A CLOSER LOOK AT THE SEVERE WEATHER DEVELOPING OVER QLD AND NSW THEN INTO VIC.

The rain and thunderstorm activity is continuing to move east from SA and a trough that is currently sitting through western QLD, NSW and on the eastern border of SA is expected to be the focus of wild weather, particularly where the air is warmer and more unstable, which will be over NSW and QLD.


The mitigating factors today, cloud cover ahead of the trough which may suppress the most severe weather, but it is important to forecast all modes of severe weather today as the atmosphere is a powder keg and the wind fields aloft support damaging weather.


A few points to note before we look at the data


  • There will likely be areas that escape heavy rainfall as the low pressure system redevelops over Central NSW and dives southeast and the trough attached, snaps northeast. This will leave a region of NSW and maybe southern QLD drier than the forecasts suggest

  • Thunderstorms will deliver 50-80mm of rainfall in an hour and no one can tell you where that will happen within a very broad area of risk. If you are under the risk of severe thunderstorms today, be prepared and hope for the best that none of what is forecast evolves.

  • Severe thunderstorms likely to be focussed on the trough as that marches through the soupy air over northern NSW and QLD today and again tomorrow, but the risk contracts east.

  • The heaviest rainfall for the southern and central inland of NSW is determined by where the low reforms and travels. The heaviest rainfall near to the east and south of this feature.

  • The rainfall over southern NSW, VIC and the ACT during Friday night and Saturday is expected to be determined by where the small scale lows travel around the main circulation offshore the South Coast of NSW.

  • Flooding is underway in multiple regions and states and these may increase further if higher rainfall is observed in the coming 24 hours.


Euro Surface Pressure Pattern and Rainfall - Next 3 Days

The Euro carries the low through from SA through western and central NSW, with a broader low developing over central NSW during Friday before that moves to the southeast of the state during Friday night. A few small scale lows will rotate around the main centre of circulation bringing enhanced cold rainfall Friday night into Saturday with moderate falls for parts of southern NSW and the ACT. The north and west clears up by tomorrow evening with a drier southwesterly moving in so the weekend looks rain free.

Rainfall Accumulation - Next 3 Days

Numbers are coming up for parts of southern NSW but note the northwest is drier where the systems split. This could occur further south and east dependent on where the low tracks. Numbers are coming up over southeast NSW, the ACT and the southeast of VIC. Heavy rainfall may be reserved for far northeast NSW and into southern QLD sparing a lot of the north of NSW which has seen a barrage of rainfall and record rainfall totals in some locations leading to flooding.

CMC Surface Pressure Pattern and Rainfall - Next 3 Days

This is showing the path of the low as a deeper feature over SA with rainfall further south. That has verified this morning and this model then shows the low passing through with heavy storms to it's north near the trough. The heaviest rainfall for southern and central parts of NSW is near the low pressure system's path and particularly east and south of the feature as it runs into deep moisture levels in place. You can see again, some areas missing out on the heavier rainfall with the split between the low moving southeast and the trough moving northeast over the eastern states. So there will be areas that miss out under this scenario.

Rainfall Accumulation Next 3 Days.

Note the uneven distribution of rainfall through the east and some areas are quite dry, right next to storm tracks that cause significant flash flooding. So this is where the forecast of rainfall is futile as we await convection getting underway.


GFS Surface Pressure Pattern and Rainfall - Next 3 Days

Very similar spread of rainfall as per the above. The rainfall determined by the low pressure system's path. The trough ahead of the system that was linked to yesterday's low pressure system is expected to be reinvigorated by the new trough coming out of SA and the NT and this is where we see the widespread showers and storms develop. This all marches east tomorrow and then the rain and storms over southern NSW and VIC also clears southeast by evening with lingering rain expected for the southeast of NSW, the ACT and VIC through to Saturday ahead of a cold snap. The good news is, we are seeing a drier picture for many inland areas from later tomorrow into about mid next week, though below average temperatures continue.

Rainfall Accumulation Next 3 Days.

Latest GFS focusses the rainfall a little further west and peaks it through VIC with severe storm tracks through NSW determining the places that get the heaviest rainfall.

Stay weather aware today and the forecasts will continue to chop and change as the models track the low in real time from SA.

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