Showing all posts about climate
Parts of Australia may see heatwaves before the spring equinox
11 September 2023
The ten-day weather forecast for some parts of NSW are currently predicting several days with maximum temperatures in the vicinity of thirty degrees centigrade. This, at the moment, for Saturday and Sunday, 16 and 17 September, and Tuesday 19 September. These temperature ranges come close to the official definition of a heatwave:
A heatwave occurs when the maximum and the minimum temperatures are unusually hot over a three-day period in a specific location. This is considered in relation to the local climate and past weather at that place.
Such a forecast may not be entirely surprising if not for the fact Australia is only into the first few weeks of spring. Technically though, were the spring equinox — which falls on Saturday 23 September this year — to be observed as the beginning of spring (as is the case in parts of the world), then it would still be winter in Australia. A heatwave in winter, fancy that.
Long range forecasts are not always accurate though, and conditions may change between now and the weekend. Still, such warm temperatures in the middle of September are alarming to say the least.
And for anyone wondering, each season in Australia commence on the first days of March, June, September, and December, because Australia adheres to the meteorological seasonal system. Many northern hemisphere nations however observe the astronomical season convention, meaning seasons change on about the beginning of the third week in March, June, September, and December.
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Australia, climate, environment, weather
Tropical cyclones may return to Sydney coastal region
24 November 2022
For about thirty years, until the mid-seventies, tropical cyclones were relatively regular weather events in the Sydney region, but now meteorologists are concerned they may return. But climate change is not behind their possible re-emergence, rather changes in the Interdecadal Pacific Oscillation (IPO):
The inordinate frequency of cyclones from the 40s to the 70s and the disappearance in recent decades is not random variability. A 2020 report in the Journal of Southern Hemisphere Earth Systems links NSW cyclone activity with changes in the Interdecadal Pacific Oscillation (IPO). The current state of the IPO and other cyclone influences has rapidly shifted in the past three years to resemble the 1950s. Meaning, the current phase of the Pacific is conducive to tropical cyclones impacting NSW.
While more often see in northern regions of Australia, tropical cyclones haven’t reached Sydney in decades, but they have impacted some parts of NSW, bringing flooding and storm damage with them.
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A spring of Sam (Southern Annular Mode) and La Nina summer?
5 September 2022
Image courtesy of disassociated.
While there’s a slim chance regions of Australia may yet be spared a third consecutive wet, rainy, La Niña weather event this summer, the outlook for spring is not so promising.
The Bureau of Meteorology advised last week parts of eastern Australian can expect higher than usual rainfalls, thanks to another meteorological phenomenon, a positive Southern Annular Mode, or SAM, for short:
Further, Dr Bettio said a positive Southern Annular Mode (SAM) is also likely, which pushes weather systems south, bringing wetter easterly winds to NSW and fewer cold fronts to western Tasmania. Dr Bettio said parts of Western Australia and western Tasmania are likely to experience below average rainfall this spring. Almost all of Australia is likely to experience warmer than average nights, while cooler days are likely for large parts of the mainland except the tropical north.
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Australia on alert for a third La Nina event this summer
18 August 2022
Another wet summer may be on the cards for parts of Australia, after the Bureau of Meteorology moved the ENSO Outlook to a La Niña alert status.
This status change follows a renewal of cooling in the tropical Pacific Ocean towards La Niña thresholds over recent weeks, as well as the persistence of the Southern Oscillation Index (SOI) at La Niña levels and strengthened trade winds at La Niña levels. Climate models indicate further cooling is likely, with four of seven models suggesting La Ni Niña a could return by early-to-mid southern hemisphere spring.
If another La Niña eventuates this summer, it will be the third in a row.
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Forty four degrees Celsius, I think that is a record for Sydney
1 January 2006
It’s almost midnight in Sydney. I think it’s safe to go outside now. Earlier today temperatures hit 44° Celsius. The last time I was in place that hot was Aswan, in Egypt.
44°C. That must be an all-time record for Sydney.
In other news, I’m pleased to report last night’s festivities were indeed festive. Seems quite a party was had at my apartment building too. When I arrived home today someone had ripped a fire extinguisher off the wall and sprayed most the common areas with it.
There’s fine white powder all over the stairs and on the roof top area.
Other than that I spent the day tinkering with disassociated, and slipping cool, cool beverages. Too hot for anything else, trust me. Happy New Year 🙂
Originally published Sunday, 1 January 2006.
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