Technical An example of when a storm was able to form in eastern Sydney basin.

Joshua Randazzo

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2012 hailstorm.png
 

Steve777

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Other examples of severe storms that hit Eastern Sydney would be the April 1999 Sydney Hailstorm, the Kurnell Tornado (16/12/2015) and a severe storm early on 28/11/2018 that dumped 120 mm over the CBD and inner suburbs in a couple of hours: https://watchers.news/2018/11/28/sydney-storm-november-28-2018/. All extensively discussed in the old WZ forums at the time.

Not scientific but just my impressions:
  • The severest storms over Sydney do seem to develop locally. On the radar it often looks like they're oozing out of the ground in the Sydney Basin then moving on, normally Eastwards.
  • Sometimes they develop over the sea and impact the coast, most commonly in early Winter. I recall that there was what the press called a ‘mini tornado’ that hit Bronte several years ago: https://www.sbs.com.au/news/flash-flooding-tornado-hit-sydney
  • Storms that develop over the Central Tablelands tend to fall apart as they enter the Sydney Basin. They seem to get closer to the coastline in the Illawarra and the Central Coast, I surmise because there’s higher ground (300-500 m) closer to the coast.
  • Also, Southerlies and sea breezes interpose a layer of cool, stable air between the ground and any convection, killing off many storm cells.
 

Joshua Randazzo

Early Days
Jan 1, 2021
82
81
18
near sydney CBD.
Other examples of severe storms that hit Eastern Sydney would be the April 1999 Sydney Hailstorm, the Kurnell Tornado (16/12/2015) and a severe storm early on 28/11/2018 that dumped 120 mm over the CBD and inner suburbs in a couple of hours: https://watchers.news/2018/11/28/sydney-storm-november-28-2018/. All extensively discussed in the old WZ forums at the time.

Not scientific but just my impressions:
  • The severest storms over Sydney do seem to develop locally. On the radar it often looks like they're oozing out of the ground in the Sydney Basin then moving on, normally Eastwards.
  • Sometimes they develop over the sea and impact the coast, most commonly in early Winter. I recall that there was what the press called a ‘mini tornado’ that hit Bronte several years ago: https://www.sbs.com.au/news/flash-flooding-tornado-hit-sydney
  • Storms that develop over the Central Tablelands tend to fall apart as they enter the Sydney Basin. They seem to get closer to the coastline in the Illawarra and the Central Coast, I surmise because there’s higher ground (300-500 m) closer to the coast.
  • Also, Southerlies and sea breezes interpose a layer of cool, stable air between the ground and any convection, killing off many storm cells.
Its funny you say that about sea breeze killing storms i just have to bring this up again on new years day 1947 when the violent classic supercell hit sydneys east there was a fresh north east sea breeze.
 

Steve777

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Its funny you say that about sea breeze killing storms i just have to bring this up again on new years daey 1947 when the violent classic supercell hit sydneys east there was a fresh north east sea breeze.
Interesting. Yes, sea breezes and Southerlies don't always kill storms. In the right conditions, which I suppose would be enough convection happening above the cooler, stable air, a storm will sail right over the top, as apparently happened on New Years Day 1947. In any case I expect that if the storm is powerful enough, it might be harder to kill.

One thing that I've often noticed is how storms often 'jump over' the coast. They come off the Tablelands, fall apart or weaken into light rain as they pass over Sydney then regnerate out to sea.
 
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Joshua Randazzo

Early Days
Jan 1, 2021
82
81
18
near sydney CBD.
1947.png


As can been seen in the BOM report of the 1947 SUPERCELL. it was the sea breeze the caused it to form into supercell. north west sea breezes often enhances storms while the south west sea breezes often kills storms
 

Joshua Randazzo

Early Days
Jan 1, 2021
82
81
18
near sydney CBD.
Interesting. Yes, sea breezes and Southerlies don't always kill storms. In the right conditions, which I suppose would be enough convection happening above the cooler, stable air, a storm will sail right over the top, as apparently happened on New Years Day 1947. In any case I expect that if the storm is powerful enough, it might be harder to kill.

One thing that I've often noticed is how storms often 'jump over' the coast. They come off the Tablelands, fall apart or weaken into light rain as they pass over Sydney then regnerate out to sea.

I also must add that the 1947 supercell was at its strongest stage over the eastern beaches of sydney meaning that if the sea breeze didn't turn it into supercell the high humidity and temperatures must of done something.
 
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