1950-1969 Pacific hurricane seasons

A Pacific hurricane is a mature tropical cyclone that develops within the eastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regions: the eastern (North America to 140°W), central (140°W to 180°), and western (180° to 100°E), while the southern Pacific is divided into 2 sections, the Australian region (90E to 160°E), the southern Pacific basin between (160°E to 120°W). Identical phenomena in the western north Pacific are called typhoons. This separation between the two basins has a practical convenience, however, as tropical cyclones rarely form in the central north Pacific and few cross the dateline.

Documentation of Pacific hurricanes dates to the Spanish colonization of Mexico, when the military and missions wrote about "tempestades". In 1730, such accounts indicated an understanding of the storms. After observing the rotating nature of tropical cyclones, meteorologist William Charles Redfield expanded his study to include storms in the eastern North Pacific Ocean in the middle of the 19th century. Between June and October 1850, Redfield observed five tropical cyclones along "the southwestern coast of North America", along with one in each of the three subsequent years. In 1895, Cleveland Abbe reported the presence of many storms between 5° to 15°–N in the eastern Pacific, although many such storms dissipated before affecting the Mexican coast. Two years later, the German Hydrography Office Deutsche Seewarte documented 45 storms from 1832 to 1892 off the west coast of Mexico.

Despite the documentation of storms in the region, the official position of the United States Weather Bureau denied the existence of such storms. In 1910, the agency reported on global tropical cyclones, noting that "the occurrence of tropical storms is confined to the summer and autumn months of the respective hemispheres and to the western parts of the several oceans." In 1913, the Weather Bureau reinforced their position by excluding Pacific storms among five tropical cyclone basins; however, the agency acknowledged the existence of "certain cyclones that have been traced for a relatively short distance along a northwest course... west of Central America."

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