Black nor'easter

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Sydney CBD

A black nor'easter is a persistent and potentially violent north-easterly

southern New South Wales, usually between late spring and early autumn, about two days a year (or more, depending on the intensity).[1]

Developing offshore as a deep coastal trough, the storm is heralded by the rapid build-up of dense black cloud that brings heavy

low.[1] The storm system may cool down warm days due to the persistent blanket of thick moisture-rich clouds.[2]

Although not

cut off low from the Southern Ocean. Black nor'easters were first recorded during the 19th century and were so-named because the affiliated darkness (of the moisture-loaded clouds) can transform the day to as dark as twilight.[3]

Background

Dark clouds forming before the storm in Darling Harbour

The cause of a black nor'easter is the gathering of moist cooler air from the south and the tropical humid flow from the north, where north easterly winds aggregate with the moisture, thereby creating dark, rain-filled clouds.

Sydney Morning Herald on 30 October 1911, where it described a black nor'easter in southern New South Wales:[5][6]

Conditions were undergoing a change, which portended unsettled, thundery weather with rain in scattered parts of the State. Yesterday afternoon a black nor'-easter raged, the wind attaining a mean average velocity of 26 miles.

Northeasterly

thunderstorms, dramatic rainfall and at times hail.[7]

Unlike an

East coast low (ECL), which tends to occur in the cool months, a black nor'easter occurs in the warm months and originates from the northeast, although a black nor'easter can turn into an east coast low as it heads south, such as in the case of the 2022 Eastern Australia flood event.[8][9] Also unlike ECL's, black nor'easters can heavily affect inland areas of New South Wales and Queensland.[1]

Formation

The virtually black clouds associated with the storm over Darlinghurst

Black nor'easters are generally

sea temperatures on the East Australian Current (EAC).[10]

Forecaster Craig Brokensha, describes a black nor'easter; "an unstable low pressure trough drifting from inland Australia, moisture feeding into another trough sitting adjacent the East Coast, with the two predicted to combine."[5] They can also be formed by a cool pool of air that arrive from the Great Australian Bight, whereby spurring a low-pressure system over the southeast simultaneously as a moisture-rich coastal trough (fueled by warm sea temperature) – This can cause higher evaporation, thereby raising the amount of liquid in the atmosphere. When this moisture is brought south by moist northeasterly winds and chilled by the cooler air in the upper-level low higher up, it condenses and falls as rain.[11]

Referred as an

east coast low, they bring forth the most intense storm wave environment.[5]

Incidents

Due to the strong winds caused by the Black Nor'easterly storms, a number of people in

power lines (where thousands of homes and businesses would be left without electricity) and collapse roofs.[8]

Notable storms

Black nor'easter clouds over southeast Australia (March 2021)
  • On
    blocking high in the Tasman Sea that directed a strong, moist, low pressure trough towards the NSW coast.[31]
  • In late February and early March 2022, a black nor'easter persisted for nearly two weeks where it ravaged the southeast coast of Australia, flooding areas of major cities such as Brisbane, Lismore and as well as western Sydney, among other cities. Although the nor'easter turned into an east coast low as it moved south.[32]
  • The July 2022 floods were caused by a black nor'easter due to tropical moisture that arrived from northern Australia which interacted with a low pressure trough on the New South Wales coast and later became an east coast low.[10]
  • Between 4 and 6 April 2024, a black nor'easter dumped heavy rain in southern Queensland and New South Wales, killing one man in
    Western Sydney.[33][34] At 167mm, Penrith recorded its heaviest rainfall on record. Over 100mm fell in areas in southern Queensland and the NSW Northern Rivers on the 4th, causing floods.[35]

See also

References

  1. ^ a b c Black nor'easter to soak Sydney and surrounds by Ben Domensino from Weatherzone. 4 April 2024. Retrieved 5 April 2024.
  2. Illawarra Daily Mercury
    . Wollongong, NSW: National Library of Australia. 8 January 1951. p. 10. Retrieved 27 March 2015.
  3. ^ "BLACK NOR-EASTER". The Sydney Morning Herald. National Library of Australia. 30 October 1911. p. 7. Retrieved 27 March 2015.
  4. ^ Month's worth of rain could fall in one day in east coast black nor'easter. by Benedict Brook from News.com.au. 5 April 2024.
  5. ^ a b c "From the beating heart of a Black Nor'Easter | Swellnet Dispatch". Swellnet. Retrieved 12 November 2018.
  6. ^ 30 Oct 1911 - BLACK NOR-EASTER by Trove. Retrieved 3 April 2024.
  7. ^ 'Black nor-easter' brings rain, storms to NSW, SEQ by The New Daily. 3 April 2024.
  8. ^
    ABC News Australia
    . Tuesday, 19 July 2016
  9. ^ BOM warns of more wet weather, dangerous conditions as east coast low looms off NSW By Kate Doyle, ABC Weather. 2 March 2022.
  10. ^ a b East Coast soaking on Friday by Joel Pippard from Weatherzone. 3 April 2024.
  11. ^ Explained: What is causing the 'Black Nor'Easter' smashing Sydney? by Angus Thomson and Christopher Harris from The Sydney Morning Herald. 5 April 2024.
  12. ^ Man killed by falling tree in Federal as wild weather lashes northern NSW by By Donna Harper – ABC News
  13. ^ Sydney storm: Man killed after tree falls on moving car by BBC News
  14. ^ Man dies when tree falls on moving car in Sydney during wild storm by The Guardian
  15. ^ "Storm drenches Sydney". UPI.com. 12 February 2010. Retrieved 1 June 2010.
  16. ^ "Sydney dries out but regional threatened". News.smh.com.au. 12 February 2010. Retrieved 1 June 2010.
  17. ^ "Weather News - Wild storms lash Sydney". Weatherzone.com.au. 13 February 2010. Archived from the original on 16 February 2010. Retrieved 1 June 2010.
  18. ^ "Rain swamps Sydney's water catchments". Smh.com.au. 7 February 2010. Retrieved 1 June 2010.
  19. ^ Huffer, Julie (10 February 2010). "Heaviest rain in almost 20 years - Environment - News | Hornsby & Upper North Shore Advocate". Hornsby-advocate.whereilive.com.au. Archived from the original on 20 January 2013. Retrieved 1 June 2010.
  20. ^ a b "Roof collapses at movie theatre at Westfield Hornsby". 18 November 2013.
  21. ^ Clean-up continues after tornado strikes at Hornsby in Sydney's north
  22. ^ "Hornsby was hit by a tornado, Bureau of Meteorology confirms". The Sydney Morning Herald.
  23. ^ Rain: Warragamba Dam gets huge boost as chaos reigns in wake of weekend deluge in NSW, Queensland by The Australian, 10 February 2020
  24. ^ Sydney rains: Record rainfall brings flooding but puts out mega-blaze by the BBC News, 10 February 2020
  25. ^ Thousands Without Power As NSW Cops Heaviest Rain In Two Decades by 10 daily, 9 February 2020
  26. 7 News
    , 9 February 2020
  27. ^ NSW weather: residents evacuated from flooded areas and thousands left without power by Calla Wahlquist and Australian Associated Press from The Guardian. 9 Feb 2020
  28. ^ NSW weather: mini-tornado damages homes in Chester Hill, says NSW Premier Gladys Berejiklian by ABC News. 20 March 2021
  29. ^ House floats down river in Wingham as dangerous weather system leaves a path of destruction by ABC News. 20 March 2021
  30. ^ Record rains, flooding prompt evacuations in Australia Archived 2021-03-25 at the Wayback Machine by Yahoo! News
  31. ^ Widespread rain to fall in all states as two storms form in Australia's east and west by Ben Deacon from ABC News. 20 March 2021
  32. ^ "Savage weather batters south-east Queensland with deadly flash flooding escalating". The Guardian. 25 February 2022. Archived from the original on 27 February 2022. Retrieved 27 February 2022.
  33. ^ Man found dead in Queensland floods as black nor'easter weather system hits eastern Australia Luca Ittimani with Australian Associated Press. The Guardian. 4 April 2024. Retrieved 6 April 2024.
  34. ^ Evacuation and extreme weather warnings issued after heavy rain falls across parts of Sydney and the Illawarra by ABC meteorologist Tom Saunders, Brooke Chandler and Jesse Hyland. ABC News. 6 April 2024.
  35. ^ Evacuation and extreme weather warnings issued after heavy rain falls across parts of Sydney and the Illawarra by ABC meteorologist Tom Saunders, Brooke Chandler and Jesse Hyland. ABC News. 6 April 2024.