1856

THE NEW ZEALAND GAZETTE

No. 89

CLIMATOLOGICAL TABLE—Summary of the Records of Temperature, Rainfall, and Sunshine for August 1973—continued

| Station | Height of Station Above M.S.L. | Means of | Mean of A Max. and and B Min. | Difference From Normal | Absolute Maximum and Minimum | Air Temperatures in Degrees (Celsius) | Total Fall | No. of Rain Days | Difference From Normal | Maximum Fall Amount | Date | Bright Sunshine |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Takahe Valley, May 1973 | 762 | 5.8 | 0.2 | 3.0 | ... | 13.5 | 3 | -5.6 | 21 | 285 | ... | ... | 48 | 30 | ... |
| Takahe Valley, June 1973 | 762 | 1.8 | -3.7 | -1.0 | ... | 10.0 | 3 | -10.0 | 15 | 162 | ... | ... | ... | ... | ... |
| Takahe Valley, July 1973 | 762 | 2.3 | -4.9 | -1.3 | ... | 8.0 | 21 | -9.0 | 13 | 36 | ... | ... | ... | ... | ... |
| Mid Dome, July 1973 | 386 | 8.6 | -1.5 | 3.6 | +0.4 | 15.1 | 22 | -5.5 | 13 | 36 | 9 | -25 | 12 | 24 | ... |
| Moa Creek, July 1973 | 427 | 5.5 | -6.0 | -0.3 | -0.7 | 10.2 | 22 | -9.3 | 3 | 14 | ... | -4 | ... | ... | ... |

The “normal” refers to the present site of the instruments. Standard periods for normals are: Temperature 1931–60, Rainfall 1921–50, Sunshine 1935–60. 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 AUGUST 1973

General—August resembled July in having an unusually high frequency of easterly winds, but it was much wetter and also rather cloudy.

It will be remembered especially for the heavy snow on the 5th and 6th in the upper Canterbury Plains and parts of the Mackenzie Basin and inland North Otago. The greatest depth over the plains was 3 feet, as at Methven, but it was about double this value in some areas, as at Sherwood Downs, 10 miles north of Fairlie; in these areas it was the heaviest snow since July 1945. Thousands of stock were lost, in spite of a large rescue operation. Power and telephone lines came down and some secondary roads were blocked for several days.

For a considerable part of the country this was the first wet month after 9 dry months, and many farmers appreciated the rain for this reason.

Rainfall—Rainfall was above normal over most of the South Island. In an area extending 40 miles inland from just west of Christchurch to just north-west of Dunedin it was 3–5 times the normal value; for some stations this was the wettest August in 60 years of observation.

In the North Island rainfall was mainly close to normal. However, it was more than double the normal value in northern Hawke’s Bay and the southern part of the Gisborne district.

In Canterbury and North Otago the wettest period coincided with the snow on the 5th and 6th. Akaroa received 301 mm in these 2 days, and many stations received 100–200 mm. Some heavy falls were also recorded in northern Hawke’s Bay on the 7th and 8th, including a 2-day total of 92 mm at Wairoa, causing flooding there.

Temperatures—Temperatures were above normal by about 1°C over the North Island and they were also somewhat above normal in northern and western districts of the South Island. They were colder than normal by up to 2°C in inland Canterbury.

Snow covered considerable areas of the high country of the central North Island as a result of a fall on the 21st and 22nd.

Sunshine—Sunshine was mainly 20–50 hours below normal, with highest departures in some eastern districts from Canterbury northward. However, it was close to normal in Otago and Southland.

Weather Sequence—At the beginning of August an anticyclone was centred east of the South Island while pressures were low to the north and north-west. The weather was fair, apart from some showers in Northland, and cold. During the next 2 days a depression over the North Tasman Sea moved southward across the country with an associated trough of low pressure, bringing fairly general rain. As this depression moved away to the east another one over the South Tasman Sea moved on to the South Island, bringing rain to the West Coast on the 4th. This depression moved slowly north-eastward over New Zealand on the 5th and 6th, while an intense anticyclone developed over Campbell Island. There was general precipitation in the cold, strong south-easterlies and heavy snow was reported on the upper Canterbury Plains and in parts of inland Otago. During the next 2 days this depression continued to move north-eastward rather slowly. Rain at first affected areas east of the ranges in both islands and later the whole of the North Island. Some heavy falls were reported in Gisborne and northern Hawke’s Bay with flooding at Wairoa. Temperatures remained cold.

During the 9th and 10th depressions passed rapidly close to the South Island, causing rain mainly on the West Coast but also in Southland, with some light falls in Otago and South Canterbury. For the next 3 days a depression over the North Tasman Sea moved southward, becoming complex, while a belt of high pressure over Tasmania extended towards Campbell Island. The weather was milder with general rain, including some considerable falls. Flooding was reported in parts of Northland. During the 14th and 15th the depression moved away to the south-east while pressures were high to the north. At first rain was reported in most places west of the ranges but later it affected only parts of the West Coast.

On the 16th and 17th an anticylcone centred near Campbell Island moved eastward, while a depression lay east of Northland, and another complex depression covered the Tasman Sea. Rain was reported over most of the North Island, with some considerable falls in eastern districts. Temperatures were again rather cold. A ridge of high pressure extending from the south-east brought a temporary improvement to most districts on the 18th. However, during the next 3 days two depressions over the Tasman Sea moved in succession across central New Zealand while pressures rose in the south, causing a southerly change on the last day. Rain was fairly general from Christchurch northward. On the 22nd a shallow complex depression lay over the North Island while pressures remained high to the south and cold south-easterlies covered most of the country. Rain was reported east of the ranges from Christchurch northward and also in the Auckland district. Considerable snow fell on the high country of the central North Island, with a light fall also in parts of Canterbury. As the depression moved away to the east on the following day conditions remained somewhat similar.

During the 24th and 25th an intense anticyclone moved across the country to the east, bringing mainly fair weather. On the 2 following days the anticyclone was centred to the east of Chatham Islands while depressions passed far to the north and also close to Southland. In the north-easterlies rain was reported in Coromandel and Auckland. Rain also affected Taranaki. Nelson, and the West Coast. For the next 2 days a complex depression covered the Tasman Sea. In the northerlies temperatures became very mild and rain was reported on the West Coast. For the last 2 days of the month one of the centres moved across the northern part of the South Island. Rain became fairly general but there was little east of the ranges north of Christchurch. Temperatures remained very mild.

J. F. de LISLE, Acting Director.

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