Pacific hurricane

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Cumulative average number of tropical cyclones in the eastern north Pacific
Cumulative average number of tropical cyclones in the eastern north Pacific

A Pacific hurricane is a tropical cyclone that develops in the northeastern part of the Pacific Ocean. For organizational purposes, the Pacific Ocean is divided into three regions: the eastern, (North America to 140°W), central (140°W to the International Date Line), and western (west of the Date Line). A Pacific hurricane, then, is a tropical cyclone in the northern Pacific Ocean east of the Date Line. Identical phenomena in the western north Pacific are called typhoons. This separation between the two basins is convenient, however, as tropical cyclones rarely form in the central north Pacific and few ever cross the dateline.

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[edit] Eastern North Pacific

Hurricane season runs between May 15 and November 30 each year.[1] These date encompass the vast majority of tropical cyclone activity in this region.

The Regional Specialized Meteorological Center for this basin is the United States' National Hurricane Center. Previous forecasters are the Eastern Pacific Hurricane Center and the Joint Hurricane Warning Center. The RSMC monitors the eastern Pacific and issues reports, watches and warnings about tropical weather systems and cyclones as defined by the World Meteorological Organization.

This area is, on average, the second-most active basin in the world. There are an average of 16 to 17 tropical cyclones annually, with 9 becoming hurricanes, and 4 becoming major hurricanes.[2] Tropical cyclones in this region frequently affect mainland Mexico and the Revillagigedo Islands. Less often, a system will affect the Continental United States or Central America. Northbound hurricanes typically reduce to tropical storms or dissipate before reaching United States: there's only one recorded case of a Pacific system reaching California as a hurricane in almost 200 years of observations - the 1858 San Diego Hurricane.[3]

[edit] Central Pacific

Hurricane season runs from June 1 to November 30, with a strong peak in August and September. However, tropical cyclones have formed outside those dates.[1] Should a tropical cyclone enter the central north Pacific from the western north Pacific, where they occur year-round, or from the eastern north Pacific, where the season starts in May, outside of those dates, it is not known if such a system will be considered out of season or not.

The Central Pacific Hurricane Center is the RSMC for this basin and monitors the storms that develop or move into the defined area of responsibility. A previous forecaster was the Joint Hurricane Warning Center.

Central Pacific hurricanes are rare and on average 3 or 4 storms form or move in this area. Most often, storms here are weak and are often declining upon entry. The only land tropical cyclones can impact here is Hawaii or Johnston Atoll. Due to small size, direct hits and landfalls are rare.

[edit] Steering factors

See also: Tropical cyclone track forecasting and Subtropical ridge

Hurricanes in the Eastern Pacific tend to move westward out to sea, harming no land. However, hurricanes can recurve to the north or northeast, hitting Central America or Mexico early and late in the hurricane season.

[edit] See also

[edit] References

  1. ^ a b Tropical Cyclone Climatology. FAQ. Central Pacific Hurricane Center. Retrieved on 2007-12-31.
  2. ^ National Hurricane Center. Tropical Cyclone Climatology. Retrieved on 2008-04-19.
  3. ^ Michael Chenoweth and Chris Landsea. The San Diego Hurricane of 2 October 1858. Retrieved on 2008-04-19.