Outlook - March to May 2014

The equatorial Pacific Ocean continued in a neutral ENSO-state (neither El Niño nor La Niña) in February 2014.

During March–May 2014, mean sea level pressures are expected to be lower than normal to the north of the country, with higher pressures than normal to the southeast of New Zealand. This circulation pattern is likely to be associated with anomalous north-easterly flows over the North Island and anomalous weak easterly flows over the South Island.

March–May temperatures are most likely to be near average for all regions of the country. As autumn progresses, cold snaps and frosts can be expected from time to time in some parts of the country. Sea surface temperatures are expected to be near average for the coming three months around New Zealand.

March–May rainfall is likely to be near normal or below normal for the north and west of the North Island, and for the north, west and south of the South Island. For the eastern regions of both Islands, 3-month rainfall totals are most likely to be in the near normal range.

Soil moisture levels and river flows are likely to be below normal in the north and west of the North Island and in the west and south of the South Island, near normal or below normal in the north and east of the South Island, and near normal in the east of the North Island.

For the tropical cyclone season (November – April), the risk of an Ex-Tropical Cyclone (ETC) approaching New Zealand is expected to be close to normal. Based on the long-term record, ETCs come within 550km of New Zealand for 9 out of every 10 years. However, the most likely period is during February-April, so further events (following on from ex-tropical cyclone June in January) cannot be ruled out. For ENSO-neutral years (the current situation), any ETCs approaching the North Island are twice as likely to pass to the east of Auckland as to the west of the city.