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(Manuscript received 12 June 1998, in final form 5 October 1998)
ABSTRACT
The 1997 Atlantic hurricane season is summarized and the year's tropical storms, hurricanes, and one subtropical storm are described. The tropical cyclones were relatively few in number, short lived, and weak compared to long-term climatology. Most systems originated outside the deep Tropics. Hurricane Danny was the only system to make landfall. It produced rainfall totals to near 1 m in southern Alabama and is blamed for five deaths. Hurricane Erika was responsible for the season's two other fatalities, in the coastal waters of Puerto Rico.
1. Introduction
A sharp drop in tropical cyclone activity occurred in the Atlantic hurricane basin from 1995-96 to 1997 (Table 1). Only seven tropical storms formed in 1997, and just three of those reached hurricane strength (Table 2). This also represents a considerable reduction from the long-term averages of ten tropical storms and six hurricanes. The months of August and September were particularly quiet. On average, about six tropical storms develop during that two-month period (Neumann et al. 1993). There was just one in 1997, an occurrence last noted in 1929. Also, for the first time since 1961, no tropical cyclones formed in August.
Hurricane Danny, which formed over the Gulf of Mexico, was the only system to make landfall. Hurricane Erika brushed the northeastern Lesser Antilles and was the only cyclone to become a "major" hurricane, that is, to have winds of at least 96 kt (1 kt = 0.5144 m s ') over 1 min [category three or higher on the Saffir-Simpson hurricane scale; Simpson (1974)].
All but one tropical cyclone (Erika) formed in the western part of the hurricane basin at relatively high latitudes, 22 deg -32 deg N (Fig. 1). In contrast, 11 of the 13 tropical cyclones in 1996 formed south of 22 deg N. Most of 1997 systems originated in association with low-level frontal boundaries or upper-level disturbances. In general, these systems were rather short lived and weak, encountering strong vertical wind shear and rather cool waters after just a few days. Tropical waves contributed directly to the formation of only two named systems.
This is one of the smallest contributions (by percentage) on record by tropical waves. On average,...