. Five separate sets of constituents received from NOS were 

 tested, and the set of constituents with the best fit was used for these 

 calculations. Second, often the maximum surge in historical storms occurs at 

 low water because of the increase in surge with decreasing water level given 

 constant wind speed and direction. Since the surges needed to be independent 

 of their historic tide, the surge time-histories were edited by eye to remove 

 12-hour oscillations caused by this shallow-water effect. 



Table 1 

 Historical Storms Chosen to Represent Possible Surges at Boston 



Storm 





Maximum Surge 



No. 



Date 



ft 



1 



11-30-45 



4.8 



2 



1-9-56 



3.3 



3 



3-16-56 



3.3 



4 



4-8-56 



2.6 



5 



1-8-58 



2.9 



6 



1-15-58 



2.7 



7 



2-16-58 



3.6 



8 



3-15-58 



2.8 



9 



3-21-58 



3.2 



10 



4-2-58 



2.7 



11 



12-29-59 



2.6 



12 



2-19-60 



2.5 



13 



3-4-60 



3.7 



14 



1-20-61 



3.4 



Storm 

 No. 



15 

 16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 



Date 



4-13-61 



3-7-62 



12-6-62 



2-19-64 



1-23-66 



1-30-66 



12-25-66 



2-9-69 



12-27-69 



2-4-72 



2-19-72 



11-9-72 



12-16-72 



2-6-78 



Maximum Surge 

 ft 



4.4 

 2.5 

 2.7 

 2.7 

 3.1 

 3.6 

 2.9 

 3.4 

 3.2 

 2.9 

 4.0 

 2.8 

 3.2 

 4.7 



13 



