Climate Update 60 - June 2004

June

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

Backgrounder
The world’s oceans and our climate
Alan Porteous, Phil Sutton, and Lionel Carter, NIWA

The ‘Ocean Conveyor’.

The circulation of the world’s oceans helps to keep the climate of the land masses relatively stable. Ocean currents have evolved over a long time – in spite of suggestions of near-instant climate change in the recent film The Day after Tomorrow, abrupt breakdown in ocean circulation is unlikely this century.
The circulation of the world’s oceans is driven by tidal forces, wind stress, and changes in the density of the water.

Checkpoint

Outlook and outcome – March 2004 to May 2004
Rainfall was lower than predicted in the west of the North and South Islands, in Northland, and in parts of the east and south of the North Island. In other areas, rainfall was normal or below normal as expected.
Air temperatures were average or below average as predicted in most places, although it was cooler than expected in the north and east of the North Island.
River flows were expected to be normal or above normal in western regions, normal or below normal in the east of the South Island, and near normal elsewhere.

June

Climate Update is a summary each month of New Zealand’s climate, including soil moisture and river flows.
June 2004 – Number 60
May’s climate: Mostly warm; wet in the north and east.

Climate

New Zealand Climate
Warm and wet in the east
May’s climate was much warmer than usual, with temperatures almost the same as in April 2004. Rainfall was well above average in parts of Auckland, Coromandel, and Bay of Plenty, and below average in Wanganui, Manawatu, Kapiti, and Wairarapa. Mean temperatures were above normal in most districts, especially Bay of Plenty and Gisborne.

Three-month outlook

The outlook for June 2004 to August 2004
Below average mean sea level pressures are expected to the south of New Zealand, with slightly enhanced westerly quarter winds, during winter 2004.
Mean three-month sea surface temperatures around New Zealand are likely to be near the long-term winter average.
Temperatures are expected to be average or below average for the southern two-thirds of the South Island, and average elsewhere.
Rainfalls are expected to be near normal in most regions, but tending to below normal in the northern North Island.

River flows

River flows
Streamflows were below normal in the southern North Island and in inland Southland. Flows were generally normal or above normal in western regions (except the Buller and Grey rivers), and near normal elsewhere.
 

Soil moisture

Diminished deficits
End of April soil moisture deficits in eastern regions of the South Island, and in Hawke’s Bay and Northland, were largely overcome during May. Parts of Otago remained at less than 50% total root zone moisture storage at the end of the month, although conditions were generally better than at the same time last year.
 
Soil moisture deficit in the pasture root zone at the end of May (right) compared with the deficit at the same time last year (centre) and the long-term end of May average (left).