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ABSTRACT
The 1998 eastern North Pacific hurricane season is reviewed. There were 15 tropical cyclones, consisting of nine hurricanes, four tropical storms, and two tropical depressions. During 1998, two tropical cyclones made landfall; Hurricane Isis made two landfalls in Mexico while Tropical Depression Javier dissipated near Cabo Corrientes, Mexico.
1. Introduction
The most prominent characteristic of the 1998 eastern North Pacific hurricane season was the below-normal number of landfalling tropical cyclones. On average, three or four tropical cyclones strike the coast of Mexico each year but only two tropical cyclones made landfall during 1998. Hurricane Isis made two landfalls in Mexico, it passed over southern Baja California and then finally passed onshore near Los Mochis, where it claimed 14 lives. Weakening Tropical Depression Javier dissipated over land near Cabo Corrientes, Mexico, without consequence.
The 1998 eastern North Pacific hurricane season also featured United States Air Force Reserve (USAFR) reconnaissance flights into Hurricanes Lester and Madeline, which threatened the coast of Mexico. These flights were coordinated through the government of Mexico and served to test flight clearance procedures in Mexican airspace.
The average numbers of tropical storms and hurricanes per year in the eastern North Pacific basin are 16 and 9, respectively. While the number of named storms in 1998 was below average (13), the number of hurricanes was equal to the long-term average. Of the nine, six attained category 3 or higher status on the SaffirSimpson hurricane scale (SSHS) (Simpson 1974) with estimated 1-min sustained winds ? 100 kt. A summary of 1998 tropical cyclone statistics appears in Table 1.
The season got off to a late start with the development of the first tropical cyclone, Agatha, on 11 June. Historically, the median day for formation of the first eastern North Pacific tropical cyclone is 31 May.
Most of the tropical storms and hurricanes remained away from land on climatologically favored tracks toward the west-northwest. Prevailing steering resulted from a persistent 50-mb anticyclone located over the western United States. This feature persisted throughout most of the summer. A few tropical cyclones threatened Baja California during short periods when the strong anticyclone weakened. In most of these cases, however, the anticyclone reestablished itself and steered the storms to the west-northwest before they reached Baja...