The Pilbara ‘dome theory’ debunked

A secret government plot to control weather, the Woodside flame, radio interference . . . there are several theories as to why weather radars regularly show circles of rain around Pilbara towns, otherwise known as the “dome theory”.

Removing the tinfoil hat, Bureau of Meteorology community information officer Daniel Hayes said numerous factors contributed to the “dome” effect.

“This is something that comes up right across the country with any of the radars because there are a number of effects that can impact whether what’s actually showing on the radar is fully representative of what’s out there,” he said.

“Weather radars are predominantly a line of sight, so we have a radar sitting on the top of a tower and it sends out microwave beams in a straight line.

“It gets reflections back off the weather, basically the interface between the air and the water in the cloud droplets, or the rain droplets that are falling out of the cloud, and that shows up as a return signal.

“Another thing that can occur is anomalous propagation. There are atmospheric conditions, things like inversions that can cause those beams to bend somewhat, so they’re not actually going in a straight line, which means that you can get reflections back from the surface.”

Pilbara News also spoke to the local legend known to social media users as “Pilbara Weather Guy” about the region’s dome theories.

“People in Exmouth, Karratha, Onslow and Hedland all claim there is a dome as storms seem to go around the towns, which does appear a bit odd,” he said.

“There are some unfounded theories around, from salt ponds to iron ore on the ground. It goes pretty extreme where some people are very adamant that the sky is being controlled with sprays and technology that we’re not aware of.

“As for the Woodside flame theory, the flame would only have a very minor effect, but not enough to prevent any weather system going through it.

“it would be like using a pencil to stop the tide coming in.”

Pilbara Weather Guy said the “dome” was mostly a result of the sea breeze.

“On the coast, you get the sea breeze most afternoons, and that helps form what we call a convergence line, and that’s why when you look inland, all those nice, puffy, white storms form.

“They form because you’ve got that sea breeze and the inland heat. They all come together and you get that trough that forms.

“Generally speaking, they want to move towards the coast, because that’s usually the way the wind wants them to go, but the sea breeze kind of blows them away, or they just collapse.”

The Pilbara landscape also influences rainfall in the region.

“For Karratha, it sits within a ‘bowl’ between the coastline, the marsh and ridges behind — it acts like a protective, upside-down dome,” Pilbara Weather Guy said.

“Hedland is a little bit different. It’s a little bit closer to the tropics, and because Hedland sits between two landmasses, there is an effect where the storms form up towards the De Grey River, and sometimes when the winds are coming in from the north, the storms can come over Hedland.

“But Hedland is similar to Karratha in that it has the same sea breeze effects and no mountainous areas to really lift with the clouds and change the weather.”