Australia Weather News

Heavy rainfall, a strange skyline and a waterspout over the ocean are just some of the weather phenomena witnessed across Western Australia's Pilbara region over the past 24 hours. 

The stormy weather has delighted many locals who watched on in awe.

Dampier resident Eloise Dortch was out walking her dog on Monday morning when something caught her eye off the coast.

"I didn't know what I was looking at," Ms Dortch said.

"I saw this weird, dark trail going from the rain clouds down into ocean.

"It was there for quite a few seconds, and at the base where the spout went into the ocean you could see a flurry of water spray."

Tornado on water

Ms Dortch was witnessing a waterspout, a weather phenomenon that usually only lasts a few minutes, before dying down.

"It was fantastic," she said.

"Walking on the Dampier foreshore regularly, you see all kinds of things."

Bureau of Meteorology forecaster Jessica Lingard said with strong thunderstorms there was a risk of tornadoes forming underneath them.

"Basically, it's a result of the spiralling air coming into the thunderstorm, you can get these rotations happening at the bottom of the storm," Ms Lingard said.

"If a tornado forms over land, we call it a tornado – if it forms over water, we call it a waterspout.

"So it is actually a tornado that forms underneath a thunderstorm."

Ms Lingard said it was possible for waterspouts to move onto land, but that was rare.

"They are quite spectacular when you see them out of the ocean, they spin up all the water, there is a lot of spray associated with them.

"But you do need to be careful because they can have some decent gusts with them; they can do a lot of damage."

'Optical illusion'

Residents in Karratha and Dampier have also been sharing photos of a strange line that appeared to bisect the sky on Sunday evening.

Ms Lingard said the spectacle was actually the result of shadows hundreds of kilometres away.

"Either a big storm or a tall, cumulonimbus cloud, which is going to provide that nice shadow," she said.

"We can even get them off topography if there's a big hill in the way."

She said the incredible "optical illusion" could actually occur fairly frequently. 

"It just depends on what the weather is doing either to the east or west."

Heavy rain forecast

A severe thunderstorm warning was issued by BOM Monday morning for Tom Price and Paraburdoo due to concerns about heavy rainfall.

Paraburdoo received 35.4 millimetres in a 30-minute period from about 4:20am, with a total of 61mm recorded at Paraburdoo airport. 

Karratha recorded 35.6mm of rain, while 45mm was reported at Bonney Downs Station, near Nullegine.

Michael Percy from Yalleen Station, south of Karratha, said the 34mm they received over the weekend was a great relief.

"We had a pretty dry year last year, and we definitely needed rain," he said.

"They're pretty localised storms, but there's been enough of them that they're sort of covering the country."

The BOM says more thunderstorms are likely in central parts of the Pilbara, as well as possible damaging wind gusts and heavy rainfall in inland parts of the Kimberley.

It follows other recent heavy rainfall in the Pilbara, including 77mm at Indee Station on December 31, which got the Harding River flowing. 

Two tropical lows

As well as thunderstorm activity, the BOM is monitoring two tropical lows off the WA north coast.

Tropical Low 10U is expected to remain slow moving this week.

11U may form off the Kimberley coast later this week or over the weekend.

Ms Lingard said a monsoon trough was expected to have an impact. 

"Once that monsoon trough drops into that region it's going to enhance all of that," she said.

"Troughs are low-pressured, so are cyclones, so they go hand in hand."

Both systems have less than a 15 per cent chance of forming into a cyclone.

However, the BOM says the lows could still bring extra shower and thunderstorm activity, especially along the western Kimberley and Pilbara coastlines.