Not much shift in the rainfall spread coming up for the event developing from tomorrow and continuing through Friday.

The rain may be accompanied by thunderstorms as a trough deepens throughout inland QLD and drifts into NSW, linking up with modest moisture levels to produce the unstable weather.

Key points.

  • Some locations could see half a months worth of rain with a few pockets recording another months worth of rainfall.

  • Thunderstorms could bring damaging winds and heavy rainfall that could lead to flash fooding.

  • A low forming on the trough may bring a burst of strong winds and heavy showers to the Hunter and Mid North Coast.

  • The region turns dry from Saturday.

Let's look at the latest model data

00z GFS Rainfall for the coming 10 days - Valid Wednesday 7th of July 2021.

Rainfall looks to be quite productive over the coming 48hrs for areas close to the QLD border to the western slopes of the Great Dividing Range and the New England. This latest run has a band of heavy rainfall over towns such as Walgett, Coonamble and through to Gunnedah and Narrabri. Moderate rainfall throughout large parts of the northern inland. It does move off Friday afternoon and clears the coast Saturday.

00z Euro Rainfall for the coming 10 days - Valid Wednesday 7th of July 2021.

Widespread rainfall with moderate falls and scattered heavier falls with thunderstorms breaking out during Thursday into Friday then contracts to the coast. Heavier falls are being picked up by this model for the coast as the low deepens off the Hunter during Saturday and then clears. The rainfall focus then shifts to the westerly wind belt over the south from Sunday and more likely from next Tuesday onwards, a system later next week could bring inland rainfall back.

00z GFS Rainfall for the coming 10 days - Valid Wednesday 7th of July 2021.

Rainfall signals, still heavier for the southern inland bordering the NSW region with storms bringing the heaviest rainfall. The rainfall clears out during Friday with a return to dry and fine weather with potentially above average temperatures for central areas and near normal conditions from the weekend over the southern inland.

00z Euro Rainfall for the coming 10 days - Valid Wednesday 7th of July 2021.

Rain develops through Thursday night into Friday with the most persistent rainfall expected during Friday morning clearing from the northwest to the southeast with the passage of the trough, the best of the falls still where storms form and closer you are to the NSW border. Drier weather next week, but now this run of the Euro brings light rainfall back with a stronger system moving through the southeast from Friday. I will more on that later this week and over the weekend as the model confidence is rather low on that.

Putting it all together.

Rainfall for the next 4 days - Valid Wednesday 7th of July 2021.

Clearly the confidence on rainfall coverage has improved during the past day but the rainfall within the pink zone is highly variable on where thunderstorms form. Some areas could exceed 40mm here and some could not see 25mm, but the coverage of rainfall should be moderate within this zone. Now the coastal areas where the low passes over and deepens offshore from, will see a period of strong winds and widespread showers Friday into Saturday. Drier weather later Saturday as the winds turn southerly along the coast and the showers move parallel to the region.

Most other regions in the state should see dry weather with patchy rainfall around this region of 1-3mm likely but not much getting further south than about Orange to Sydney.

Lets have a look at the coming systems that will impact the southern parts next week and the westerly wind belt will dominate the southern half of the nation with a fast flow pattern setting up, with frequent frontal weather pushing through.

Significant moisture off WA will be drawn into the westerly wind belt, with the concentration of that still uncertain but certainly a good chance of seeing a few cloud bands in the mix next week with the frontal weather raging through the southern states.

Simulated IR Satellite - Valid for the next 10 days. Wednesday 7th of July 2021.

Note the cloud bands are starting to increase in frequency riding along the northern periphery of the cold and wintry airmass over southern Australia, once again this situation may continue to evolve and increase the chance of inland rainfall returning for NSW, SA and northern VIC. Possibly falls getting into southern QLD if a system develops with enough northward motion.

Rainfall for the next 10 days - Valid Wednesday 7th of July 2021.

A closer look at the southern and central inland of NSW with eastern VIC and you can see the westerly wind regime rainfall is back with those on and west of the divide in NSW and along ranges in VIC will bring moderate falls over a number of fronts, I am expecting this rainfall to increase. Rainfall over the Sydney region northwards is dependent on low pressure movement this Friday into Saturday but then the westerly winds dry out the entire coastline shielded by the Great Dividing Range.

Rainfall for the next 10 days - Valid Wednesday 7th of July 2021.

Rainfall will be plentiful over the northern inland of NSW and southern QLD initially as stated, the focus then shifts to the south along the dividing range and through southern VIC and southern SA with frontal weather increasing next week. The front Tuesday and the front that follows during Thursday and Friday hold the better potential for rainfall returning through these regions with cloud bands and frontal weather moving through. That setup will dry the coast out.

The weather next week is hinged off whether the precipitable water/moisture can be drawn into frontal weather. This chart will be valuable to measure the risk of rainfall increasing or decreasing during the coming week to two weeks.

00Z GFS Precipitable Water Anomalies - Next 2 weeks - Valid Wednesday 7th of July 2021.

Note the moisture persisting over northwest Australia, but can the jet stream tilt more northwest southeast or will it maintain an east west trajectory? If the wind flow can turn northwesterly then more moisture will be drawn into frontal weather and I am still leaning to that outcome being achieved at least once during the coming fortnight.

More weather information on this a little later tonight.

78 views2 comments