The east coast is set to be smashed by dangerous weather this weekend with several months worth of rain set to pour down in just hours.
Flooding is “essentially guaranteed” from this weekend as a 500km band of wild, unpredictable weather bears down on Australia’s east coast.
And right at the centre of the danger is Sydney and the Illawarra, which could be hit with a nasty East Coast Low as early as Saturday.
With up to 300mm of rain in the gauge, that would easily deliver more than month of rain in a single day.
And it’s not just New South Wales – Queensland, too, is looking distinctly soggy over the coming days.
An upper level trough is the cause of the weather drama, pushing cool air up from southern Australia.
That trough will interact with tropical moisture further north to produce these windy and wet intense weather systems.
“A trough is developing just off the NSW coast,” saidSky News Weather channel senior meteorologist Tom Saunders.
“We expect that trough will deepen over the weekend to a fully-fledged East Coast Low.
“These systems are notoriously difficult to forecast exactly when and where they’ll strike but at this stage, it looks like it’s that central part of the NSW coast with rain also impacting northern parts of the country,” he said.
Flash flooding ‘essentially guaranteed’
East Coast Lows have many of the characteristics of cyclones but aren’t classified as such, as they are in subtropical waters. But they can still bring immense amounts of rain, gales and coastal erosion.
“Flash flooding and river flooding is essentially guaranteed.,” Mr Saunders said of the impacts of this weekend’s weather.
“Damaging winds and power outages are possible particularly towards the back end of the weekend into early next week.”
So how much rain could come down? Well it depends on the meteorological model but 200-300mm is a possibility with a chance of up to 400mm in isolated areas and around Sydney, Wollongong and across the Blue Mountains. And that’s really not great.
“That’s covering the Hawkesbury Nepean catchment and that catchment is still quite wet and that would certainly be enough rain for major flooding,” he said.
If that happens, parts of Sydney’s western and northern fringes could be inundated.
The Bureau of Meteorology has issued a severe weather warning for heavy rainfall starting on Saturday, from around Ulladulla to Sydney.
NSW SES Commissioner Carlene York said because dams and rivers were already full, there was “significant” concern about what is to come for communities across the state.
“This significant rain event could have some major effects across communities from Port Stephens down to Batemans Bay so we’re preparing and getting community messaging out to let them know they’re in some of these areas of risk and to be ready.”
The Bureau is forecasting 60-90mm falling on Saturday in Sydney, 100-150mm on Sunday and up to another 80mm on Monday. Maximus should be around 17C.
It could be even heavier in Wollongong and the Blue Mountains with 150-200mm possible on Sunday alone.
Newcastle is looking at 35-50mm on Sunday and 50-80mm on Monday. Further north, there could be some showers over the weekend for places like Port Macquarie and Grafton but the totals will be far lower. Inland areas and southern NSW could also see rain but again it will be far less heavy than the Sydney basin.
Canberra is forecast to see between 10-25mm of rain between Saturday and Monday.
Queensland to be drenched
Widespread rain continues across Queensland. It will ease off on Saturday but should start bubbling up again on Sunday with the heaviest falls seen early in the week.
Across northern parts of the coast, rain totals of 100mm are on the cards.
Townsville will see some showers as the weekend progresses, but Monday is when it will chuck it down, with 40-60mm forecast, and more for Tuesday.
In Brisbane, Saturday is looking like the soggiest day, with up to 25mm of rain then lessening on Sunday. But Tuesday could again see downpours. The other capitals will have a very different weekend with Melbourne, Adelaide and Hobart all remaining dry and partly cloudy with almost uniform mid teen highs.
Darwin will see some blue skies with maximums of 29C. But it’s Perth that will be gloriously sunny. But it will be relatively mild with temperatures only just nudging 20C.
– with Ben Graham.