Climate Update 51 - September 2003

September

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

ENSO remains quiet
The Equatorial Pacific atmosphere and ocean surface conditions suggest that the El Niño-Southern Oscillation (ENSO) was in a neutral state in August. The current neutral conditions are likely to remain through to the end of summer 2004.
The current three month value of the SOI is –0.5, while the SOI at the end of August was –0.4.

Checkpoint

Outlook and outcome – June 2003 to August 2003
The expected mild winter was experienced in most places. Buller was cooler than predicted. It was drier than expected in central and western North Island and eastern South Island. Elsewhere rain was as expected.
Soil moisture levels were normal as expected in most regions, but below average in south Canterbury and north Otago, and slightly below average in Manawatu and Horowhenua.
River flows were expected to be normal in northern and western regions, and normal or below normal in eastern districts.

Climate

New Zealand Climate
The end of a mild, mainly dry winter
August was settled, and drier than normal in many inland and western regions, but wetter than usual in some areas exposed to the east. Temperatures were near or above average in most places, the exception being parts of Central and south Otago.
Dry in many places
Central and western areas of the North Island from Waikato to Kapiti had less than half their normal August rainfall. Levin recorded only 19 mm, its lowest August total since records began in 1895.

Three-month outlook

The outlook for September to November 2003
A mild spring is expected, with above average temperatures over all the North Island and north of the South Island, with average or above average temperatures over the rest of the South Island.
Normal or below normal rainfall is expected in the east of both islands, while normal or above normal rainfall is expected in western areas of both islands and in Northland.

River flows

New Zealand River Flows
Low flows in central and southern regions
August streamflows were above normal in Northland, Coromandel, East Coast, Poverty Bay, and Hawke’s Bay. Flows were below normal in the rest of the North Island and nearly all of the South Island. Exceptionally low flows occurred in southern Waikato, the south and west of the North Island, and parts of Otago.

September

Climate Update is a summary each month of New Zealand's climate, including soil moisture and river flows.
September 2003 – Number 51
August’s climate: August was mild and dry over much of the country, but cold in Central Otago.

Soil moisture

Soil moisture
Some relief for soils in the north and east
Soils in Northland, Bay of Plenty, East Cape, Hawke’s Bay, and north Canterbury were at field capacity at the end of August following the heavy rain. The area of soils at less than field capacity in Marlborough was smaller than last month, but coastal soils had become drier and had less than 50 percent storage capacity.