Thank you for all your replies.
Princess Anna, we're about to have a relatively early Easter this year, so early that the first school term of the year has been extended to later in April. Normally school holidays are calculated to include public holidays so that there is less disruption all round. Easter Sunday is calculated as the Sunday after the first full moon after the spring equinox or autumn equinox down here. The full moon is today. Perhaps that also explains why this is a particularly odd year weatherwise.
Another explanation is that we had a particularly severe El Niño effect in 2009 to early 2010, with relatively cool years from March 2010 and 2011, due to one of the strongest La Niña effects on record. As a rule of thumb, we get dry conditions in an El Niño, and wet conditions in a La Niña, with Peru, Bolivia and Chile getting the opposite of whatever we get. But that isn't the full picture, according to our
Bureau of Meteorology. Apparently there is another factor in the Indian Ocean called the IOD or the Indian Ocean Dipole. But I'm not sure how the IOD affects the weather on Australia as a whole. At the moment, on the Pacific side, we are in a
neutral phase, neither La Niña nor El Niño.
And I'm even less clear what happens in the Northern Hemisphere, and how these ocean currents and conditions might explain your good years and bad years to some degree. I don't understand what the picture is in the Northern Hemisphere so well, let alone what happens with the Atlantic Ocean.
stargazer wrote:There's such a spread in latitude in North America (tropics to Arctic) that it'd be hard to give an answer - not to mention terrain-induced effects such as mountain snow or lake-effect snow (I imagine the same is true in Australia, which is similar in size to the US).
Yes, Australia is similar in width to USA, not counting Alaska and Hawaii. But South America covers an even wider spread of latitudes than does North America. South America stretches from about 12 degrees North to something like 55 degrees South of the Equator, quite near the Antarctic Circle. Whereas Australia only stretches from 10 degrees South to about 45 degrees South. Even the southern tip of New Zealand is less than 50 degrees South.
The longest and biggest range of mountains here is the Great Dividing Range which stretches from Cape Yorke Peninsula to Southern Victoria where it swings around towards South Australia, where we have the Mount Lofty and Flinders Ranges. We don't have anything like the Rocky Mountains in North America, or its South American continuation, the Andes mountains.
Though we get the occasional snow storm during a cold snap along the Great Dividing Range from Victoria to Southern Queensland, we don't have completely snowy winters even there, except in the Snowy Mountains, and the Australian Alps, near Mt Kosciuzko. That is to say, in Southern NSW and Northern Victoria. Even Canberra or Hobart, in Southern Tasmania, are seldom snowed under with actual snow. This is why the weather here isn't simply a mirror reverse of what happens North, though it may seem like it at times.