30 JANUARY
THE NEW ZEALAND GAZETTE
445

CLIMATOLOGICAL TABLE—Summary of the Records of Temperature, Rainfall, and Sunshine for December 1968—continued

Air Temperatures in Degrees (Fahrenheit)

The "normal" refers to the present site of the instruments. The standard periods for normals are: for temperature 1931–60, for rainfall 1921–59, and for sunshine 1935–60. No normals are available for stations with only short records.

The sunshine recorder is not located at the station but is in the near vicinity.

NOTES ON THE WEATHER FOR DECEMBER 1968

General—December was a cool month, marked by an unusually high frequency of easterly and north-easterly winds, causing cloudy and wet conditions in the east and north of the North Island, while on the West Coast the weather was sunny with comparatively low rainfall. Nearly all the areas where rainfall had been inadequate in November received good rains in December, and farmers found it a particularly favourable month for growth. The main exception was North Otago, where conditions were too dry.

Rainfall—Rainfall was above average, mainly by 50 percent, over the North Island and in Nelson, Marlborough, North Canterbury, and parts of Central Canterbury. It was more than double the average in a large area extending from parts of Taihape through inland Hawke's Bay and parts of Gisborne and Bay of Plenty to Waikato; also in some areas in Northland and Nelson.

Over the remainder of the South Island rainfall was somewhat below average. It was less than half the average in coastal Otago and north Westland, and less than a quarter in the Alps, South Westland, and Fiordland. Milford Sound's total of 5.64 in. was the lowest for December in 40 years of record, and Otira's 4.26 in. was the lowest for December since 1934.

In the Taihape district, on the afternoon of the 7th, there were many violent thunderstorms associated with a slow-moving trough of low pressure. Exceptionally heavy rain over a period of 1–2 hours resulted in large slips and wash-outs near Mangaweka, with disruption of road and rail traffic for several days. At Waiouru 1.68 in. of rain was recorded in an hour.

Thunderstorms also were comparatively frequent over the North Island from the 23rd to the 30th.

Temperatures—Temperatures were 2–3 degrees below average in Northland and in eastern districts from Gisborne to Canterbury. Elsewhere they were close to or somewhat below average.

Sunshine—Sunshine was below average over nearly the whole of the North Island and in Nelson and Marlborough. In eastern and northern districts of the North Island the deficiency was 60–90 hours, with record low totals for December at Waihi and Gisborne. The 111 hours of sunshine at Whangarei was one of the lowest ever recorded in December or January in any part of New Zealand. Most remaining districts of the South Island were favoured with 20–50 hours above average sunshine.

Weather Sequence—The first nine days of December were very unsettled, with considerable rain in the North Island and the northern half of the South Island from a slow-moving trough of low pressure, associated later with a depression. The trough commenced to move on to the North Island from the north-east on the 1st, when it reached Northland and Gisborne. During this day and the next it brought rain to nearly the whole of the North Island as it moved south-westwards. This direction of motion continued on the 3rd, when the rain spread to parts of the South Island, with a temporary clearance north of Taupo and in some other areas. Somewhat similar conditions persisted on the next day, with the trough stationary through Cook Strait. A depression developed off the New South Wales coast on the 5th, and the trough commenced to move slowly north-eastward, with rain spreading again over the whole North Island. The depression soon reached a point just west of the North Island; and, as the front continued its slow north-eastward movement on the 6th and 7th, there were two very wet days in many areas. Worst hit was the Taihape district, where violent thunderstorms with very heavy rain over a period of about an hour caused slips and wash-outs, especially near Mangaweka, disrupting road and rail transport for several days. Conditions improved over the North Island on the next day. The depression now lay to the east, and a southerly change brought rain to the South Island, but on the 9th the rain was confined mainly to Hawke's Bay.

A large anticyclone covered the country during the 10th and 11th, with fine weather. For the next three days this anticyclone remained almost stationary, centred south of the Chatham Islands, while a depression west of the South Island drifted slowly north-eastward, to become eventually part of a trough west of Northland. Rain was reported at first in the south-west of the South Island, but the main falls were later, in the northern half of the North Island.

A tropical storm east of New Caledonia moved south-eastwards, and by late on the 15th it was centred 700 miles north-east of East Cape, where it remained stationary for the next three days, slowly losing intensity near the end of this period. These 4 days were notable for considerable rain and strong winds at times in Gisborne and Hawke's Bay, with some light rain also in Northland, while elsewhere the weather was fair or fine.

During the 19th and 20th an extensive belt of high pressure covered the whole country, with settled weather. For the next three days another trough of low pressure affected most of the country during its slow north-eastward movement. Two small centres of low pressure also developed on it. Some heavy rain was reported in Nelson on the night of 22–23 December. As a belt of high pressure extended once more across the South Island one shallow centre of low pressure remained stationary west of Northland. On the 24th rain affected mainly areas near Cook Strait.

During the holiday week, 25–31 December, an extensive belt of high pressure covered the South Island, while pressures were relatively low to the north-west. Winds over the country were mainly light, with easterly to north-easterly directions predominating in the north. Conditions were rather unsettled in northern and eastern districts of the North Island, with frequent showery periods and some thunderstorms and heavy downpours. In the South Island, Nelson and North Canterbury were also affected at times. However, the greater part of the country enjoyed settled weather.

(N.Z. Met. S. Misc. Pub. 107)

J. F. GABITES, Director.