Heavy Rain, Flood Threaten South-East QLD

I am Angus here at the Bureau. This is a Severe Weather Update.

If you are looking outside your window, you might be thinking, "What is he talking about?" because it has been a hot, sunny day so far across south-east Queensland. But that is going to change tonight for a couple of different reasons.

The first of which we can see here on our water vapour imagery, showing where there is lots of moisture in the atmosphere. There has been moisture gradually moving eastwards. This morning, it was centred over the country in the interior here. But look at this high moisture air drifting out to the east. That will reach south-east Queensland by the end of the day today, providing the fuel that will turn into rainfall.

But that is not all.

At the same time that is happening, we also have this change moving northwards up the New South Wales coast, and that is going to have a significant impact on the wind flow tomorrow. In fact, we can zoom in here. This is about midday on Friday, and look at what the wind is doing.

On the southern side of this dashed blue trough line, we have strong southerly winds up from the bottom of the screen. On the northern side, it is a northerly flow down from the top of the screen. That gives us converging winds. Any time we get winds from two different directions that converge together, that is ripe for storm and rain development. This can generate some very heavy falls right along this convergence line.

So the combination of converging winds and high moisture in the atmosphere is going to bring rainfall to large parts of Queensland.

These are the rainfall totals just out to the end of the day Friday, and the reds on the map show us where we expect to see more than 50 mm. That is quite extensive, from south-east Queensland into the Wide Bay-Burnett region, across the Darling Downs and Granite Belt, even into parts of the Maranoa and Warrego, Central Highlands and the Western Forecast Districts.

The heaviest rain is likely to be down in this area here, and that is where we have our Heavy Rainfall Warning, which has just been issued a short time ago.

In fact, we can zoom in a touch further to get a slightly more detailed view of which places are in the warning region. It extends from Coolangatta up towards Maroochydore on the east coast, of course including all of the Brisbane metropolitan area. Then inland, it extends west through Ipswich, Toowoomba, up to Kingaroy and Dalby, and almost as far as Miles. So it is a broad region under warning.

The warning time starts late Thursday and goes through until midday Friday, but we could even see more rain after midday on Friday. For now, the warning is in place through late Thursday and Friday morning. Across that time, in each six-hour window, we could see 50 to 90 millimetres of rain in these areas, with isolated spots potentially getting up to about 150 mm of rain.

That is a lot of wet weather to come down in a six-hour period. If we do start to see these numbers, it is likely to have a significant impact, particularly in terms of flooding, where both flash flooding and riverine flooding are possible.

Flash flooding is where flooding can occur anywhere the rain is just too heavy to drain away. Riverine flooding is when rain falls across a river catchment area, water levels rise, and then flooding can occur further downstream, away from where the heavy rainfall fell.

Both of those are possible in the next 24 to 36 hours.

Water on roads can cause significant transport delays and road closures, and can make for some long detours, so do try to minimise your travel once this rain sets in. It is also possible we could see some infrastructure or power outages and other related issues.

This is going to be an ongoing wet weather event as well. The warning talks about Friday, but we could continue to see areas of rain on both Saturday and Sunday. So throughout the coming days, definitely stay up to date with your forecasts and warnings.

Of course, listen to and follow all advice from your local emergency services as well.

Thanks for watching, and stay safe.