16 JULY
THE NEW ZEALAND GAZETTE
2747

THE WEATHER IN NEW ZEALAND IN MAY 1984

General—May was cool and dry over most of New Zealand. Winds in the north were very close to normal for May, the only notable point being a slight increase in winds from the easterly quarter. In the south there were significantly fewer north-westerly winds than usual and more light winds than normal for May.

High winds in the Bay of Plenty and Hawkes Bay region on the 1st and 2nd caused some kiwifruit and apple losses, and caused extensive power cuts and minor damage in the Thames area on the 24th.

Pressures were higher than normal over the whole country this month.

Most farmers reported excellent stock health and good growth until the end of the month when extensive frosts slowed growth considerably.

Rainfall—Most of the country was drier than usual this month. The only areas to have average or above average rainfall were isolated coastal areas in Northland and Gisborne in the North Island, and some eastern coastal areas, Otago and Southland in the South Island. These areas generally had between normal and 150 percent of normal rainfall.

The Bay of Plenty region was quite dry with many stations recording less than half their normal rainfall, while the rest of the North Island had between about 50 percent and 80 percent of normal rainfall. In the South Island most stations also recorded between 50 and 80 percent of normal rainfall.

Temperatures—May was a cool month. Mean temperatures were about 0.5°C cooler than usual for the time of year.

Canterbury, Central Otago and parts of Westland and Fiordland were particularly cool, with mean temperatures between 1°C and 2°C, and mean minimum temperatures up to 3°C, cooler than usual for May. North Island temperatures were closer to normal with southern Bay of Plenty and Rotorua about 1°C cooler than usual but the rest of the Island up to 0.5°C cooler than normal.

Anticyclonic conditions brought calm, clear weather and heavy frosts to many parts of the country between the 20th and 23rd. These were particularly severe in many parts of the South Island and some central areas of the North Island. During this period record air minima for May were established at several stations, including Christchurch (−4.5°C), Milton (−7.0°C) and New Plymouth (−0.6°C). Other sites with near-record minimum temperatures were: Dunedin airport (−7.5°C), Tokirima (−5.7°C), Waikeria (−5.2°C) and Hokitika (−1.5°C).

Sunshine—Sunshine hours were close to normal over most of the country this month. Central New Zealand and eastern areas recorded about 25 hours more than usual for May, while other areas had down to 20 hours less.

Among those stations recording greatest departures from normal were: Gisborne (+26 hours), Kelburn (+26 hours), Nelson (+29 hours), Timaru (+21 hours), Invercargill (−20 hours) and Rotorua (−14 hours).

THE WEATHER SEQUENCE, MAY 1984

1–7 May
At the beginning of the month an anticyclone lay centred over south-eastern Australia and a strong south-westerly flow covered New Zealand. A front travelling within this flow brought showers to most areas as it crossed the country to lie to the east on the 2nd.

By the 3rd the anticyclone had moved eastward and was centred close to Lord Howe Island. Fine weather prevailed except in some isolated areas of Southland and South Otago. The anticyclone had moved to lie centred over Northland by the 5th and a front within the westerly flow to the south began to approach the South Island. Rain fell in the south and west on the 5th and there were light falls in other areas on the 6th and 7th as the front crossed the country and the anticyclone moved away to the east.

8–14 May
During the 7th a small depression began to develop off the east coast of Australia and by the 8th this lay in the mid-Tasman Sea. Its associated frontal system brought rain to western and central areas on the 8th and rain spread to most parts of New Zealand on the 9th. The depression became stationary to the west of the country and weakened slightly during the 10th and the rain cleared from most districts. A complex trough crossed the South Island and fronts within this brought rain to western areas on the 13th and 14th.

15–21 May
A ridge from an anticyclone centred over eastern Australia extended over Northland during the 15th. The weather was generally cool and clear until the 17th, although a few showers remained in some isolated areas of the South Island. On the 17th a trough began to approach the South Island and rain fell in western and southern areas. By the 18th the rain had become widespread in the south and west of both islands as the trough began to cross the South Island. Temperatures were very cool. Although showers remained in some eastern areas on the 20th the weather was generally fine but cool on the 20th and 21st as an anticyclone, centred south-west of New Zealand extended a ridge over the country.

22–31 May
Although the ridge still covered New Zealand on the 22nd a small depression began to develop to the east of the North Island and there were showers in Northland on the 22nd and in most parts of the North Island on the 23rd. The depression became part of an eastward moving trough and as this complex trough moved on to New Zealand rain became widespread. The trough became slow moving over the country and associated cold fronts brought rain to many areas, especially in the North Island, until the 28th. By the 28th the trough lay well to the east and a cool, south-west airflow, associated with an extensive anticyclone centred near Tasmania, covered the country. The weather was generally fine and cool until the 30th, although fronts travelling within the flow brought showers to many districts at times during the last 3 days of the month.

PROPOSED DISCONTINUATION OF THE WEATHER SEQUENCE

Daily weather information, including maps, is now available through various media. The Meteorological Service is therefore proposing to discontinue publishing the Weather Sequence as above, though the Climatological Table and written summary will continue in the Supplement to the New Zealand Gazette.

People having a special need for the Weather Sequence as currently published are invited to write to—

The Director,
New Zealand Meteorological Service,
P.O. Box 722,
Wellington,

by 30 September 1984.

J. S. HICKMAN, Director.

Price 50c

BY AUTHORITY: P. D. HASSELBERG, GOVERNMENT PRINTER. WELLINGTON, NEW ZEALAND—1984
1588411—84PT