New South Wales, Australia - rainfall records tumble

Yearly rainfall records in the Australian state of New South Wales (NSW) for many cities and towns were broken back in October or even earlier, and we still have December to go yet.

Sydney, NSW broke its 165 year old rainfall record back in October. As at the 30th November 2022 Sydney is sitting at 2451.8mm, or 96.5 inches. I may not get to 100 inches as a drier pattern has developed over past 3-4 weeks.

The nearest official gauge to my home around 100kms (60 miles) south of Sydney is at 2537.6mm, or 99.9 inches and will probably get 100inches by end of year. Yearly average for that gauge prior to this year is around 1000mm, or 40 inches, but that is skewed by a short 20 year history and severe drought in 2018-19. A more exposed gauge just 15kms down the coast at Kiama has recorded 2803.8, or 110 inches YTD. My area is backed by a 500-800m (1650-2650 feet) escarpment that is only a few miles inland and falls of well over 130 inches have occurred YTD. Only a few coastal range gauges in the NE of state have beaten that, such as Mount Seaview with 140 inches.

Inland totals have been much lower, but still with records tumbling and many towns recording double their normal average River flooding and flash flooding have been major problems with whole towns isolated. Some lives have been lost. Wheat and cereal crops on all but hilly ground are gone.

What has caused this? Three weather patterns have combined to create this years rain records. La Nina, which I hardly need to explain. Indian Ocean Dipole, which has been negative – this means warmer water offshore NW Australia, moisture is picked up by jet streams and triggered by frontal and low pressure events over SE Australia. Lastly the Southern Annular Mode was positive through much of Autumn and Winter. When positive the Southern Annular Mode sees the consistent belt of westerly winds that normally sit around 40’ south being pushed further poleward. This allows more episodes of humid E and NE winds across New South Wales. I live in a town notorious for its ‘August Winds’ where west winds often exceed 100kph (60Mph), but this year people have asked where are the August Winds?

From a storm chasing perspective. Basically a disaster! Our storm season would in a great year not even come close to the mid west USA poorest ever year. However in a normal year we still would see a few non-tornadic supercells, large hail and lots of lightning. This season (and last) it has been rain, rain and more rain. What major thunderstorm events that have occurred have often been in the far west of the state in normally arid lands where finally there has been some dry lines. Ten to twelve hour drives (one way), poor roads, flooding and sheer isolation (getting stuck in the middle of nowhere is a real prospect) hamper any attempts to chase.

Below is a video of one of my chase attempts gone wrong. There was a very slim hope of a tornado this day as shear was close to respectable USA, but the whole system quickly became a training thundery rain mess with deadly flash flooding – later that night about 60 miles north of where I was a whole town (Eugowra) was evacuated as flash flooding tore through the entire town. Sadly lives were lost.

 
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