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Hurricane Season 2003 Statistical normals of storm frequencies for the North Atlantic hurricane season, based on the 1950-2000 average, are 10 named storms, 6 of which become hurricanes, and 2 of those typically become intense hurricanes. Last year in 2002, there were 12 named storms, 4 of which became hurricanes, and 2 of those became intense hurricanes. Only one of the hurricanes, Lili, made landfall while still a hurricane. Although the number of named storms exceeded the normal seasonal total, the El Ni�o event that was then present, and still is, kept the number of hurricanes to below normal levels. In spite of this, some portion of the U.S. East and Gulf coasts from the Lower Texas coast to Cape Hatteras was impacted by these storms. This is likely to be the case again this year. El Ni�o is an
occurrence of warmer than normal sea surface temperatures in the
equatorial Pacific Ocean. This year the warmer waters extend from Indonesia eastward across the Central Pacific but they are now less than 2� C warmer than usual. In the eastern Tropical Pacific, the sea surface temperatures (SST's) are near or slightly cooler than normal at and south of the equator (see figure 1). This El Ni�o event is different from the previous one (1997-1998), during which the Tropical Pacific waters were much warmer, primarily in the central and eastern protions of the equatorial waters (see figure 2).
We must keep in mind the fact that these two El Ni�o episodes are different when looking to the upcoming hurricane season. Additionally, the current El Ni�o appears to be weakening and sea surface temperatures may become near normal in the equatorial region of the Pacific Ocean by the first few months of hurricane season. The influence on this year�s El Ni�o on the summer time high level wind pattern across the North Atlantic Ocean basin is forecast to be in the form of upper level high pressure areas that move slowly from west to east across the subtropical latitudes (20-35 degrees north latitude) separated by low pressure troughs. These troughs of weak upper air low pressure should drop into the tropical latitudes (0-20 north latitude) at various times and disrupt the development of some tropical disturbances. Additionally, it is quite likely that a few of the named storms will develop out of mid-latitude cyclones located east of Bermuda that form tropical characteristics but remain inconsequential due to their tracks staying well away from land and out of major shipping lanes. As a result, we expect an above normal number of named storms this year. Near or slightly less than the normal number of storms are forecast to reach hurricane strength. Of those, 3 are expected to become intense. Most of these storms should form in the western North Atlantic region with fewer forming farther to the east in the general vicinity of the Cape Verde Islands. Further weakening of El Ni�o during the remainder of the year would cause the latter half of this year�s hurricane season to be more active than the earlier half. 2003 Hurricane Season Forecast
Normal Forecast 10 12-14 6 6 3 3
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