Retrospective: March-May 2018 Outlook
For March – May 2018, the atmospheric circulation around New Zealand was forecast to be characterised by lower than normal atmospheric pressure northwest of the country, extending over parts of New Zealand, unsettled conditions especially for the North Island, and weak northeasterly quarter flow anomalies. Actual pressures were lower over and to the south of the country. This pressure set up led to an enhanced westerly flow across the country.
Predicted air temperature: March – May 2018 temperatures were forecast to be above average for all regions of New Zealand with high confidence.
Outcome: Actual temperatures were above average across the North Island and coastal parts of the South Island. The remainder of the South Island saw near average temperatures.
Predicted rainfall: For March – May 2018, rainfall totals were forecast to be above normal in the North Island and in the north of the South Island and about equally likely to be near normal or above normal the west and east of the South Island.
Outcome: Actual rainfall was above normal for large parts of the country. The exceptions were the north of the North Island, Gisborne as well as parts of the West Coast and Southland where rainfall was near normal.