Figs. 137, 138, and 139.
East Coast Cyclone of Antarctic Origin.—The appearance on the coast of New South Wales of a cyclone owing its origin to the passage of an Antarctic disturbance is a somewhat irregular phenomenon, being of comparatively frequent occurrence in some years, or groups of years, and rare in others.[1] The case here shown is a fairly typical one. On the 26th September, 1908, an ordinary Antarctic "Λ" depression lay over the Bight, while a high pressure system covered the eastern half of the continent. By the 28th, the low had passed Gabo and extended well up the New South Wales coast-line, the southerly winds in rear of it being very cold, with showers and squally weather. By the 30th, the Antarctic disturbance proper had passed completely away, but an elliptical depression was left over Tasman Sea, the coastal weather being still dominated by southerly winds, and very cold and wet. Snow fell extensively over the mountains in New South Wales. Next day the circulation was definitely cyclonic, and the weather warmer owing probably to all southern connexion being severed by high pressures forming to southward over Tasman Sea. The storm centre then moved off in a south-easterly direction.
Figs. 140 and 141.
East Coast Cyclone of Inland Origin.—A typical example of this happened on the 18th January, 1911. On the previous day a very pronounced monsoonal trough extended from Western Queensland into Victoria, the line of lowest pressures being slightly below 29.8 inches. Moderate to heavy rain fell during the next 24 hours in front of this line, and on the 18th, the eastward advance of the trough carried it over the New South Wales coastline, where pressures promptly fell some two-tenths of an inch and the air circulation became of the cyclonic type. The fall in temperature along the New South Wales coast produced by its rear circulation was very slight.
- ↑ The fact that East coast cyclonic storms of antarctic origin are, for long periods, rare, helps to emphasize the very abnormal character of the weather of the latter half of 1905, in which no less than eight of these storms occurred. This is one of the many instances of definite tendency for special weather types to recur in certain seasons, thus giving to at least some seasons a kind of individuality. As the latter half of 1905 was, in Melbourne, the coldest on record, two abnormalities at any rate are in agreement.
