permanent numbered grid covering the entire chart area. Column 2 lists 

 the wave information appearing on the latest synoptic wave chart, in the 

 present case, the 1230Z 11 January 195U chart. Columns 3> ht and $ contain 

 the predicted wind history, at 6-hour ly intervals during the forecast period. 

 Column 6 contains the predicted wind values as calculated from the prognostic 

 weather chart. The wind velocities are calculated on the basis of this geo- 

 strophic wind scale, with appropriate corrections made for isobaric curvature 

 and sea-air temperature differences. Column 6 also contains the predicted' 

 wave information which will be plotted on the prognostic wave chart. 



D. PRESENTED CHART SERIES 



The series of charts presented in this study are typical of the Atlantic 

 Ocean during winter, and, show wave heights normally associated with moderately 

 intense storms, from a meteorological standpoint, the synoptic situations 

 in this series are characterized by blocking action over the extreme eastern 

 portion of the Atlantic Ocean (not shown) which resulted in the storms ap- 

 pearing off the east coast of the United States being deflected toward the 

 north-northeast, and which also resulted in development of a strong pressure 

 gradient southward from Greenland. This condition prevailed until 11-12 

 January, after which time 'the blocking action relaxed, the Azores-Bermuda 

 high intensified, and the North Atlantic storms followed a more easterly 

 track. 



One important part of the analysis of a wave chart and the preparation 

 of a prognostic wave cfyart is the association of the predominant wave trains 

 with the synoptic weather systems generating themj therefore, a bried anal- 

 ysis of the presented series of charts will be made with this point in view. 

 The wave prognostic charts are based on the WBAN 30-hour prognostic charts, 

 verifying time 1230Z. 



Figure 1 is the wave chart for 1230Z, 7 January 195U and shows two pre- 

 dominant wave trains associated with the frontal system extending generally 

 southward from the vicinity of Nova Scotia. One train is associated with the 

 southerly flow ahead of the cold front and the other with the northwesterly 

 flow behind the front. This positioning of wave trains is typicsfl of all 

 such systems. Figure 2 is the 2li-hour prognostic wave chart based on figure 

 1. The prognostic wave chart shows the continuation of both wave trains with 

 an increase in wave heights corresponding to the expected increase in the 

 intensity of the frontal system. To a large extent, the wave heights ap- 

 pearing on the prognostic chart are calculated using the wave heights ap- 

 pearing on figure 1 as a starting point. Figure 1 is the verification for 

 figure 2. It shows the existence of both wave trains with prognosticated 

 wave heights agreeing reasonably well with those reported. The major error 

 is one of displacement of the axis of the wave trains; this is a common 

 error experienced in drawing the; prognostic Wave charts. 



Figure li is the 2h-hour prognostic wave chart, verifying time 1230Z, 9 

 January 19$)ij figure $ is the verifying chart for that time. It can be seen 

 that the prognosticated sea corxlitions ahead of the front a^ree satisfactorily 

 with the observed with respect to wave heights and direction and position- 



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