Perth weather: Bureau of Meteorology reveals reason smoke ...

A thick blanket of smoke slowly made its way across Perth on Monday, prompting health warnings and reduced visibility for residents and motorists.

The Department of Fire and Emergency Services issued a smoke alert for communities between Perth and Jurien Bay after bushfires near Manjimup and Collie, caused the city to be covered in a grey haze.

According to Bureau of Meteorology meteorologist Jessica Lingard, the smoke was blown hundreds of kilometres to the metropolitan area by a common WA summer weather feature.

“So what we’ve got is a west coast trough. We’ve got northerly winds coming down through the central Wheatbelt, down through the Great Southern and down past the fire,” she said.

“Then as we hit the bottom of that trough line, those winds swing up and around them, and then come back up in those south-westerlies on the other side of the trough and those are intercepting the coastline.

“And then we’ve had northerly winds joining over the metro area, and that’s been bringing that smoke down from there down over the metro area.”

The smoke is expected to clear by Tuesday.

“It might be a little bit smoky again tonight, but that west coast trough is continuing to make its move eastward, and so we’re no longer sort of collecting that smoke from down south and bringing it up because the weather feature that was bringing it up is moving eastward,” Mrs Lingard said.

The issue sparked a series of health warnings and advice for motorists.

According to the Department of Health, smoke from bushfires can cause a range of health effects particularly in vulnerable people such as the elderly, children or people with existing health conditions.

Authorities advised those with asthma and respiratory or cardiovascular illnesses to follow their pre-prepared treatment plan, while people affected by the smoke were told they should contact their doctor.

In the case of smoke hazards from bushfires the Department of Health suggested “it is best to stay indoors until the outdoor air quality improves”.

Main Roads WA also issued a warning on Monday, telling drivers to be extra cautious with the smoke reducing visibility.

“If driving through the area, turn on headlights and drive slowly. If you cannot see clearly, pull over to the left, keep your headlights and hazard lights on, and wait until the smoke clears,” authorities said.