Australia bushfires: 50mm of rain needed to extinguish fires edited by Ferratum

Tropical Cyclone Claudia has brought a deluge of rain to Australia’s north and some of that wet weather is expected to bring relief to parts of the country’s east this week.

The cyclone, which has now strengthened to a category three storm, is dumping huge amounts of moisture on the Northern Territory – on the weekend, a record breaking 500mm of rain fell in parts.

While potentially as much as 50-100 mm of rain could fall in some areas of Queensland, New South Wales and Victoria coasts during the next week, forecasters have warned that sustained rain – rather than a downpour – will be needed to extinguish the nation’s bushfires.

HOW MUCH RAIN IS NEEDED TO PUT OUT A BUSHFIRE

There are three factors that determine how much rainfall is needed to put out a bushfire, said Sky News Weather channel Chief Meteorologist Tom Saunders.

“It’s a very difficult question to answer, because it does depend on the size of the fire, how intense the rainfall is, and also the types of vegetation that fire is going through,” Mr Saunders said on Tuesday.

Less than 10mm of rain will have no impact on a fire, he said. This amount also wouldn’t slow the fire down, and could hinder back burning because, if the vegetation gets wet, small fires are unable to be started in the path of the main fire.

Moderate rain, between 10 and 20mm, has the potential to slow down a fire, but won’t extinguish it.

And if the light or moderate rain is the result of a thunderstorm, “there will be negative impact, because thunderstorms have lightning, and if they’re not producing much rainfall that lightning – called dry lightning – will actually spark up new areas of forest, which will then burn,” Mr Saunders said.

Heavier rain (between 20 and 50mm), which is what’s forecast in the coming days for parts of the nation’s east, has the ability to extinguish a small fire and slow down a large fire.

“If it’s from a thunderstorm, though, a lot of the rain will just run off if it falls quickly,” he said.

“It won’t soak into the vegetation. So 50mm of rain, if it falls in one or two hours, will not extinguish a bushfire.”

Ultimately, what the nation’s bushfire-ravaged east needs is steady rain falling over a couple of days.

“More than 50mm is generally required to slow down an exceptionally large fire, and to extinguish most bushfires you’d need well over 50mm,” Mr Saunders said.

RAIN FOR MOST CAPITALS

Thick bands of rain are creeping down both the west and east of the country, leaving only South Australia and the southern Northern Territory lacking in any noticeable moisture.

Brisbane will be soggy from Tuesday onwards with highs nudging 30C and some heavy showers. Cairns, in the tropics, is looking at about 50mm of rain this week.

The weather has settled in Sydney for the next few days with highs in the late 20Cs. But from Thursday onwards, storms might be seen above the Harbour City with 5-10mm falling each day.

Smoke haze in a warm Canberra on Tuesday where the mercury is forecast to reach 34C. Showers on Wednesday could clear the smoke with heavy downpours and a possible storm on Wednesday setting the tone for the rest of the week.

Drier in Melbourne with a sunny but smoky Tuesday with highs about 30C. Reaching 31C on a humid and possibly stormy Wednesday. Then the temperatures should fall into the low 20Cs, even the teens, as the week goes on with rain here and there.

Hobartwill be warm, in the mid to late 20Cs until Thursday when there could be a 10C temperature drop accompanied by splashes of rain.

Bone dry all week in Adelaide. Temperatures reaching 34C on Tuesday, then settling between 26-29C for the rest of a sunny week.

A hot week for Perth, the highs not dipping below 33C. While the monsoon could bring rain to the north of WA, with storms for Broome and Karratha, little of that will reach the south.

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