A weather event brewing across south-eastern Australia will bring widespread severe thunderstorms to some parts, heavy rain and damaging winds to others, mostly affecting New South Wales, Victoria and ACT. I’m Angus here at the Bureau of Meteorology. It’s the 14th of January, and here’s an update about what we can expect in the next few days across south-eastern Australia.

Let’s set the scene, paint the picture, if you will. Our main weather feature at the moment is this fairly innocuous looking dashed blue line. That’s a low pressure trough, which for Wednesday, for today, is sitting slow moving across western New South Wales, also tailing into eastern Victoria as well. As it does remain fairly slow moving on Wednesday, it’s helping to draw in very humid air from the east, which is going to fuel this weather event in the coming few days.

As we play through now, tomorrow into Thursday. Initially, it looks much the same. This low pressure trough does not move very fast on Thursday morning, but throughout the course of the day it will deepen and intensify, and eventually we’ll see a low pressure area develop along this trough line. There it is, popping up over western New South Wales. Now, that low pressure area is going to act to enhance the overall weather event, bringing heavier and more widespread rain, as well as stronger winds through southern and eastern Victoria and eastern New South Wales and the ACT.

There will be significant thunderstorm activity over the next few days, peaking on Thursday. But we’ll start off with a look at Wednesday’s thunderstorm forecast across eastern Australia, because it’s already getting quite extensive for this afternoon. Severe thunderstorms are possible on this map in the yellow area, and severe thunderstorms today could bring any of the following hazards, damaging wind gusts, heavy rainfall that leads to flooding, or some large hailstones, and the area is much of inland New South Wales and all of the ACT. Just gets across into parts of Gippsland and eastern Victoria as well.

Now, we’ll probably see an enhancement or an elevation of the severe thunderstorm risk for tomorrow, for Thursday. And now the yellow area where severe thunderstorms are possible gets even more extensive, all the way out to the north of the state and into southern Queensland, through much of central New South Wales, through the Illawarra, through the south coast, and about half, or almost half, of Victoria, from the far eastern suburbs of Melbourne. And you can see we’ve also added a red area onto the map where severe thunderstorms are most likely to occur on Thursday.

Supercell thunderstorms could bring areas of very heavy rain and flooding through this region, as well as damaging wind gusts and large hailstones. In particular, we’re looking at southern parts of the south coast forecast district, the Southern Tablelands, Snowy Mountains, ACT, and north-eastern ranges of Victoria as the most likely areas to see severe thunderstorms.

Some of the key weather impacts that could occur where these storms do happen in the next few days include flash flooding, where the water can rise very quickly underneath very heavy rainfall. We expect stress on the power network and potential power outages, and the wind can bring damage to trees and crops across south-eastern Australia as well.

Now, thunderstorms are just one part of this weather event. Outside of the thunderstorm risk, there is also going to be significant widespread rainfall across a number of areas in the south-east. So this map is showing rainfall for the next few days, all compiled onto the one map. We’re now looking at total rain between Wednesday and the end of the day on Saturday.

I’ll zoom in a little bit, and I wanted to highlight a couple of areas in particular. Firstly, where is seeing the rain? Well, one district in particular is really sparking strongly on this rainfall accumulation map, and that is the south coast of New South Wales. Heavy, persistent falls in the coming days there, that includes regions like Batemans Bay, Bega, Merimbula and down towards Eden as well. We could absolutely be seeing triple figures of rainfall there, and we probably will see 100 mm to 200 mm. And if those thunderstorms get going, we could definitely see even more than that with heavier falls in the coming few days.

So that is absolutely an area to pay attention to, probably seeing the most rain of anywhere in the country between now and the weekend. I also wanted to highlight some areas that are not getting much rain, and this is crucial because of significant bushfires that are still burning in Victoria. Especially in the north-east where the Walwa fire is burning, and through parts of central Victoria, where the Longwood fire is burning.

Both of those areas are on the northern side of the mountain ranges. And as we can see on this map, by far the more significant accumulations are on the southern side. So across these key fire grounds, we’re really looking at around about 5 mm to 10 mm of rain in the coming few days, which is not enough to put out any ongoing bushfires. And in fact, because this weather event is not only wet, but it’s also going to be windy, we could potentially see some gusty, strong south-easterly winds pushing across those fire grounds and maybe making those fires flare up once again.

Some other key impacts that we do expect to see with this rainfall, especially around the south of New South Wales, slips and landslides are possible with days of persistent rain on end, closed roads absolutely possible, some long detours if you’re travelling cross-country, and of course, those gusty winds could be blowing over those bushfire areas in Victoria.

It is going to be very active through the end of this week and staying that way through the course of the weekend. So definitely a good week to check your emergency supplies, stay up to date with your forecast and warnings, and do follow any advice from your local emergency services and emergency management. Thanks for watching.