NSW - WARMING UP FRIDAY WITH THE CHANCE OF RAINFALL INCREASING THIS WEEKEND.

The weather is expected to warm up on Friday after a cold night on the way with the chance of severe frosts for large parts of the east as another ridge passes through. The frost not long lived but could cause a few problems for those tender crops.


Frost Forecast for Friday Morning - Thursday 29th of July 2021.

Come Friday afternoon, the frost will be a thing of the past with the a warm northwest to northerly flow developing, that bringing in that warmer and hotter airmass which I discussed in this mornings update. That is still continuing to be the trend with temperatures up to 10C above average through parts of the state, especially in the north.


The warmer air will modify as it heads further south, meaning that the weather will be milder further south but nowhere near the well above average values further north.


Saturday temperatures are expected to be well above the average with a long fetch northwest gale developing.


Temperature Anomalies Saturday and Sunday

This sets up the clash of the airmasses leading to more robust shower and storm development. So this will be the feature to watch during the next 24hrs on the charts, where does the storm and shower development initiate? Will it be over SA or further east over VIC or NSW?


The first front will whip through SA during Saturday and the eastern states from Saturday afternoon, VIC first and then into southern NSW during Saturday night. Showers developing with the front over SA and western VIC, with the chance of a storm then we have showers increasing to areas of rain for eastern VIC and southeast NSW. Some moderate falls are possible.


The battle ground where the hot air and the cold air fights it out, is where the rainfall will likely break out during Saturday.

Then the front should stall out as a trough with the moisture through NSW during Sunday, with areas of cloud, patchy rainfall. Warm to the north of the trough/front in the state and cooler to the south.


Another front will race in behind that system during Monday over the southeast, and help to lift the first trough and moisture plume north and see that patchy rainfall increase for northern inland NSW and into the Northern Tablelands and over southern QLD.


Next week the weather begins to clear out with high pressure developing from the west and the frontal weather with the westerly winds retreating southwards.


Lets look at modelling.


00Z GFS Surface Pressure Pattern for the coming 16 days

The modelling is now starting to shit in the medium term. First, we have got that fast flow pattern that is expected to continue for the next 5 days. But that is likely to ease over the coming week, with clearance of that westerly wind regime to the south by this time next week with high pressure digging in from the north and west. As the high moves in, note the moisture is likely to build in easterly winds with showers along the coast returning, and more moisture coming through QLD. Now this is the first time the modelling has really gone hard on this so I will take this as a signal and won't draw it in on my products, but again this is the sign things are about to shift from the westerly wind profile for southern and eastern Australia.

00z GFS Rainfall for the coming 10 days

The wettest period of the southeast states is over the coming 5-7 days with the systems to come during the next week connected to the final long wave passing through the region. The weather will greatly improve from this time next week with more settled skies, cold nights and sunny days inland, along the coast there could still be a rogue shower. It does appear this will be a chance of some of the driest weather in about 6 weeks for the southeast states.

00z GFS Precipitable Water Anomalies for the coming 16 days

This product again shows the shift in the conditions after we get through the last of the frontal weather. The nation begins to be dominated by high pressure as it digs into the southern states. The more settled weather expected from Thursday for a number of days next week. As that happens, the whole pattern resets and we see easterly winds strengthen over the north and east and finally gives the eastern inland a chance to see moisture return, coastal showers return to the east coast, giving the south a chance to dry out. Then out west we watch the moisture surging southeast into frontal weather approaching next weekend which may bring a separate rainfall event to the west. Another rainfall event may develop over the northeast with a deeper moisture plume over much of QLD. That is the second time this model has shown this today. It is a trend not a forecast, but something that is gaining traction.

This is the feature to watch mid month

00z Euro Surface Pressure Pattern for the coming 10 days

The Euro is like the GFS tonight with moisture likely to reset under the new high pressure system next week. We can see a good supply of moisture coming in ahead of frontal weather over the southern and eastern states over the coming few days, leading to once again light to moderate follow up rainfall. The northern inland of NSW and southern QLD could surprise during Sunday and Monday as an upper trough deepens with the second system surging northeast bringing a colder southwest shift to the southeast state. If that happens then we will see more rainfall than what is being forecast for the eastern inland. The pattern looks more impressive for rainfall to return to the inland of WA and QLD by mid-month. On current guide that seems a fair assessment.

00z Euro Rainfall for the coming 10 days

The rainfall is largely unchanged for the coming 5 days with most of the rainfall to occur over the southeast during the next 5 days or so, some of that moving into inland NSW and southern QLD. It is all out the door by mid next week as a ridge builds in from the west with settled skies, cold nights and sunny mild days. The pattern starts to turn warmer and drier through next weekend and by then we will likely be talking about what is the next lot of weather to watch over mid month, which looks like there is a lot of rainfall for some locations in eastern Australia.

00z Euro Precipitable Water Anomalies for the coming 10 days

The PW Values really paint the picture just like GFS with the high pressure system coming in and resetting the moisture distribution, more of that moisture surging north of the nation and then being drawn south over QLD and through WA. There is the potential for rainfall events to start impacting the nation from next weekend. That is a little earlier than GFS.

We will watch these two areas in the short term, with the GFS event in the medium term a week later.

Rainfall for the next 10 days

Rainfall is largely unchanged from this morning with the modelling nearly the same as this morning. For northern areas of NSW your numbers may increase as we get closer to the Monday event as the trough sharpens and interacts with moisture and for pockets of the southern and southeast inland bordering VIC with the feature coming through on Saturday. Conditions ease this time next week with a dry few days.

More weather details to come.

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