29 MAY

THE NEW ZEALAND GAZETTE

CLIMATOLOGICAL TABLE--Summary of the Records of Temperature, Rainfall, and Sunshine for April 1975--continued

|Station|HeightofStationAboveM.S.L.|Metres|Means of|Meanof A|DifferenceFromNormal|Absolute Maximum andMinimum|Maxi-mum|Date|Mini-mum|Date|TotalFall|No.ofRainDays|DifferenceFromNormal|MaximumFallAmount|Date|BrightSunshine|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|Franz Josef, March 1975|122|°C|19.1|11.4|15.3|+1.7|°C|25.7|13|4.8|27|944|19|+494|208|30|..|
|Brightlands Bay, March 1975|15|°C|20.1|15.2|17.7|..|°C|22.6|18|10.8|2|215|15|+59|64|4|..|
|Godley Peaks, Tekapo, March 1975|762|..|..|..|..|..|..|..|..|..|..|48|..|+2|..|..|..|
|Raoul Island, February 1975|38|24.4|20.6|22.5|+0.1|26.1|4|17.0|3|365|14|+210|209|26|138|

The “normal” refers to the present site of the instruments. Standard periods for normals are: Temperature 1931-60, Rainfall 1941-70, Sunshine 1941-70. No normals are available for stations with only short records.

*Indicates that the sunshine recorder is not located at the station but is in the near vicinity.

A rain day is a day with rainfall equal to or greater than 0.1 mm.

Where the extremes of temperature and rainfall have occurred more than once during the month, the date of the first occurrence is given.

NOTES ON THE WEATHER FOR APRIL 1975

General—April was marked by more frequent winds from a westerly quarter than usual. It was a warm month and predominantly dry in the North Island but wet in the South Island. Many farmers found conditions rather favourable but in parts of the North Island they found conditions too dry.

As a very deep depression passed just to the south of Southland on the 1st, strong northerly gales buffeted many areas, especially about Cook Strait. At the same time heavy rain brought the Southern Lakes to unusually high levels besides causing some local flooding further north.

Rainfall—In the North Island rainfall was mainly only half to three-quarters of the normal value. However, it was somewhat above normal in most western districts from Taranaki to Manawatu.

In the South Island rainfall was mainly above normal by up to 50 percent. However, it was below normal in some eastern districts, especially around Dunedin, and also in an area extending from Nelson city to Karamea.

It was a particularly wet month in Fiordland. Milford Sound received 1283 mm, a record total for April. The total for the 5th and 6th was 419 mm; and in the 14 days from 28 March to 10 April, 1173 mm were recorded.

Temperatures—Temperatures were mainly about 1°C above normal. The highest departures were in eastern districts of the South Island and in southern districts of the North Island. Unusually warm nights were experienced on 20-21 and 21-22 April. This was the 8th month with temperatures predominantly above normal. The average departure from September 1974 to April 1975 was 1½°C.

Sunshine—On the West Coast and in Southland and most of Otago sunshine was below normal by 25-50 hours. Elsewhere sunshine was mainly close to normal, but it was 15-30 hours above normal in Northland and Auckland and also in parts of Marlborough and Canterbury.

Weather Sequence—At the beginning of April a very deep depression passed close to Southland. Rain was general but light near the coast east of the ranges. Considerable falls were reported in the Alps and in Fiordland. Strong gales buffeted many areas, especially about Cook Strait. Temperatures were warm. By the 2nd the depression was centred far to the south of Campbell Island and a trough of low pressure was crossing the country. Rain was restricted mainly to the West Coast, the Southland coast, Northland, and the Bay of Plenty. On the following day, with a change to westerly to south-westerly winds, the rain persisted in the west and south of the South Island. During the next 3 days an extensive anticyclone covered the North Island but another depression was passing far to the south-west and the trough associated with it became stationary over Southland. The weather cleared temporarily on the West Coast and in Southland at first but deteriorated again on the 5th and 6th, with some particularly heavy rain in Fiordland. On the following day, with the passage of this trough over the remainder of the country, some rain was reported in most districts. From the 8th to the 11th pressures were again high over the North Island and rather low to the south of the country, causing a persistence of westerly conditions, with rain restricted mainly to South Westland and Fiordland. Temperatures were unseasonably warm at times in the east.

From the 12th to the 14th a large anticyclone over the South Tasman Sea moved towards New Zealand. With the development of southerly winds temperatures became cooler in the east with some showers at first. From the 15th to the 20th this anticyclone moved slowly across New Zealand and to the east. The weather was mainly fine with rising temperatures but showers were reported at times in Fiordland and on the Southland coast.

From the 21st to the 23rd an anticyclone was centred far to the east of the North Island while a complex trough of low pressure over the Tasman Sea crossed the country from west to east. Rain was fairly general west of the ranges and temperatures remained rather warm. During the next 2 days the trough became stationary to the north-east of Auckland while another trough moved on to Southland. The rain now extended also to districts east of the ranges. As the second trough crossed the remainder of the country on the 26th there was little further rain, but southerlies brought colder temperatures.

During the 27th and 28th an anticyclone over the Tasman Sea still extended on to the North Island, but a trough of low pressure moved on to the South Island from the south, with a small depression developing there. Considerable rain was reported in the Alps and on the West Coast with some also on the Southland coast. On the last 2 days of the month this small depression moved north-eastward, eventually crossing the North Island, while an anticyclone was centred to the south-east. Cold southerlies set in and the rain became fairly general. However, the weather soon cleared over most of the South Island and west of the ranges in the North Island.

J. F. DE LISLE, Director.

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