28 

 Cold Front Passages 



Two primary and three secondary meteorological patterns 

 result in bringing onshore wind waves to Santa Monica Bay„ 

 These waves, characterized by their choppiness and short period, 

 are always accompanied by strong winds, and since they are 

 generated within the general area, the sheltering influence of 

 the points, headlands, and islands is not so well marked . 

 Because the height and period of the wind waves is a function 

 of the wind fetch as well as the wind velocity and duration, 

 a variation in size and period of the wind waves with the wind 

 direction is to be expected. 



Whenever the Pacific High has weakened or moved far enough 

 south, and northwesterly flow prevails over the eastern margin 

 of the Pacific Ocean, cold fronts originating in the Southern 

 Gulf of Alaska may move to southern California., During the 

 winter season this may occur several times a month bringing 

 rain and moderate winds, in the main, first from the west and 

 then the northwest. At times, before the frontal crossing, 

 southwest winds may blow for a short period, generally less 

 than a day, causing a flat sea. 



As the fronts approach California, the winds and fronts 

 move in about the same direction with the latter often 

 traveling at approximately the same speed as the group velocity 

 of the waves. Only rarely do the winds and waves follow a 

 bearing of less than 270°. This means that fairly high wind 

 waves of moderate period will enter Santa Monica Bay. Since 

 most of the wind waves will be traveling in a southeasterly 

 direction, they will be greatly modified along the Malibu 

 shore. 



