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Widespread rain in WA brings half of Perth's monthly average in one night and delivers record rain for agricultural areas

By Tyne Logan, Angus Mackintosh and James Liveris, Wednesday May 5, 2021 - 05:52 AEST

Widespread parts of Western Australia have endured a drenching overnight, with record-breaking rain totals recorded through some agricultural districts and more still to come.

The downpour was brought about by a thick band of cloud, stretching from the west Pilbara to the west Eucla, an area of land over 800,000 square kilometres ? the equivalent to the whole of New South Wales. 

While cold fronts are usually responsible for rain this time of year, Wednesday's rain was brought on by a mid-level trough, feeding in tropical moisture in from the north-west.

Perth surprised forecasters with a constant stream of rain from midnight totalling 46 millimetres, a figure the Bureau of Meteorology's Luke Huntington said was far more than expected.

"We were only expecting to get around 20 millimetres so we've actually doubled what we thought we're going to get," he said. 

The overnight drenching made up half of the monthly average for May in just one night.

'Best start to the season in years'

Throughout the agricultural region the rain fell even heavier.

Some of the highest rainfall totals included 86millimetres at Wooodperry Homestead, near Bridgetown, 81 millimetres in Kojonup in the Great Southern, 69 millimetres in Northam and an unseasonal 86 millimetres in Roebourne, in the Pilbara.

Record-breaking daily falls of 60 millimetres were recorded in the cropping town of Lake Grace in the Great Southern, doubling their previous daily record for May of 30.2 millimetres and inching close to the record rainfall total for the entire month of May at 66 millimetres.

Grain and sheep farmer Ross Chappel, who has lived in the Lake Grace region his whole life, said the rain had brought about the "best start [to the cropping season)]in years". 

"It's the first time in four years I've emptied 50 millimetres [out of the rain gauge]," he said.

"Dams are full, rainwater tanks full, it's great.

"We haven't seen that kind of thing for a long, long time."

Pingrup farmer Kelvin Holmes said it would bring to a halt four years worth of water carting.

"It's beautiful," he said. 

"The dams that haven't had any water ? they're now full.

"We got rid of 11,000 ewes over the last year because of the water."

The wet start to the season marks a stark contrast to recent years, which saw areas of the Great Southern in the grips of an unprecedented dry spell with millions of litres of water being trucked into a dozen towns declared by the State Government as water-deficient.

The rainfall was not just constrained to the south of the state, with the overnight downpour brining the Gascoyne's three-month totals up to more than 300 millimetres in some areas, with pastoralists confidently calling it the best start to a season in more than 20 years.

Martin Baston is from Jimba Jimba Station about 150km east of Carnarvon, and said the latest rainfall was the icing on the cake.

?This country is looking absolutely amazing,? Mr Baston said.

Mr Baston said past droughts in the Gascoyne had been unforgiving.

?The land out here can make you or break you,? Mr Baston said.

?But this consistent rain has really saved our bacon, and now we?ll get a winter herbage which gives the scrub time to grow back and puts you in a reliable situation.

More rain to come

Conditions are set to ease from the west coast today, as the trough moves east over the south west land division.

But the wet is not over yet. 

Mr Huntington said a second trough would approach the west coast on Thursday, bringing even more rain.

"There could be another five to 15 millimetres associated with that," he said.

"But if you do get under a thunderstorm, you could even see falls up to another 20 millimetres close to that west coast."

He said with the cloud and thunderstorms still lingering over the Pilbara, Thursday could also bring a further 10 to 20 millimetres to that region as well.

The latest rain comes in addition to two previous systems in the last month, including tropical cyclone Seroja, which already brought heavy falls to the south-west land division.


© ABC 2021

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