TROPICAL CYCLONE SUMMARY

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 North Pacific tropical cyclone names are obtained from warnings issued by the Japanese Meteorology Agency (JMA). 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 when appropriate.

During the calendar year 2005, the JTWC numbered only 25 tropical cyclones in the western North Pacific. The JMA named only 23 of these. Normally there are approximately 31 numbered tropical cyclones in the western North Pacific basin during a calendar year, with a breakdown of 18 typhoons (TY), 10 tropical storms (TS) and 3 tropical depressions (TD). The TY-TS-TD breakdown for 2005 was 16, 8, and 1, respectively. In addition to a reduction in the annual number of tropical cyclones in the western North Pacific basin during 2005, the region of tropical cyclone formation was pushed well to the west of normal. During 2005 no tropical cyclones formed south of 20°N and east of 160°E; a region designated as the “El Niño Box” by Lander (1994) (Fig. 2). Tropical cyclone formation is observed in the “El Niño Box” primarily during El Niño years; almost no tropical cyclones form in this region during non-El Niño years. Only one tropical cyclone, Tropical Storm Nalgae, formed north of 20°N and east of 160°E during 2005. The typhoon season of 2005 ended with a whimper on December 18 when the JTWC issued the final warning on unnamed Tropical Cyclone 25W as it dissipated over water to the southeast of Ho Chi Minh City.