Widespread rainfall is ongoing as per forecast through recent days, the risk of riverine and flash flooding ongoing, thankfully the air has been rendered stable at the surface so the severe weather risks are reduced under such an arrangement. But the rainfall impacts are remaining the same with elevated chances of heavy falls for northern and northeast NSW.

The rain coverage eases during Monday, it is still about, with a few thunderstorms too. The drier weather continues for southern and western areas as a ridge noses in.

BUT, that does not last long, a second low pressure trough and low pressure system is anticipated to develop in the broad northeast flow, leading to widespread showers and thunderstorms redeveloping. The coverage more extensive than what we are experiencing right now.

There will be slow clearance by the end of the week as this trough moves east and northeast with a drier southwest flow emerges with new high pressure ridging in by next weekend.

Lets take a look


Rainfall Next 10 Days

Rainfall is heavy tonight, with some locations set to record yet another month's worth of rain, possibly more. The rain contracts east as the trough and low stalls over the northeast and weakens in the northeast to easterly flow. The weather will briefly clear over southern and western areas before the rain and thunderstorms return from the west with some of the rain turning heavy at times with severe weather possible. This will develop from later Tuesday through Friday with rain clearing north and east this weekend. Again, some locations could record up to 1-2 months worth of rainfall. The showers may persist over the northeast third of the state while drier air moves north later in the outlook. Rainfall returns quickly after this period. Still a low confidence forecast based off the rainfall being connected to thunderstorms.

Thunderstorm Forecast Monday

Thunderstorms are expected to be ongoing through northern and eastern areas overnight through Monday morning though the focus will emerge once again over the northeast with heavy rainfall leading to flash flooding a chance before dawn about the coast and in the afternoon along the QLD border. The risk lower than today.

Flash Flood Risk Monday

Flash flooding this evening will continue for parts of the North Coast and Mid North Coast on convergent easterly winds.

Riverine Flood Risk - This Week - Wednesday through Saturday

Additional rain and thunderstorms with heavy rainfall will see additional flooding potential for large parts of the inland. While some areas avoided the heavy falls this time around, we won't avoid it mid to late this week.


00Z Euro - Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

The pattern remains dynamic and unstable and volatile for many regions over the coming 10 days. The forecast confidence therefore remains low with such a large amount of moisture, high degree of instability and low pressure also working through the moisture producing thunderstorms, the placement of the worst of the weather is hard to pin down. There is no doubt that the west will see conditions ease with that low pressure system lifting east into SA then into the eastern states, the rainfall and thunderstorms increasing over SA, VIC, NSW and QLD for the second half of this week. Where the confidence falls down is in who gets what and when. So that is going to be the frustrating part for many this week, with headers sitting still and a lot of water coming down in the east and potential for more. The northern tropics also looking unsettled with high levels of moisture and the return of colder air aloft, supporting showers and thunderstorms. There is a high chance that parts of NSW and southern QLD does not evade the moist air through this period meaning a wet start to December is likely. The west remaining hot in persistent easterly winds.

00Z Euro - Precipitable Water Values - Next 10 Days

Deep moisture still remains in place for much of this week leading to elevated rainfall chances for many. But once we get into the latter part of this week, SA and VIC should return back into dry air and this will support a few days of dry settled skies with southeast winds. Can the humidity be swept out of NSW and QLD? Not so sure on that, which may pose a problem for those needing dry clearer days of weather. It is not looking as promising in these regions, especially the further north and east you go. WA dries out from Tuesday.

00Z Euro - Rainfall Accumulation - Next 10 Days

Refer to video for more details and to the post after 9pm EDT.

00Z Euro - Rainfall Accumulation - Next 16 Days

Refer to video for more details and to the post after 9pm EDT.

More on the rainfall after 9pm EDT.

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