South Australia is in for widespread rain in the next few days, possibly leading to flooding in the north, and giving Adelaide its wettest start to the year in more than half a century, according to weatherzone.com.au.

“By early next week almost all of the state will have had some rain. But there will be a large variety of rain amounts, the most in the north and west and the least in the southeast,” Weatherzone meteorologist Brett Dutschke said.

“For central parts, including Adelaide, the rain will arrive on the weekend, affecting the Clipsal 500. We’re not talking a lot of rain, only about five to 20mm, but it will be on and off for most of the weekend,” Dutschke said.

This will also be enough rain to keep Adelaide running at about double the average for the year so far. The city has had 110mm and the long-term average to mid-March is about 55mm.

The previous wettest start to a year was in 1974, when 121mm had fallen to this date.

If the city gains at least 12mm this weekend, it will be the wettest start to the year since 1946.

“A fair bit of moisture and humidity is being drawn down from the tropics ahead of a cooler change, similar to a few other occasions in recent months, but rain will generally not be as heavy.”

As far as flooding goes, the biggest risk is in the northeast, where water is still flowing down the Cooper Creek to Lake Eyre from southwest Queensland. Thunderstorms on Wednesday brought 21mm to Moomba, which has more than 180mm so far this year, three times the average.

Apart from the Northeast Pastoral, some minor flooding is also a chance to extend to the Mid North and West Coast, where there is potential for 50mm or more.

For the River Murray, which is rising downstream of Blanchetown, there shouldn’t be much of an increase. Less than about 15mm is forecast for the Murray and South East – good news for most Mallee farmers who are still coping with last week’s heavy downpours.

It will be a fairly slow-moving system with rain not totally clearing from the state until mid-next week.

“Looking further ahead, La Nina is on the way out and moisture in the tropics is decreasing so the chance of heavy rain will become less with each month as we head into winter,” Dutschke said.

– Weatherzone