TROPICAL CYCLONE activity

2006 SUMMARY

The PEAC archives western North Pacific tropical cyclone numbers, track coordinates, and 1-minute average maximum sustained wind taken from operational warnings issued by the Joint Typhoon Warning Center (JTWC) of the U. S. Air Force and Navy, located at Pearl Harbor, Hawaii. Western North Pacific tropical cyclone names are obtained from warnings issued by the Japanese Meteorology Agency (JMA), which is the World Meteorological Organization's Regional Specialized Meteorological Center (RSMC) for the western North Pacific basin. The PEAC archives South Pacific tropical cyclone names, track coordinates, central pressure, and 10-minute average maximum sustained wind estimates from advisories issued by the Tropical Cyclone Warning Centers at Brisbane, Nadi, and Wellington. The numbering scheme and the 1-minute average maximum sustained wind estimates are taken from warnings issued by the JTWC. There are sometimes differences in the statistics (e.g., storm maximum intensity) for a given tropical cyclone among the agencies that are noted in this summary. For purposes of seasonal statistics, the JTWC archives Southern Hemisphere tropical cyclone activity for the 2007 cyclone season within the period July 2006 through June 2007.

The 2006 tropical cyclone season in the western North Pacific basin was overall below normal in most characteristics. There were fewer tropical storms (eight) than normal (ten), fewer typhoons (15) than normal (18), and the total number of all tropical cyclones (including depressions, tropical storms and typhoons) (27) was below normal (31). Two of the cyclones that were named by the JMA (Rumbia and Trami), were only classified as tropical depressions by the JTWC, and one of the cyclones (01W) was not named by the JMA but was classified as a tropical storm by the JTWC. The total number of super typhoons (those tropical cyclones with peak 1-minute sustained surface winds of 130 kt or more) was seven, which is three more than average. Some research indicates that there is a tendency for an above normal number of very intense typhoons during an El Niño year.

During 2006, the typhoon tracks were not typical of those commonly seen in an El Niño year. During El Niño there is usually a pronounced eastward shift in the genesis region of many of the tropical cyclones. The average “genesis location” (i.e. that latitude and longitude where a tropical cyclone first attains 25 kt on the JTWC best track) isnear Guam. During El Niño, so many of the cyclones form to the east of normal, that the average “genesis location” is shifted well eastward from Guam. The most pronounced El Niño shift of tropical cyclone activity occurs in the region east of 160°E and south of 20°N. The ratio of cyclones in this region between El Niño years versus La Niña years is 15 to 1. In late 2006 (September through December), the tropical cyclone activity looked more like that seen in a La Niña year than during El Niño. Nearly all of the cyclones formed to the west of Guam, and many of them subsequently moved westward to adversely affect the Philippines. Four typhoons in succession, beginning with Cimaron (22W) in late October, then Chebi (23W) in early November, then Durian (24W) in late November, and ending with Utor (25W) in mid-December had devastating effects in the Philippine archipelago.

Hurricane Daniel was the first named storm in the central Pacific in 2006.  Daniel formed 970 NM east-southeast of Hilo, Hawaii and dissipated well south of the Hawaiian islands.  On August 20, Ioke began taking shape as a tropical depression (01C) far south of Hawaii.  Three other cyclones (02C), (03C) and (04C) formed to the south-southwest of Hawaii during the 2006 season and dissipated without impacting any of the islands in the Central Pacific.  

In Micronesia, only three of the year’s tropical cyclones had noteworthy impacts: Ewiniar (04W), Ioke (01C), and Soulik (21W). On the first day of July, Ewiniar (while still a tropical storm) brushed past Yap Island bringing with it a damaging sea inundation. Ioke (a powerful hurricane that originated to the south of Hawaii in late August and later moved into the western North Pacific basin – thus changing into a typhoon) passed almost directly over Wake Island causing substantial damage there. In early October, Soulik (in its early developmental stages) passed near Majuro and Kwajalein. High surf associated with this cyclone pushed water onto the runway at Majuro International Airport that led to a contamination of many millions of gallons of drinking water.