East Coast Low Makes Way for Severe Thunderstorms, a December Scorcher, and Coral Sea Cyclone


The next week will bring a repeat of wild weather across many parts of Australia.

Severe thunderstorms will return to eastern states this weekend, followed by an outback heatwave from Monday, then a possible Coral Sea cyclone next weekend along with another major rain and storm event for south-east states.

The stormy start to summer follows a surprisingly wet November which culminated in an East Coast Low and defied seasonal forecasts, and the historical trend of below average rain during El Niño events.

The wet month resulted in spring totals near average for much of Australia, even after an exceptionally dry September and October.

The rain ahead during the coming week is a continuation of the November pattern — tropical moisture is feeding south across Australia due to high pressure systems remaining well away from the mainland.

With so much weather around let’s break down the week, system by system.

Thunderstorms for eastern Australia

A stormy start to summer is on the cards for eastern Australia this weekend.

Friday launched the season with a line of thunderstorms across inland Queensland, including a few dangerous supercell storms over the Channel Country, along with further rain in Victoria and south-east NSW

The storm threat today continues for much of eastern Queensland, while thunderstorms also redevelop across much of NSW and eastern Victoria, with severe storms possible from Sydney to Gippsland Victoria which could produce heavy rain, hail and gusty winds.

Severe thunderstorm thresholds could also be met in a band of Queensland from about the Sunshine Coast to the central inland.

While Melbourne is unlikely to see lightning, soaking rain could drop up to around 20 millimetres as a cold tongue of air advances east over south-east states.

Further rain areas and storms will develop on Sunday for the eastern seaboard, although the activity should split into two regions; one north of Brisbane, and the other south of Sydney and east of Melbourne.

Severe thunderstorms are likely over central Queensland on Sunday, including around Bundaberg, Gladstone, Rockhampton and Mackay.

Run of 40C days 

While eastern states spent the last month under umbrellas, much of Western Australia was sweltering through the hottest November on record.

Perth’s average maximums exceeded 30 degrees Celsius in November for the first time since the weather station opened in 1897.

The heat across the west is slowly creeping east and from Monday to Friday much of the outback will endure a run of days well above 40C.

The prolonged heat will exceed the Bureau of Meteorology’s heatwave thresholds for much of the interior this coming week, stretching from Broome to inland NSW.

A brief northerly airstream will carry the outback heat to the southern coastline on Monday sending Adelaide to 34C and Melbourne to 31C.

A second burst of hot northerly winds should follow around Thursday and Friday for south-east Australia, although for coastal regions the short duration of above average temperatures is below heatwave requirements.

A Coral Sea cyclone event?

Following the early summer heat, modelling is currently indicating the south-east can expect another round of rain and storms next weekend.

While its early days from a forecasting viewpoint, the predicted pattern has turned up on numerous models and has similarities to the past week, leading to a higher probability of a rain event compared to normal.

So what could this next event look like?

The general consensus is another low-pressure system will form, and under that scenario severe storms and flooding rains are likely to return, although a week out is pushing the boundaries of forecast accuracy and its too far ahead to make precise predictions on totals in any one region.

What’s perhaps even more surprising is models are forecasting a tropical cyclone will form in the Coral Sea next week, a rare occurrence during El Niño to have a system this early in the season.

And while climatologically Coral Sea lows track south-east away from Australia, this one actually has the potential to move towards the coast, although the forecast track is well beyond the usual temporal limit of predictability.

The presence of a Coral Sea cyclone in December is another intriguing sign this year’s weather is not quite playing by the rules.

Source: News