Tropical Cyclone activity expected to be above average

October 14, 2015

The weather in the tropical Southwest Pacific is becoming more active as we get closer to the formal start of the tropical cyclone season on 1st November. With a strong El Nino in effect, cyclone activity is expected to be above normal this season, spreading further east than normal and increasing the risk for the majority of Pacific Island nations.

Every year MetService works alongside NIWA and national meteorological services from other Pacific nations to produce a Tropical Cyclone Outlook for the upcoming season. The outlook for the 2015/2016 season indicates that 11 to 13 tropical cyclones are expected in the Southwest Pacific, with at least six of those expected to be severe (Category 3 or higher). The average number of named tropical cyclones for previous seasons is about 10, based on the past 30 years. Although the tropical cyclone season typically runs from 1 November through until the end of April, weather doesn’t always follow a rigid calendar and tropical cyclones have been known to form as late as June.

MetService meteorologists are already watching the tropics closely for any signs of early development and have begun regular briefings to the Ministry of Foreign Affairs and Trade, who provide disaster relief in the Pacific.

Around the globe, the monitoring and forecasting of tropical systems is looked after by a Regional Specialized Meteorological Centre (RSMC) or a Tropical Cyclone Warning Centre (TCWC), depending on the location of the cyclone. TCWC Wellington, based at MetService, has warning responsibility for the area that extends from 160E to 120W and between 25S and 40S. Although it is very rare for any tropical cyclones to form in TCWC Wellington’s area of responsibility, fully-fledged tropical cyclones do arrive from the neighbouring Brisbane or Nadi areas and they often retain their cyclone status until near 30S. Sometimes an ex-tropical cyclone will approach New Zealand and Severe Weather Watches and Warnings need to be issued. Even if land areas are not affected, warnings are still issued for vessels over the open sea.

On average, New Zealand experiences about one ex-tropical cyclone a season,and the risk is slightly higher than normal this season.

For further information please contact:
Chris Noble Manager Specialist Weather Services (04)4701175

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