The rain locally heavy this weekend with pockets of flash flooding a moderate chance at this stage and the chance of renewed minor flooding and peaks along existing flooded rivers at the moment through the state's south.

The north of the state may be dealing with showers and local thunderstorms with the chance of some of those becoming severe this weekend.

The far west may see reasonable rain but as you move north up the SA border the lighter the falls will be if anything.

So a mixed bag throughout the next 5 days.

There is the chance for follow up rainfall as well which may produce further widespread rainfall from this time next week but I have not got great confidence in that just yet. But it does lurk on the models this evening.

Lets take a look


Rainfall Next 10 Days

Rainfall is expected to be filter through with a weakening trough on Friday through southern areas but it will be patchy and light with a lot more cloud about. There maybe a few thundery showers about the south and southeast with a weak southerly working north. The bulk of the rain comes from Saturday, spreading from the west early and turning to more persistent areas of rainfall with a few thunderstorms. To the north and east of the cloud, there is the chance of strong to severe thunderstorms Saturday afternoon and again on Sunday with locally heavy rainfall but the rainfall more uneven in distribution. As we track into early next week, the low pressure moves off and fine weather resumes before that next trough and low develops from the north and west which offers more rainfall.

A closer look at where the flooding may be of concern this weekend - these numbers will refine.

Thunderstorm Forecast Thursday

Thunderstorms are possible about the northeast during the afternoon and evening inland of the coast, where convergent winds meet and lifts cloud over the top of the dividing range. No severe weather is expected. There may be some high based showers and thunderstorms over VIC which may clip the far southern Riverina later tomorrow night.

Riverine Flood Risk - This Weekend

With additional heavy rainfall developing this weekend over existing flooding, there is a chance of further flood peaks and other catchments moving into flood status this weekend. Stay up to date on all the forecasts.

DATA - Refer to the video to see CMC and the comparison

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

The GFS has moved further into line with the CMC which I believe has been handling this first system best. We have a junk type system passing through WA into SA then VIC and TAS Thursday and Friday with patchy rain and thunder possible. Moisture is limited as mentioned. Showers return to the tropics with thunderstorms about. Isolated strong storms possible through southeast QLD and northeast NSW inland of the coast Thursday. Areas of rain likely to increase over the southeast of WA and enter SA through Friday into the weekend with the more dynamic system moving through. The system reaches VIC and NSW Saturday and moves east of these states during Sunday. Rainfall heavy at times over the southeast with this feature which maty renew flooding. There may be strong to severe storms in the warmer sector north and east of this feature over the remainder of NSW and southern QLD Sunday. Then conditions clear for early next week in these regions. Thunderstorms increasing over the tropics from the weekend through next week with that moisture surging south into QLD and the southern NT and this may be captured by a follow up trough which, if it develops, could spread rain and thunderstorms throughout the southeast and eastern inland of the nation once again. The west turning warmer and drier throughout this period with the wet weather over the east of the nation.

00Z GFS - Precipitable Water Anomalies - Next 10 Days

Humidity is on the rise as mentioned throughout this period. The monsoonal flow is about 4-5 weeks away from northern Australia and once that increases over the north of the nation, the weather will turn even more humid and wet across the nation. The drier days will be hard to find. While you may not see a lot of green on this chart, the tropics are soupy to start with so if you see greens and blues up there, that is a huge issue for those not wanting severe weather, rainfall or humidity to extend across the nation. This run of GFS is a lot drier than the ensemble data set that I have seen throughout the day.

00Z GFS - Precipitable Water Values - Next 10 Days

With the system passing through the nation in the short term, it will be tapping into PW values of 30-50mm across SA through NSW and VIC which will lead to extensive rain and thunderstorm activity. The thunderstorm coverage will be more active in the regions that can break through to the low 30s this weekend. The deep moisture profile remains in place until the end of the period over northern Australia and especially through the Coral Sea and Indian Ocean but note the mobility of moisture over the Coral Sea and its advance towards the east coast of QLD and through the tropical north.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to video for more

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to video for more

00Z Euro - Rainfall Accumulation - Next 7 Days

But note as we zoom in - the shifting of the rain band further north on the Euro....your number will continue to change. The band is narrow and for example some parts of the Eyre Peninsula could get 5mm and 30km up the road - 50mm. Those in southeast NSW pay attention to the rainfall turning heavy in future runs. I have already drawn that in on my forecast and I may expand the flood risk to include areas east of the divide.

I will have more on all things rainfall and modelling coming up after 9pm EDT tonight.

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