Page:Hunt - The climate and weather of Australia - 1913.djvu/154

Rh. 137, 138, 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. 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.

. 140 141.

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.