Retrospective – April to June 2015 Outlook

During April - June 2015, lower than normal mean sea level pressures were expected to the east and northeast of New Zealand with positive mean sea level pressure anomalies west of New Zealand.  This circulation pattern was likely to produce anomalous westerly quarter wind flows.

Actual pressures were slightly higher than normal north of New Zealand and lower than normal over the South Island and south of the country. This pressure set-up produced more westerlies than normal.

Predicted rainfall: April – June 2015 rainfall is about equally likely to be in the near normal or above normal range in the west of the North Island. Rainfall totals for the season are about equally likely to be in the near normal or below normal range for the north and east of the North Island and the east of the South Island. In the north and west of the South Island, rainfall is most likely to be in the near normal range.

Outcome: Actual rainfall was well above normal in the west of both the North and South Island as well as in the Whakatane, Christchurch and Dunedin districts. Rainfall was below normal in the east of the North Island, Kaipara, Whangarei, the Far North, Kaikoura, Hurunui and Waimate.

Predicted air temperature: April – June 2015 temperatures are most likely to be in the above average range in the east and north of the North Island. For all remaining regions of New Zealand temperatures are about equally likely to be in the near average or above average range. As autumn progresses, cold snaps and frosts can still be expected from time to time in some parts of the country.

Outcome: Actual temperatures were above average in the west of the North Island, east of the South Island Whangarei, Waikato, Thames-Coromandel, Taupo, Buller, Central Otago and parts of the Southland. Temperatures were near normal elsewhere.