Severe Storms to Hit NSW, SE Qld 10 December

So starting with today, we can see this trough over in the east. Now that's the weather system that brought the cool change to eastern New South Wales yesterday. And also another trough extending down from the north. Now that is starting to drag moisture into northern New South Wales. Combined, these two systems are bringing showers across eastern and northern parts of the state. And some of these showers have already started to produce thunder and lightning.

So looking at our thunderstorm forecast, we can see these dark green areas showing where thunderstorms are possible. And it's across much of eastern and northern New South Wales. The light green areas show where thunderstorms are likely. But it's really this yellow area that I want to focus on. That's where severe thunderstorms are possible. It extends from the blue Mountains up through the upper Hunter, into parts of the Northern Tablelands, and into the North West slopes and plains.

Now the main risk with severe thunderstorms today is damaging wind gusts, which could cause, damage to trees and also bring down power lines. But there is also the risk of large hail and heavy rainfall that could lead to flash flooding. We've actually already seen thunderstorm warnings issued for thunderstorms today, and more may be issued throughout the afternoon, so make sure you stay up to date with all the warnings.

Looking at tomorrow this trough in the east does linger. But the one in the west will start to move towards South Australia, and that will allow more moisture down across the state. Not only will this give us more widespread showers and thunderstorms, but it does increase the risk of heavy rainfall that can lead to flash flooding.

So looking at our thunderstorm risk area, we have a widespread risk of thunderstorms right from north-eastern Victoria, most of New South Wales, apart from the far south-west, and up into Queensland. But this severe thunderstorm area covers a large part of central New South Wales and also over towards the east coast. Over central New South Wales we have the risk of heavy rainfall, but also damaging winds and large hail. While over on the East Coast the risk is more around that heavy rainfall risk that could lead to flash flooding. And that risk will increase as we go through the day and the moisture increases over the state.

Into Friday those showers and storms continue over eastern parts of the state during the morning. But as we go through the day, the trough will start to move offshore and we will see these showers clearing and eventually moving offshore. But there is a risk of thunderstorms right from eastern Victoria through eastern and northern New South Wales and up into Queensland. The risk of severe thunderstorms is most likely over northern New South Wales and southern Queensland, but there is this risk of severe thunderstorms over the Central Coast, the Sydney and the Wollongong regions. And now that's really about a risk of heavy rainfall leading to flash flooding. Most likely during Friday morning. That risk will decrease as we move through the day.

So before we talk about how much rainfall we're expecting with this weather system over the next few days, let's talk about some of the severe storm impacts. With increasing moisture, the risk of heavy rainfall leading to flash flooding is one of the main risks, and that is where we see drains overwhelmed and also small creeks and streams rising really quickly. Now that can lead to road closures and detours. We also have the risk of damaging wind gusts and large hail, which also combined with heavy rain, can cause damage to property, trees and crops.

In terms of how much rainfall we're expecting over this weather system, we're looking at the rainfall from this morning right through to the end of Friday, and we can see these large orange areas across eastern and northern parts of the state. That's when we're expecting to see moderate rainfall of 20mm, maybe up to about 40 or 50mm. But it's really these pink areas that show the risk of rainfall of 50mm or more. And some of these dark purple areas even showing the risk of up to about 100mm, or even a little bit more with severe thunderstorms. Now, the patchy nature of these pink and purple areas does underline the hit and miss nature of thunderstorms, and not everybody will see these higher end rainfall totals. But there's certainly a risk of moderate to heavy rainfall across much of eastern and northern New South Wales over the next few days.

Now, thunderstorm warnings have already been issued and more will be issued today and over the coming days as thunderstorms develop, or are expected to become severe. It's important to stay up to date with these warnings on the Bureau's website or the BOM weather app, and to follow all advice from your local emergency services. And please stay safe.