165 W. during July and August and to 36 N. 

 on 141°W. during August (U.S.N.H.O. 1401). 

 In the northern part of the cruise area there 

 is normally little or no wind because of the 

 great extent of the center of the high. 



During the winter months, October 

 to March, when the high is weak the Aleutian 

 Low is the predominant climatic feature of the 

 North Pacific. In this period the mean northern 

 limit of the northeast trade wind belt is much 

 farther south, and the trade winds have lower 

 velocities and greater variation in direction 

 than during the summer months. Its most 

 southern position is between 23 N. and 24 N. 

 latitude during November, February, and March 

 on 165 W. longitude, and at the same latitudes 

 during November on 141 W. longitude (U.S.N. 

 H. O. 1401). In the northern part of the area 

 the prevailing winds are westerly because of 

 cyclonic circulation around the Aleutian Low 

 and anticyclonic circulation around the high . 

 The mean position of the southern boundary of 

 the westerlies is farthest south during January 

 and February, when it is at approximately 

 30°N., from 165°W. to 155°W. , and extends 

 northeastwardly to approximately 34 N. on 

 141 W. longitude. The limits of westerlies 

 are not as meaningful as those of the north- 

 east trades because of the great variability in 

 the paths and intensities of the lows that sweep 

 across the North Pacific. 



normal charts. A composite of the major fea- 

 tures of these charts is shown in figures 2 

 through 4. 



Stations 1 through 28 were occupied 

 January 12 to 31, during which time the mean 

 surface pressure was very differ ent from normal. 

 The semi-permanent high, as indicated by the 

 cell of greater than 1, 020-mb. pressure (fig, 2), 

 was much smaller than normal and centered 

 slightly east of its normal position. The Aleutian 

 Low was much weaker and more diffuse than 

 normal; it actually consisted of four small cells, 

 none of which attained the usual depth of less 

 than 1,000 mb. These conditions are indicative 

 of a period of relatively weak zonal westerlies 

 whose limits extend farther south than normal. 

 This is shown in figure 2 by the restricted 

 westerly extent of the approximate limits of the 

 westerlies and trades and the southerly shift of 

 the limits relative to the mean position. The 

 weakness of the zonal circulation is also shown 

 by the differences in the paths of the lows which 

 had their origin in the vicinity of Japan and the 

 large number of lows that originated in mid- 

 ocean. The effects of the southerly shift in the 

 westerlies and the large number of lows that 

 originated in mid-ocean are shown by the pre- 

 dominance of westerly winds (fig. 5) and the 

 number of fronts (fig. 6) that were encountered 

 alone and between the transects on 165 W. and 

 160 W. 



During the winter months another 

 source of storms that affect the area covered 

 by Hugh M. Smith cruise 25 is the subtropical 

 cyclones which frequently develop near the 

 Hawaiian Islands south of the main stream of 

 the polar westerlies. These storms, locally 

 known as Kona storms (Simpson 1952), form 

 as waves in quasi-stationary cold fronts and, 

 because of their proximity to the Eastern North 

 Pacific High, usually develop slowly or die 

 without becoming very intense. However, when 

 they form as a new or secondary front associ- 

 ated with a frontal system farther north, they 

 are vigorous and cause high winds and heavy 

 rainfall. 



The meteorological conditions 

 during any given period deviate considerably 

 from the average conditions described above. 

 The manner and amount of the deviation and 

 its effect on the actual conditions encountered 

 is of importance when considering oceanogra- 

 phic data. Therefore, the mean monthly sea 

 level pressure charts (furnished by the U.S.W. 

 B. ) and the daily weather charts (prepared by 

 the U.S.W.B. , Honolulu, T. H. ) for January 

 through March 1954 were compared to the 



The general features of the mean sea 

 level pressure chart for February, the period 

 during which stations 29 through 63 were occu- 

 pied, were similar to the normal chart in most 

 respects (fig. 3). The Aleutian Low was about 

 normal in intensity and centered only slightly 

 southeast of its usual position, indicating that the 

 storms that originated along the Asiatic coast 

 were following their usual pattern. The eastern 

 North Pacific High was displaced slightly north- 

 east of its mean position and was slightly less 

 intense than usual. The latter condition resulted 

 in a 3- to 4-degree southerly displacement of the 

 northern limit of the northeast trade wind belt. 

 The most marked departure from normal was 

 the trough which occurred in the area west of the 

 Hawaiian Islands; this trough was the source of 

 the storms which produced the high winds and 

 fronts encountered by the Smith during February 

 (figs. 5 and 6). 



Of the three months covered by the 

 cruise period, the mean surface pressure chart 

 for March 1954 (stations 64 through 89 were oc- 

 cupied between March 1 and 16) departed most 

 radically from normal (fig. 4). The center of the 

 Aleutian Low was about normal in position and 



