Weather Australia: BoM declare La Nina summer bringing weeks of rain, cold and risk of cyclones

The chances of Australia experiencing the soaking wet La Niña weather phenomenon again this summer have tripled, but at least this coming weekend should bring some sunshine.

Experts at the Bureau of Meteorology issued a La Niña alert from November onwards, most likely meaning heavier than usual rainfall for Australia’s eastern states throughout spring and summer.

While the east coast will continue to cop a drenching mid-week, with storms occurring, the weather should brighten in Brisbane, Sydney, Melbourne and Canberra during the weekend.

Brisbane will see the best weather on Australia’s east coast this week, with a sunny weekend and temperatures reaching 30. But forecasters warn wet La Niña conditions could be just around the corner (pictured, beachgoers on the Gold Coast)

Sydney's wettest day this week will be Thursday, particularly in the afternoon, with the chance of a severe thunderstorm. But the NSW capital could see sunshine both Saturday and Sunday (pictured, Sydneysiders brace the rain for a night out on Monday)

Sydney’s wettest day this week will be Thursday, particularly in the afternoon, with the chance of a severe thunderstorm. But the NSW capital could see sunshine both Saturday and Sunday (pictured, Sydneysiders brace the rain for a night out on Monday)

Brisbane is likely to cop a soaking on Thursday and Friday but recover in time for a weekend of sunshine and warm temperatures both days.

Sunday should reach 30C in the Queensland capital.

Sydney’s wettest day this week will be Thursday, particularly in the afternoon, with a strong chance of a severe thunderstorm.

There should be sunny periods both days at the weekend with temperatures in the mid-to-low 20s.

Frequent rainfall is expected across spring and summer this year (pictured) with swathes of Australia's east forecast to far exceed their usual levels

Frequent rainfall is expected across spring and summer this year (pictured) with swathes of Australia’s east forecast to far exceed their usual levels

It looks set to a cooler, wetter summer on Australia's east coast this year (pictured, a Sydneysider caught in a downpour)

It looks set to a cooler, wetter summer on Australia’s east coast this year (pictured, a Sydneysider caught in a downpour)

Canberra will see some grim weather mid-week, with rain and temperatures getting as low as 5C on Wednesday and Friday, with heavy rain on Thursday, but the capital could see a sunny Sunday.

Melbourne will cop the worst weather in the major capitals this week, with a very high chance of rain until Saturday and wintry temperatures.

Friday looks the wettest day for the Victorian capital, with thunderstorms also possible but luckily Melbourne could also see some sunshine on Sunday.

Meanwhile in the west, Perth looks set for warm sunny weather from Thursday to Saturday.

This is about as good as it's going to get in Melbourne this week - with cold temperatures and rain forecast all week (pictured, a cyclist at Albert Park Lake in Melbourne)

This is about as good as it’s going to get in Melbourne this week – with cold temperatures and rain forecast all week (pictured, a cyclist at Albert Park Lake in Melbourne)

FIVE DAY WEATHER IN YOUR CITY

SYDNEY

WEDNESDAY: Min 13. Max 20. Showers.

THURSDAY: Min 15. Max 24. Showers, possible storm.

FRIDAY: Min 13. Max 24. Shower or two.

SATURDAY: Min 12. Max 23. Mostly sunny.

SUNDAY: Min . Max 23. Sunny.

BRISBANE

WEDNESDAY: Min 16. Max 24. Shower or two.

THURSDAY: Min 17. Max 25. Showers, possible storm.

FRIDAY: Min 19. Max 29. Showers easing.

SATURDAY: Min 14. Max 28. Sunny.

SUNDAY: Min 14. Max 30. Sunny.

ADELAIDE

WEDNESDAY: Min 10. Max 17. Showers.

THURSDAY: Min 8. Max 17. Showers.

FRIDAY: Min 9. Max 18. Showers easing.

SATURDAY: Min 10. Max 17. Possible shower.

SUNDAY: Min 7. Max 20. Partly cloudy.

CANBERRA

WEDNESDAY: Min 5. Max 16. Shower or two.

THURSDAY: Min 9. Max 18. Showers, possible storm

FRIDAY: Min 5. Max 14. Showers.

SATURDAY: Min 5. Max 15. Shower or two.

SUNDAY: Min 3. Max 18. Mostly sunny.

MELBOURNE

WEDNESDAY: Min 12. Max 21. Rain developing, possible storm.

THURSDAY: Min 9. Max 18 Showers.

FRIDAY: Min 10. Max 16. Showers.

SATURDAY: Min 10. Max 15. Showers.

SUNDAY; Min 9. Max 17. Shower or two.

PERTH

WEDNESDAY: Min 7. Max 22. Mostly sunny.

THURSDAY: Min 9. Max 32. Mostly sunny.

FRIDAY: Min 13. Max 31. Mostly sunny.

SATURDAY: Min 15. Max 26. Mostly sunny.

SUNDAY: Min 13. Max 23. Partly cloudy.

HOBART

WEDNESDAY: Min 7. Max 18. Cloudy.

THURSDAY: Min 10. Max 16. Rain.

FRIDAY: Min 12. Max 19. Rain.

SATURDAY: Min 10. Max 15. Showers.

SUNDAY: Min 8. Max 16. Shower or two.

DARWIN

WEDNESDAY: Min 26. Max 34. Partly cloudy.

THURSDAY: Min 26. Max 34. Shower or two.

FRIDAY: Min 26. Max 34. Shower or two.

SATURDAY: Min 26. Max 34. Shower or two.

SUNDAY: Min 26. Max 33. Shower or two.

Source: Bureau of Meteorology

The key weather modelling assessed by the BoM had led to the weather office declaring an unusual La Niña alert, with the likely patterns set to arrive within weeks.

‘Historically, when La Niña alert criteria have been met, La Niña has subsequently developed around 70 per cent of the time,’ the BoM announced.

‘A 70 per cent chance of an event is approximately triple the normal likelihood.’

It is however not expected to be a severe La Niña pattern and could even be weak to moderate.

La Nina could mean an increased risk of flooding again for the east coast this summer (pictured, floods at Wingham, NSW in March 2021)

La Nina could mean an increased risk of flooding again for the east coast this summer (pictured, floods at Wingham, NSW in March 2021)

How La Niña typically works: Strong trade winds draw cooler water from ocean depths and warm surface waters north of Australia, leading to rainfall

How La Niña typically works: Strong trade winds draw cooler water from ocean depths and warm surface waters north of Australia, leading to rainfall

La Niña is caused by cooling of the ocean surface, or below-average sea surface temperatures, in the central and eastern tropical Pacific Ocean.

It leads to wetter weather from Indonesia down to Australia’s north and east coast.

As well as rainfall up to 20 per cent more rain than average for the eastern states, La Niña has many other features and impacts.

It also typically brings increased chances of flooding, cooler daytime temperatures and an increased risk of tropical cyclones in the eastern states and northern Australia.

Positives from a La Niña season may be a reduced chance of catastrophic bushfires and some relief from the soaring temperatures Australia seems to increasingly endure.

Other La Niña patterns can include slightly warmer night-time temperatures, especially further north and decreased frosts.

Australia saw La Niña conditions from last summer into autumn, with December 2020 the third wettest since national records began in 1900.

What is La Niña? And how will it affect Australia

What is it? A cooling of the ocean surface, or below-average sea surface temperatures, in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to increase while rainfall decreases over the central tropical Pacific Ocean. The normal easterly winds along the equator become even stronger.

How much more rain will we get? In eastern Australia, the average December-March rainfall during La Niña years is 20 per cent higher than the long-term average, with eight of the ten wettest such periods occurring during La Niña years.

Increased chance of flooding: The east coast of Australia tends to be less affected by La Niña during the winter months but can experience severe flooding during La Niña summers.

Cooler temperatures: La Niña years tend to see cooler than average maximum temperatures across most of mainland Australia south of the tropics, particularly during the second half of the year. This is due to increased cloud cover and rainfall. Increased cloud cover however acts as an insulator and results in warmer than average minimum temperatures.

Get link

xoonews.com