NIWA Outlook: October, November, December 2013

Overview

The equatorial Pacific Ocean continues in a neutral state (neither El Niño nor La Niña), with recent cooler-than-normal sea-surface conditions (La Niña-like) in the eastern tropical Pacific having weakened.

International guidance indicates that ENSO-neutral conditions are the most likely outcome for the next three months (October–December).

In the New Zealand region, higher pressures than normal are forecast to south of the country and lower pressures than normal are forecast in the Australian Bight extending eastwards into the central Tasman. This circulation pattern is expected to produce northerly quarter flows over the north of the country, and a slightly enhanced easterly flow over the lower South Island.

After another warm quarter, near or above average temperatures are expected to continue across the country for the coming three months. However, frosts may occur in some areas from time to time. Sea surface temperatures are expected to remain above average overall around New Zealand.

Outlook Summary

Temperatures over the October - December period as a whole are most likely (50% chance) to be above average in the east of the North Island and the north of the South Island. In all other regions, average or above average temperatures have near equal likelihood of occurring. The chances of below normal temperatures across all regions is 10-20%.

Rainfall totals over the October - December period as a whole are equally likely (40% chance) to be normal or above normal in the north of the North Island, and less likely (20 % chance) to be below normal. For all remaining regions of New Zealand, near normal rainfall totals are most likely (45-50% chance).

Soil moisture levels are equally likely (40% chance) to be normal or above normal in the north of the North Island, and most likely to be near normal for all other regions (40-50% chance).

River flows are equally likely (40% chance) to be normal or above normal in the north of the North Island, and most likely to be near normal for all remaining regions (45% chance).

SCO_Oct2013_301913.pdf

ENDS

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