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Storm-producing juggernaut drenching the west

If you asked a young child to colour-in a map of Western Australia with crayons, you might get something that looks a lot like the three-day projected rainfall map for this week.

Rain, and plenty of it, is set to soak virtually the entire state. And while some places will inevitably only see a few drops or miss out entirely, plenty of areas will see good falls.

Image: Three-day accumulated rainfall totals in WA to 8pm Friday, November 22, according to the ECMWF model.

That includes arid areas in the centre and east of the state which are dry at the best of times, and southern areas where rainfall tends to dry up at this time of year.

This event has already well and truly kicked off, with solid falls recorded on Tuesday into Wednesday morning across the Kimberley, Gascoyne, Pilbara, Goldfields, Central West, Lower West, South West, Great Southern and Central Wheat Belt forecast districts.

Some of the rain has fallen briefly in heavy bursts during storms, while in some places it has accumulated steadily. Totals of note from 9 am Tuesday to 7:30 am Wednesday (AWST) include:

• 50mm or more at multiple locations in the South West forecast district, including Shannon and Bridgetown.
• 40mm at Golden Grove, a copper, lead, silver, zinc and gold mine in arid country about 250km east of Geraldton in the Gascoyne forecast district.
• 29.4mm at Kalgoorlie, the heaviest day of November rainfall in five years for WA's largest inland city.
• 28.2mm at Morawa Airport in the Central West, and bear in mind that the site’s average rainfall for the whole of November is just 10.6mm.
• 18.4mm at Dalwallinu in the Central Wheatbelt, where the average for the whole of November is just 13.4mm.
• 17.2mm at Marble Bar, the heaviest daily fall since June this year.

Image: The 7am combined radar and satellite image revealed cloud over a broad area of WA with rain and storms heaviest over inland parts of the state’s western half.

As the image above shows, there's cloud but not much rain on the Perth radar this morning, although 3.8mm did accumulate in the city’s main gauge from Tuesday afternoon into Tuesday evening, with slightly higher totals in many suburbs.

While Perth daily totals will likely remain below 10mm this week before the weather clears in time for the first cricket Test between Australia and India starting on Friday, there's plenty of potential for further solid falls elsewhere in WA.

What's causing this rain?

The broad low pressure trough which is currently causing the rain and storms will be bolstered by an upper-level trough passing over the state during the next few days.

The arrival of that upper trough will destabilise the atmosphere and cause the surface trough (and associated rain and storms) to spread east – hence the coloured-in effect across the state on the map at the top of this story. 

We’ll keep you posted on notable rainfall totals in Western Australia in coming days.