1919.] Pemberton.—Weather Forecasting in New Zealand. 169 
place, and the weather again assumed a very boisterous character, heavy 
rain falling, accompanying thunderstorms in various localities. 
About Cook Strait particularly electrical disturbances were severe, and 
these were apparently the result of a secondary centre passing through the 
strait in the early hours of the morning of the 6th. On the weather map of 
the 6th the second depression was shown just eastward of the Dominion, 
and the winds were southerly, blowing with gale force over most of New 
Zealand, with cold and showery conditions. 
Relation of Westerly Area of Low Pressure to Adjacent Anticyclones. 
Fig. 6 is an isobaric chart showing the distribution of pressure over a 
much wider field, and includes the isobars as charted by the Commonwealth 
Weather Bureau and those of our own on the 5th June, 1913. It depicts 
the two typical forms of isobars discussed previously, and shows the 
position of the /\ or westerly low-pressure area in its relation to two 
adjacent anticyclones. New Zealand is crossed by an almost constant 
procession of such anticyclones and westerly “lows,” with other systems 
of less frequency which will be mentioned presently. 
Between the two “ highs ” to the northward will also be seen a wedge 
of relatively low pressure. This is the southern extension of a subtropical 
low-pressure system, and is in the region where originate many of the 
cyclones which affect New Zealand. 
Winter Cyclones. 
During the winter months the general high-pressure belt is in more 
northern latitudes, and there is a tendency for the centres of Antarctic 
cyclones to pass more frequently in the neighbourhood of the southern 
portion of New Zealand. Fig. 7 is an instance of this type, and the chart 
is an example of the benefit of the Macquarie Island wireless reports, with¬ 
out which, in this case, it would have been impossible to say definitely 
whether or not a centre was situated in the position where it is shown on 
the map. 
The barometer at Macquarie Island read 29-45 in., while that at the 
Bluff recorded 29-25 in. The wind at the former station was easterly, while 
at the latter it was north-westerly. These reports gave definite evidence 
that a centre lay between the two stations. The path of the centre was 
along the thick line. There were at least two centres in this system, the 
first being shown to the eastward. The second moved along almost the 
identical track taken by the one preceding, which succeeding “ lows ” have 
a habit of doing. Except when the centre actually passes over the South 
Island, the accompanying wind and weather in this class of storm are 
similar to that of a westerly low pressure, provided that the barometric 
gradient is about equal in both cases. 
The above disturbance might be referred to as a westerly cyclone, because 
the path is in a direction nearly due west to east, and the winds are mostly 
from some westerly direction over the major portion of New Zealand, the 
changes being from north-west to south-west. 
Cyclone with Double Centre. 
On the 9th August, 1913, the barometer ranged from about 29-70 in. 
to 29-90 in. over the whole Dominion, and the winds were only moderate 
