There is a lot of weather on the board through the next week and it does not involve just the east of the nation for once! Hot weather developing out west may lead to the first significant heatwave of the season in the coming week.

We have a sharp middle level trough sparking severe thunderstorms today for VIC, southern NSW and the ACT. There will be thundery weather further up the NSW ranges into QLD, but the coverage of severe weather less for QLD which is a relief.

The tropics also screaming out about the monsoon developing into the middle of the month and that may spawn not only early season cyclone activity, but have dire consequences for flood zones leading into Christmas with heavy rainfall possibly returning for the medium term in QLD and NSW.

Lets take a look at the short term first.


Rainfall Next 10 Days

The humid and unstable air is expected to remain over northern and eastern areas of the nation. The confidence in forecasting into about 5-7 days is becoming very challenging with the impacts of the tropics still remaining unknown, some of the global models are introducing a monsoon to the north and some are not, this playing havoc with rainfall output. This will continue. Nationwide, your numbers will continue to change as the modelling becomes clearer on how the weather in the medium term begins to unfold. Until then, the forecast confidence remains low. The highest chance of rainfall is over northern and eastern Australia based off current data but the coverage is uneven. Parts of WA and southern SA could remain rain free through this period with persistent ridging. The southeast sees changeable conditions with fluctuations in temperatures. I will mention that the rainfall coverage in the flood zones may be scattered and not as widespread as first thought as per previous guidance.

Thunderstorm Forecast Thursday

Thunderstorms are forecast to develop over the southeast of the nation today along a strong trough as it passes through from SA. Storms are likely to turn severe with damaging winds and heavy rainfall leading to flash flooding the main concern through parts of VIC. Showers and thunderstorms are likely through the north and east of the nation with the presence of weak troughs and the usual build up activity at this time of year.

Thunderstorm Forecast Friday

Thunderstorms likely to contract into southeast NSW and the ACT with a sharp trough moving northeast. Heavy rainfall leading to flash flooding and damaging winds the main concerns. Gusty storms likely to extend back through outback NSW. The east likely to see a few showers and thunderstorms as per the tropics, high humidity and a weak trough leading to the continuous afternoon activity.

Thunderstorm Forecast Saturday

A stalling trough over northeast NSW and southeast QLD will trigger scattered showers and thunderstorms, some severe with damaging winds and heavy rainfall leading to flash flooding. The tropical weather remaining routine with the risk of some damaging winds with those storms about the Top End.


12Z Euro - Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

The pattern is remaining low confidence as we track a shift in the tropical weather. This happens every year where the modelling becomes more erratic as the models begin to adjust the monsoon into the forecasts. The impacts of the monsoon on the forecast is significant and will play havoc with the rainfall forecasts. In the short term we are dealing with the sharp trough passing through today producing showers and thunderstorms over the southeast. That trough moves into southeast NSW on Friday and into northeast NSW and southeast QLD on Saturday producing more showers and thunderstorms. The west turns hot and windy with a deep heat low over the Pilbara whipping up the hot windy weather. Over the north, the routine weather continues until next week. The tropics and eastern seaboard will likely see the majority of rainfall through early next week near troughs and deep moisture, the southeast and south dry across the weekend and into early next week. The next major change is expected to form from Tuesday through Friday next week with a mid level trough and low deepening as it passes into the east and links into moisture, more showers and storms are expected with humid conditions redeveloping for a large part of the nation. The west remains hot.

12Z Euro - Precipitable Water Values - Next 10 Days

This product depicts the movement of moisture throughout the region and what is available to use to produce rainfall in the presence of low pressure. There is plenty of northern and eastern Australia throughout this period, with the values increasing to around 70mm over the tropics, this hinting the weather is set to get wet and stormy more frequently after this nasty build up. The moisture in the east remains largely unchanged with the persistence of easterly winds and troughs. The west and south looking settled and drier with a easterly flow. This will reduce rainfall chances for now, but that moisture could creep southwest and south.

12Z Euro - Rainfall Accumulation - Next 10 Days

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12Z GFS - Rainfall Accumulation - Next 10 Days

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12Z CMC - Rainfall Accumulation - Next 10 Days

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More coming up through the day, remain weather aware with the severe weather in the southeast today, some of the storms could produce some high impact weather.