Climate Update 61 - July 2004

July

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

Backgrounder
Fifteen decades of climate record
The New Zealand instrumental air temperature record goes back to 1853 and provides us with a valuable indication of how the climate has changed since the mid 19th century.
The figure below shows the mean temperature anomaly for spring (green), summer (yellow), autumn (pink), and winter (blue) for each decade from the 1850s. Note that the first and last decades are incomplete.

Checkpoint

Outlook and outcome – April 2004 to June 2004
Rainfall was near normal as predicted in many areas, but was higher than predicted for the northern North Island. Bay of Plenty and East Cape and the northern and southern extremities of the South Island were wetter than predicted.
Temperatures were near average in the North Island, in line with the outlook for April to June, but higher than forecast in most of the South Island.
Soil moisture levels were below normal as predicted in north Otago and coastal Canterbury.

July

Climate Update is a summary each month of New Zealand’s climate, including soil moisture and river flows.
July 2004 – Number 61
June’s climate: June rainfalls were above average in the west of New Zealand, but very low in Canterbury. A warm month with high temperatures in the eastern South Island.

Climate

New Zealand Climate
Above average temperatures and wet in the west
Air temperatures of more than 0.5 °C above average in most places, and more than 1.0 °C above average in many places, ranked last month as the fifth warmest June on record. The largest temperature anomaly was at Hanmer Forest, with +2.6 °C. Rangiora and Christchurch Airport recorded their highest June mean temperatures.
More northwesterlies than usual produced the milder conditions.

Three-month outlook

The outlook for July 2004 to September 2004
During the next three months, mean sea-level pressures are expected to be near average in the Tasman Sea and over New Zealand, with slightly enhanced westerly quarter winds to the south of the country during late winter. Sea surface temperatures are likely to be near or slightly above average around New Zealand.
Temperatures are expected to be average or above average in the North Island, and average in the South Island.
Rainfalls are expected to be near normal in all regions.

River flows

River flows
High river flows in the west
Stream flows were above normal in the west and the centre of the North Island, East Cape, and Wairarapa, and in northern, alpine, and southwest South Island. Stream flows were below normal in coastal Canterbury and Marlborough, and in northern Hawke’s Bay, and normal elsewhere.
 

Soil moisture

Dry spots in Kaikoura and Canterbury
Low rainfalls in Kaikoura and in parts of mid Canterbury have delayed soil moisture recharge to normal levels in those areas. Elsewhere in the country, soil moisture levels are near or above normal, except in parts of Otago, where soil moisture deficits were greater than normal at the end of June.
 
Soil moisture deficit in the pasture root zone at the end of June (right) compared with the deficit at the same time last year (centre) and the long-term end of June average (left).