Climate Update 49 - July 2003

29 March 2007 - 3:34pm

Science Centres: Climate

July

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder
Low SOI does not signal an El Niño The Southern Oscilliation Index dropped surprisingly to –1.4 during June indicating a subtle change in developments from the movement towards La Niña like conditions that was evident in May. Meanwhile, sea surface temperatures (SST) in the eastern tropical Pacific along the Equator fell to a degree below normal during May and June.

Checkpoint
Outlook and outcome – April 2003 to June 2003 Rainfall occurred as predicted over much of the country apart from the northeast of the North Island where it was above normal and parts of Waikato to north Auckland which were drier than normal. Temperatures were expected to be near average over the North Island and the northern South Island, and average or below average elsewhere. Resulting temperatures were above average almost everywhere. Below normal river flows occurred in the eastern regions of both islands as predicted.

July
Climate Update is a summary each month of New Zealand's climate, including soil moisture and river flows. July 2003 – Number 49 June’s climate: Warmest June on record. June’s river flows: June stream flows variable. Soil moisture levels: Soils mostly at field capacity. Three month outlook: A mild late winter is expected. Checkpoint: How well are we doing with our predictions? Backgrounder: Winter chilling. How does June 2003 compare to previous years? This issue of the Climate Update is available as a PDF.

Climate
New Zealand Climate Warmest June on record June was the warmest recorded in New Zealand since reliable records began over 150 years ago. Temperatures reached more than 3 °C above normal in some inland sheltered areas of the eastern South Island. The June national average temperature of 10.3 °C was 2.0 °C above normal. Only June 1971 (10.2 °C) was anywhere near as warm.

Three-month outlook
The outlook for July to September 2003 A mild late winter is expected, with above average temperatures in all districts except the east of the South Island, where above average or average temperatures are expected. Despite this, typical winter cold spells are also likely, with frosty conditions at times in inland places. Local sea surface temperatures are likely to remain above average and local circulation patterns are expected to favour an enhanced westerly wind flow. Normal or below normal rainfall is expected in the east of the North Island.

River flows
New Zealand River Flows June stream flows variable June streamflows were below normal in Northland, Coromandel, the east coast of both islands, and Southland. Flows were near normal for rivers in the west and south of the North Island and were above normal for many Nelson and South Island west coast rivers.

Soil moisture
Soil moisture Soils mostly at field capacity By the end of June soils were mostly at field capacity in the North Island (apart from an area of south Wairarapa), and in the north, west and south of the South Island. Lower than normal rainfall in the east of the South Island slowed soil moisture recovery in some areas.