Global setting and climate outlook
Global setting and climate outlook
El Niño-Southern Oscillation remains neutral
Pacific Trade Winds about and west of the Date Line were enhanced in October, and the Southern Oscillation Index was high. In spite of these La Niña-like characteristics of the Tropical Pacific atmosphere, ENSO remained in neutral phase during the month, and is very likely to continue in this state through summer. Sea surface temperatures in the equatorial west Pacific remained near normal during October.
Sea surface temperatures(SST) around New Zealand
Sea surface temperatures (SSTs) are now a little below average in the New Zealand region. The October SST anomaly in the New Zealand quadrant was –0.3 °C with a three month (August to October) average anomaly of –0.2 °C. Sea surface temperatures around New Zealand are expectedto be near normal over the next three months.
Outlook for November 2008 to January 2009
In the New Zealand region, mean sea level pressures are likely to be higher than normal, especially east of the country, resulting in lighter winds than usual over most regions. Air temperatures are likely to be above average in most regions of the country, but near average in the eastern South Island. Rainfall is likely to be near normal in the north and east of the North Island, and normal or below normal elsewhere. Normal or below normal soil moisture levels and stream flows are likely in most regions, apart from the east of the South Island where below normal conditions are likely.
With ENSO-neutral conditions, there is a 4 out of 5 chance of an ex-tropical cyclone passing within 500 km of the country between November and May, with the highest risk in the Northland and Gisborne districts.