STATE AGRICULTURAL SOCIETY. 407 



ORIGINAL METEOROLOGICAL RESEARCHES. 



Through the kindness of Prof. H. W. Harkness, President of the Cali- 

 fornia Academy of Sciences, San Francisco, Ave are enabled to publish the 

 following article, u Weather Types on the Pacific Coast," (with plates), by 

 Lieutenant W. A. Glassford, U. S. A., Assistant Signal Officer in charge of 

 the branch office at San Francisco during 1886. These " Weather Types" 

 are original, interesting, and instructive. The Lieutenant deserves great 

 credit for his meteorological researches on the peculiarities of the weather 

 types on the Pacific Coast. The article deserves close and careful study 

 by the many voluntary meteorological observers and others who take great 

 interest in the science of the climate of the Pacific Coast. 



WEATHER TYPES OX THE PACIFIC COAST. 



By W. A. Glassford, Second Lieutenant Signal Corps, U. S. A., Assistant. 



A short study of the charted weather reports of the Pacific Coast, reveals 

 certain types lasting for a considerable period which admit of classifica- 

 tion. East of the Rocky Mountains, however, no such characteristics are 

 present; the storms or cyclonic areas, as well as the anti-cyclonic or areas 

 of high pressure generally originate in the Gulf of Mexico, the Rocky 

 Mountain slopes, or in British America, and move in succession over a 

 curved path, almost invariably to the eastward, at a uniform rate, and with 

 uniform characteristics. They disappear as regularly near Nova Scotia. 

 It is very seldom, if ever, that perfect paths of low pressure areas are 

 traced from the Pacific Coast across the mountain plateaus and ranges, 

 although some few cases have been charted on the storm track maps; but 

 even these are not so uniform as in the East, for they frequently tarry for 

 quite a period, clinging to some valley or plateau. On this coast a notice- 

 able feature is the difference in the storm frequency between the northern 

 and southern boundary lines of the United States. Areas of low pressure 

 of any intensity are of infrequent occurrence in Southern California, but 

 going north become more frequent as Vancouver Island is approached. 

 From a search of the weather reviews for three years, it is found that areas 

 of low pressure entering the Pacific Coast States from the ocean during 

 that period number 90; those north of the forty-fifth parallel are 54; between 

 45° and 40°, 25; between 40° and 35°, 10; below the thirty-fifth parallel, 1. 

 Another peculiarity of the areas of high and low pressure here is their 

 arrangement in recurring and symmetrical types; recurring, because there 

 is a tendency to assume the same barometric condition on successive days; 

 symmetrical because the recurrence as denoted by the barometer takes 

 about the same area, shape, and intensity. 



Except the November (1885), and the greater storm of January last ( 1886) , 

 and, in fact, the centers of these were the whole time at sea, there has been 

 no distinct cyclonic area, such as appear in the Eastern States, central 

 over California during the past season (1885-86). Those who examine the 

 Signal Service synoptic charts with its reports may have observed " High " 

 and "Low" designated, but these are often such only by contrast; the 

 areas where the group of barometric readings reduced to sea level are the 

 greatest or the least that appear on the map, being so named. 



