A strong upper low is bringing up the chances of widespread showers and scattered thunderstorms on Wednesday to northeast NSW and southeast QLD. Storms have the potential to produce a large amount of small hail and damaging winds as well as a moderate risk of large hail through this region.

Weather Matters - Thunderstorm forecast for Wednesday May 5th 2021

Hail is of concern through the region. Large amounts of small hail could fall with any showers and thunderstorms, but with the dynamic forcing in place with the upper level low over the region, more robust thunderstorm development could contribute to larger hail developing and thus a very high chance has been indicated for parts of the region for this issue on Wednesday.

Weather Matters - Hail risk forecast for Wednesday 5th of May 2021.

Now all of that activity will ease after sunset Wednesday as the storms lose the fuel to keep regenerating. So the severe thunderstorm risk should move offshore.

Further south, widespread rainfall is expected along the NSW coast, with some areas expected to receive 100mm over the coming days along the south coast and up to about Wollongong.

Rainfall forecast for the next 4 days - showing the rainfall becoming coastal.

Thunderstorms in this region may produce localized flash flooding, but the risk is rather low and no forecast chart has been drawn at this time, however this could change if the low pressure system offshore does indeed move closer and passes the coast during Thursday.

The weather should begin to dry out with the passage of the upper low through inland areas Tuesday night, this dry air establishing the dry line which will initiate the severe thunderstorms over northeast NSW on Wednesday before flushing out the moisture during Thursday, except for the south and central coasts.

Precipitable water forecast for the next two weeks - GFS Valid May 5th 2021.

Conditions drying out and stabilizing for much of the inland, however we may see the approach of rainfall from SA through the weekend, with a decaying upper feature moving in. A lot more cloud than rainfall at this stage but it needs watching.

CMC 00z run for accumulated rainfall over the next 5 days - Valid May 4th 2021

GFS 00z run for accumulated rainfall for the next 5 days - Valid May 4th 2021

Euro 00z run for accumulated rainfall for the next 5 days - Valid May 4th 2021.

A stronger front will approach southeast Australia during the latter part of the weekend, sparking the next round of showers and hail for SE SA, VIC, TAS and southern NSW. Alpine snow looks to return as does modest rainfall totals for these areas.

GFS 00z 500mb chart for Monday May 10th - Valid May 4th 2021.

The current GFS does have this system in a more favourable position for rainfall of some note for thirsty SA.

More on that event later in the week as we get better clarity on how the next 3-4 days evolves as that will impact weather upstream out of the west.

Want some more tailored forecasting for your neck of the woods - email me at karllijnders@weathermatters.org