Climate Update 44 - February 2003

February

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

Backgrounder

Pacific ENSO signal
The El Niño event has passed its peak and is now waning. Equatorial subsurface temperature anomalies have weakened east of the dateline and westerly zonal wind anomalies have reduced in horizontal extent to a region near the dateline.

Checkpoint

Outlook and outcome – November 2002 to January 2003
Rainfall was near normal or below normal in many areas of the country as expected, but in the west and south of the South Island it was drier than predicted.
Air temperatures were expected to be near average for the North Island and the north of the South Island, and average or below average elsewhere. Temperatures were lower than expected over the North Island and were close to those predicted for the South Island.
River flows were higher than predicted over most of the North Island and the north of the South Island.

February

Climate Update is a summary each month of New Zealand's climate, including soil moisture and river flows.
February 2003 – Number 44
January’s climate: This month was drier than normal apart from northern North Island regions.
January’s river flows: January streamflows mostly low.
Soil moisture levels: North Island soils from Waikato south were very much drier than normal by the end of January.
Three month outlook: Early autumn is expected to be influenced by enhanced antocyclone activity over the Tasman Sea.
Checkpoint: How well are we doing with our predictions?
Backgrou

Climate

New Zealand Climate
Wet in some northern regions; dry elsewhere
Rainfall was at least 150 % of average in Northland, Auckland, Coromandel, and western Bay of Plenty, and double average in eastern parts of Northland and Coromandel. Whitianga recorded its highest January rainfall since records began in 1991.

Three-month outlook

The outlook for February 2003 to April 2003
Early autumn is expected to be influenced by enhanced anticyclone activity over the Tasman Sea with episodes of stronger than normal southwesterly winds across New Zealand.

River flows

New Zealand River Flows
January streamflows mostly low
January flows were below normal in many areas. Only Northland, inland Bay of Plenty, and East Cape recorded high flows.

Soil moisture

Soil moisture
North Island soils from Waikato south were much drier than normal by the end of January. The soil moisture deficit was particularly severe in eastern areas, Manawatu, and Horowhenua. Northern and eastern South Island regions also had severe soil moisture deficit. Significant rainfall during January improved the moisture levels in upper North Island soils.

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