SA and VIC, boring and benign so rinse and repeat weather for you lot, that is how it rolls in Summer time across the country.

The major weather features to watch is still the deepening tropical low over the northern tropics and the potential east coast trough and deepening moisture profile with heavy showers and thunderstorms forming in the coming days but the potential for widespread rainfall and heavy falls could be in place this weekend into next week.

The rainfall over the east could turn heavy this weekend as outlined in a post earlier this afternoon and that will need to be watched for flood potential through the region, ahead of any potential spread of moisture from the north of the nation.

For the west of the nation, baking hot, with a large scale upper high and easterly winds sending in desert air for a number of days, excessive heat warnings in place for this weekend. Nothing unusual for Summer but it is going to be a hot Christmas.

Southern parts of the nation sit under the ridge, but on the onshore and cross shore flow with mild to warm and mostly dry conditions for now.

Lets take a look


Rainfall Next 10 Days

Rainfall mostly unchanged from this morning and remains low confidence as we await two elements, the main one the monsoon, and how that passes through the northern tropics and how the tropical low performs and travels into next week, whether it stays up north, or goes south or southeast through the nation. The other element, the trough on the east coast, with onshore winds and showers and thunderstorms developing, but to what degree does that moisture get drawn into the eastern inland of NSW and QLD and how far south does that seep. Many issues to iron out so for now the wettest part of the nation is northern and eastern Australia. Mixed odds for the interior and mostly dry for southern and southwest Australia.

A closer look at the other area of severe weather potential, along the Northern NSW and SE QLD coasts.

Thunderstorm Forecast Thursday

Thunderstorms back over the same locations once again on Thursday with the coverage shifting south and west through NSW and into the ACT with some storms turning severe. The trough over the east snakes back over the eastern and southern inland of QLD. The thunderstorm coverage is expected become more widespread over the NT and Kimberly with some storms gusty, especially over the southern and western NT into the north of the Kimberly.

Thunderstorm Forecast Friday

Thunderstorms contract north into northern NSW and into southern QLD with a trough sharpening in response to high pressure ridging through southern Australia. This will allow for more moisture to surge into the southern end of the trough. Flash flooding a chance for the eastern inland of NSW and into southern QLD. The storms will again snake back over northern parts of the nation, storms may turn gusty again.

Thunderstorm Forecast Saturday

A tropical low deepening to the north of the NT will see storms turn gusty and severe with heavy rainfall leading to flash flooding and possibly one or two brief tornados over the northern coast. The storms will develop further south over much of the NT, through QLD and into NSW and the ACT again. The storms over the eastern inland could be heavy at times with flash flooding the main risk

Tropical Depression Risk - Friday through Monday

Tropical depression risk is above 75% chance over the course of the weekend with a low emerging from the Arafura Sea and heading south into the NT, but location to be determined. Further tropical depressions are likely to form along the monsoonal trough as we roll into early January.

Tropical Cyclone Risk - Friday through Monday

A moderate risk of cyclone development with the low sitting in a favourable position for further development this weekend. Category 2 at best north of the NT before it encounters wind shear closer to the coast and the system likely to weaken on approach.

DATA - Refer to video for more

00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

No major changes to the synoptic pattern and the models are going to struggle under the changing nature of the tropical feature north of the NT. The weather over the east coast, is remaining unsettled with a significant chance of widespread rainfall and onshore winds and below average temperatures for a good chunk of the next week. Otherwise no major change to the weather for southern and western parts of the nation closer to the high pressure ridge leading to settled skies and warm weather for VIC and SA and hot to very hot over the southwest of the nation. Depending on the tropics, the weather out west could be very hot for up to 10 days with little rainfall. The weather may begin to shift as we move into January for SA and VIC with moisture spreading south and southeast out of the monsoonal flow into troughs moving through the eastern and southern inland, but the weather largely quiet for now in these zones.

00Z GFS - Precipitable Water Values - Next 16 Days

The deeper moisture over the north and east will continue to spread throughout during the period, reaching northern SA and much of northern NSW from the end of the weekend if not next week. The weather out west dry, hot and settled closer to the ridge still, no change from this morning.

00Z GFS Ensemble- Rainfall Accumulation - Next 16 Days

Refer to video for more

00Z CMC Ensemble - Rainfall Accumulation - Next 16 Days

Refer to video for more

00Z Euro Ensemble - Rainfall Accumulation - Next 16 Days

Refer to video for more

More coming up tomorrow from 8am EDT. I will be doing more posts on rainfall once we get better idea of the tropical low pressure up north and how that evolves as all models diverge on the idea as mentioned in this evening's video.

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