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ABSTRACT
Overall activity during the 2011 eastern North Pacific hurricane season was near average. Of the 11 tropical storms that formed, 10 became hurricanes and 6 reached major hurricane strength (category 3 or stronger on the Saffir-Simpson hurricane wind scale). For comparison, the 1981-2010 averages are about 15 tropical storms, 8 hurricanes, and 4 major hurricanes. Interestingly, although the number of named storms was below average, the numbers of hurricanes and major hurricanes were above average. The 2011 season had the most hurricanes since 2006 and the most major hurricanes since 1998. Two hurricanes affected the southwestern coast of Mexico (Beatriz as a category 1 hurricane and Jova as a category 2 hurricane), and the season's tropical cyclones caused about 49 deaths. On average, the National Hurricane Center track forecasts in the eastern North Pacific for 2011 were very skillful.
1. Introduction
Although the 2011 eastern North Pacific hurricane season was more active than most of the hurricane seasons since 1995, overall activity was near the long-term average. Of the 11 tropical storms that formed in 2011, 10 became hurricanes and 6 reached major hurricane strength [maximum 1-min 10-m winds greater than 96 kt (1 kt 5 0.5144 m s21)-corresponding to category 3 or greater on the Saffir-Simpson hurricane wind scale; Saffir (1973); Simpson (1974); Schott et al. (2010)]. In addition, there were two tropical depressions that did not strengthen into tropical storms. Although the number of named storms was below average, the numbers of hurricanes and major hurricanes were above average. In fact, 2011 had themost hurricanes since 2006 and the most major hurricanes since 1998. In terms of the accumulated cyclone energy (ACE) index (Bell et al. 2000), which accounts for the intensity and duration of the season's storms, the value for the 2011 season was 119.6 3 104 kt2, or about 113% of the long-term (1981- 2010) median value of 106 3 104 kt2. Like most years in the basin, the bulk of the cyclone activity remained offshore of the coasts of Mexico and Central America However, Beatriz affected the southwestern coast of Mexico as a category 1 hurricane in June (Fig. 1), and Jova made landfall in the same region in mid-October as a category 2 hurricane (Fig. 2). A...