Lets take a look at what is happening throughout the state during the month of September
Rainfall Outlook for September 2021
%chance of exceeding the median rainfall for September 2021
A wet end to August is likely and a wet start to September is also likely for parts of the east and south of the nation. The weather is expected to be dominated by the influence of the Indian Ocean Dipole which is drawing in large amounts of moisture from the northwest through to the southeast, likely lifted by troughs and or cold fronts. I covered off on an example of this during this morning in the morning update. Larger scale inland systems are expected to form as the clash of airmasses from the south and north, coupled with large amounts of moisture from the north and northwest combine to increase cloudiness and rainfall chances. The presence of inland troughs over inland areas of NSW and QLD are also likely to form in the eastern inland which may bring a chance of thundery weather in between rainfall events. The frontal weather may decrease a little during the month as we see a seasonal shift towards warmer weather over northern Australia.
Temperature Outlook for September 2021
%chance of exceeding the median temperatures for September 2021
Now there is a lot of blue on the map for the month of September, with increased rainfall and cloudiness, however that does not mean you will see a cold month, there will be warmth in there too, but with increasing cloud cover and rainfall chances for inland areas, it is safer to surmise a cooler than average month on the way, especially for the second half of September as the guidance suggests rainfall and cloudiness increasing with the Indian Ocean Dipole strengthening. The frontal weather looks to be near normal for the first part of September, opening the door for more rainfall events to descend from the north, spreading thick cloud throughout vast areas of eastern Australia.
The main driver for the month will be the Indian Ocean Dipole strengthening the negative phase. This is expected to peak during the October or early November which will will see larger rainfall events spread across the country, and the eastern inland of VIC and NSW likely to cop the brunt of the rainfall, especially on and west of the divide, where flooding is a risk. The weather is expected to turn more humid along the coast but the rainfall bias will be on and west of the divide for the month for now.
The risk of La Nina is increasing through some data sets this week. The weather is expected to be dominated initially by the Indian Ocean Dipole. But if you live along the coast, pay attention to the upcoming climate outlooks as this is the period where we may get a La Nina watch declared in Australia, and this could see a wet summer develop once again for the east coast.
I will have another update on that during Tuesday.