CLIMATOLOGICAL TABLE—Summary of the Records of Temperature, Rainfall, and Sunshine for April 1957—continued

†Observations for 21 days.

LATE RETURNS

Dannevirke, March, 1957... 685 71·9 53·1 62·5 ... 83·8 3 40·5 31 5·64 13 +2·83 1·40 11 ...
Appleby, Nelson, March, 1957 ... 57 71·4 54·7 63·0 +2·8 79·2 14 44·8 21 4·48 15 +2·40 1·10 18 ...
Eyrewell, March, 1957 ... 520 68·9 50·4 59·6 ... 81·2 15 39·3 31 4·46 15 +1·70 1·27 10 ...
The Hermitage, Feb., 1957 ... 2,510 70·6 48·8 59·7 +3·6 80·0 4 35·0 27 12·43 7 −2·75 5·33 25 167
The Hermitage, March, 1957 ... 2,510 63·1 46·5 54·8 +0·7 81·0 3 33·0 21 8·00 14 −7·69 2·45 19 119
Tara Hills, Omarama, Mar., 1957 ... 1,600 66·9 47·9 57·4 +1·2 86·0 4 31·6 31 2·50 16 +0·68* 0·77 6 123

NOTE—At stations where departures from normal have an asterisk, the temperature record has been maintained for less than ten years, the rainfall record for less than twenty years. Rainfall normals have been revised and now refer to the standard period 1921–50. Where observations are not available for the whole period, or where the site of the rain gauge has been changed, the normals are partly interpolated.

NOTES ON THE WEATHER FOR APRIL 1957

General: April was warmer than usual. Rainfall was comparatively low in the North Island but mainly adequate. Generally it proved to be a good month for stock and also favourable for pasture growth.

Rainfall: Rainfall was below normal over the North Island. Totals were less than half the usual value in Hawke’s Bay and in the Auckland Province except Northland.

Rainfall was doubled in many districts of the South Island from the Waitaki River northward. Total falls exceeded 20 in. in parts of the West Coast and also around Motueka. Bainham in northwest Nelson received nearly 34 in., while at the Moeraki River, inland from Haast in South Westland, 39 in. were recorded.

There was some unusually heavy rain over the Nelson Province from the 12th to the 17th in a northerly airstream, and totals for the six days amounted to as much as 19 in. in parts of the Motueka-Takaka area. Serious flooding occurred in the Motueka River and the Waimea Plains.

Temperatures: Temperatures were above normal, mainly by about two degrees. Departures were highest in western districts.

Sunshine: Sunshine was below normal by about an hour a day in Nelson, Westland, and Central Otago; and above normal by the same amount in parts of the Auckland Province.

Weather Sequence: An anticyclone which had moved on to the country towards the end of March persisted on 1 April, giving fine weather. During the next two days a deep depression passed far to the south, and the passage of the associated trough of low pressure brought rain to western districts as far north as Taranaki and also to Southland and Otago. On the 4th and 5th a weak trough affected eastern districts from Canterbury to Gisborne, but for the next three days the weather was again fine, under the influence of another anticyclone.

This anticyclone moved to the east of the North Island, and from the 9th to the 13th a deep depression passed far to the south-west, with the associated trough of low pressure later crossing the country. The weather was unsettled on the West Coast, and rain also extended at times to Nelson, the Marlborough Sounds, and parts of Taranaki. Rain continued in all these areas on the 14th with the development of a depression over the central Tasman Sea; by this time a strong northerly airstream covered New Zealand. The depression remained almost stationary for the next two days, and in the persistent northerly airstream rain extended to most districts, becoming heavy in Westland, Nelson, and Marlborough, with some serious flooding in the Motueka River and the Waimea Plains. On the 17th there were also substantial falls in many areas with the passage of the depression across central districts. With rising pressures on the following day the weather cleared over the South Island, but a shallow trough still affected the North Island.

From the 19th to the 21st a depression moved across the south Tasman Sea and the South Island, bringing some rain except in eastern districts of the North Island. On the following day the associated trough of low pressure became stationary and a depression formed in it over Northland, giving considerable rain. On the 23rd this depression moved past East Cape, while another trough affected the South Island; it was a day of general rain. There was a clearance in most districts on the following day as a ridge of high pressure extended on to the country from the north.

For the remaining six days of the month westerly conditions predominated, with an anticyclone to the north and low pressures to the south and south-west. The weather was unsettled on the West Coast, and rain also extended at times to Southland, Taranaki, and districts about Cook Strait. Elsewhere the weather was mainly fair, but some light rain affected Otago and Canterbury on the 25th.

M. A. F. BARNETT, Director.

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