The first thunderstorm event of the season is set to descend on the east coast in the coming days.
The La Niña is making its presence felt with moisture streaming in from the Coral Sea — as that moisture collides with instability over central Australia, it is forecast to trigger widespread thunderstorms over the eastern half of the continent late this week.
Flash flooding, damaging winds and hail are all on the cards, so now is the time to take care of the gutter clearing and yard tidying that you’ve been putting off.
According to Bureau of Meteorology forecaster Jonathan How, we could see rainfall over all states and territories over the next few days, but the focus is going to be on Queensland and northern New South Wales.
On Wednesday, southern inland Queensland and northern New South Wales should expect showers and potentially severe thunderstorms.
But Thursday is when things are expected to really ramp up, when a low pressure system currently over Western Australia moves east, firing up storms across parts of South Australia and the Northern Territory.
Friday is looking like it will be the biggest day.
“We’re going to see very widespread thunderstorms all the way from the Top End down through western Queensland, eastern South Australia, western New South Wales, into Victoria as well,” Mr How said.
Things are expected to contract by Saturday, but wild weather is still expected around north-east Victoria, eastern New South Wales and, importantly for the footy, eastern Queensland.
What about the grand finals?
Brisbane has a chance of a shower, most likely in the afternoon and evening, on AFL grand final day.
There is a chance of a thunderstorm in the evening, and the humidity is still expected to be up during the game, but the BOM currently believes any storms are looking more likely to arrive inland.
Meanwhile, following a possible storm on Saturday, Sydney on Sunday for NRL grand final day is forecast to be cloudy with showers and the chance of a thunderstorm during the morning.
How much rain?
Widespread falls of 30 to 50 millimetres are expected across eastern Queensland, eastern New South Wales and northern Victoria.
With the hit-and-miss nature of thunderstorms, the biggest uncertainty at the moment is who will get hit with the most intense rainfall.
“We could see three- to four-day totals for about 100 to 150mm; the tricky part is actually picking where that is going to be,” Mr How said.
But he said places in eastern New South Wales and eastern Queensland could see those big totals.
Despite the low forming in the west, Western Australia is missing out on this patch of rain and storms — there is a medium chance of a shower on Monday as the next batch of weather rolls through.
Severe storm trifecta
For those regions that have had plenty of rain this year, more falls could cause trouble.
“There is concern that some catchments are really quite saturated, particularly across northern Victoria, and so we could see some river rises,” Mr How said.
Flash flooding, severe winds and hail are also on the cards.
Mr How said conditions were good for large hail, with possible hail Wednesday for inland Queensland and New South Wales, but Friday and Saturday were going to have the most instability in which the large hail could grow.
“We could potentially see some giant hail around and damaging winds is also a risk.
Relief for south-east Queensland
While the southern states have been getting some relief after the big dry, despite much optimism and speculation around what the La Niña might bring, south-east Queensland has largely missed out — so far.
“This is looking like the best chance of rainfall, even east of the divide, so places around Brisbane, the Gold Coast and the Sunshine Coast who haven’t seen much rainfall,” Mr How said.
The current forecast for Brisbane suggests Friday and Saturday will be partly cloudy, with a medium chance of showers for the city from Sunday.