Climate Update 57 - March 2004

March

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

Backgrounder
Dr Phil Sutton, Physical Oceanographer, NIWA, Wellington
New Zealand is a group of small islands in a large ocean, and our climate is dominated by what happens beyond our shores. Research into ocean-atmosphere interactions is a key part of determining why our climate behaves the way it does.

NIWA marine technician John Hunt checks an Argo float ready for deployment between New Zealand and Chile.

Route map for Kaharoa.

Checkpoint

Outlook and outcome – December 2003 to February 2004
Rainfall was near normal or below normal, as predicted, in the eastern South Island and in Southland, but above normal in most other districts.
Air temperatures were higher than predicted in the east and north of New Zealand, while they were average or below average elsewhere as forecast.
River flows were below normal as predicted in the east of the South Island and in Bay of Plenty and Northland.

March

Climate Update is a summary each month of New Zealand's climate, including soil moisture and river flows.
March 2004 – Number 57
February’s climate: Exceptionally wet with devastating floods in the North Island.

Climate

New Zealand Climate
Mean temperatures were up to 2.5 °C below normal in the Southern Lakes, Central Otago, and inland Canterbury, and below normal in most other regions. The only warm spot in the country was Hawke’s Bay, where temperatures were slightly above average.

Three-month outlook

The outlook for March 2004 to May 2004
Below average mean sea-level atmospheric pressures to the south of the country may somewhat enhance westerly quarter winds through autumn. This is likely to bring relatively cool conditions to New Zealand and above normal rainfall in western areas.

River flows

Record high river flows
February streamflows were at highest known levels for February over much of the North Island and in the northern South Island. Elsewhere, above normal flows occurred in Bay of Plenty, East Cape, Hawke’s Bay, and most of the South Island alpine-fed rivers. Flows were normal to below normal in the Maniototo and coastal Southland regions.

Soil moisture

Saturated soils in the north and west
The heavy rain and resulting floods dominated soil moisture changes in February, particularly in the North Island. Topsoils in eastern regions of the South Island received welcome rain, with moisture levels in the total root zone improving to near average for this time of year.

Soil moisture deficit in the pasture root zone at the end of February (right) compared with the deficit at the same time last year (centre) and the long-term end of February average (left).