SA - A WARM THURSDAY ON THE CARDS BUT THE RAINFALL RETURNS TO THE SOUTH FRIDAY.

A weakening cold front will move from WA through SA with a pre frontal trough attached expected to bring a broad area of cloud cover and the chance of patchy rainfall.


Satellite Imagery shows the dominance of high pressure with temperatures above average thanks to the good supply of sunshine in recent weeks over the inland and now a northwest flow aloft. The cold front that is set to bring the wet weather is still sitting west of Perth this afternoon and that passes over WA tomorrow and then into SA during Friday.

The surface based moisture is quite low so a lot of the rainfall that tries to fall from the mid layers will likely evaporate through the Nullabor.

Relative Humidity low over much of the inland at the surface, the values are higher in the east which will see more widespread cloud development and patchy rainfall when the weakening front arrives.

The moisture is being dragged in via the Indian Ocean but is elevated moisture and a lot of it will produce high and middle level cloud, the front is somewhat decoupled from the moisture and only assisting in dragging it through the southern parts of the nation. So lots of cloud, patchy rainfall Thursday night through Friday with 1-5mm the best of it for now.

Temperatures are the big talking point over the coming few days, but even after the front passes through, the temperatures are anticipated to remain fairly high over the weekend, especially inland where some locations could be into the low 30s until early next week.

Temperature anomalies this weekend.

Temperature anomalies this time next week.

So farmers and graziers be advised of a large drop in temperatures next week, with the chance of frost forming if the high can quickly race in and settle the weather down and bring clearer skies.


Lets have a look at the rest of the outlook and that major front early next week.


00Z GFS Surface Pressure Pattern for the coming 16 days

The pattern locked and loaded for a warm end to the working week over the eastern inland of Australia with cold fronts combining with a high pressure system over the east to bring a warm and dry airmass through much of SA, VIC, NSW and QLD. A front will pass through WA tomorrow bringing showers and storms and that front will then pass into the southeast states in a weakening phase. A stronger system passes through during Sunday into Monday, this front likely to bypass WA with it peaking over the southeast states. The weather turning cold and showery with even a band of rain possible for large parts of NSW as the system rolls over the GDR. A colder surge will then roll throughout the southern half of the nation. Another system then will try and form off the QLD coast as the cold southerly surge stalls through the region. The bulk of the rainfall is being shown to fall offshore QLD while the rest of the south turns dry and seasonal. Dry air surging through the NT clearing the humidity out briefly. Then you can see more weather systems emerging from the west for the remainder of the month, with more rainfall opportunities.

00z GFS Rainfall for the coming 16 days

Rainfall largely confined to the southern coastal areas for the coming 5 days and about FNQ. Then we are looking at a stronger system to extend the rainfall back through the inland as the colder drier air surges through the well above average warmth and modest moisture supply. Increasing signals for rainfall to return to the inland of NSW and some of this may creep into southern QLD. The west of the nation turns dry through mid next week then the troughs and low pressure starts to return bringing back rainfall and milder weather. The end of the month has further signals of rainfall developing towards September over large parts of the nation.

00z GFS Precipitable Water Anomalies next 16 days

The moisture profile over much of the nation is chopping and changing from run to run, you can see the impact of the moisture being more prevalent on the charts this evening, being picked up by organised areas of low pressure and this to create rain bands traversing the country. Remember this morning, the drier airmass was winning out, tonight, there is more moisture to work with. This again expresses the uncertainty.

00z Euro Surface Pressure Pattern for the coming 10 days

The pattern is largely unchanged from this morning and does look lean compared to GFS which takes it out to the medium term. The frontal weather is passing from west to east in the coming days and mainly impacting southern areas of the nation, we get that, well documented. Lets look at the next system and that seems to be moving through a little faster than the GFS but again this is different to this morning. The system peaking east of SA through VIC and southern NSW with the bulk of the rain. One things that the models agree on is the colder shift behind the front that will drop temperatures. Lets keep an eye on the southerly surge following the front over the east coast, we could see more widespread showers return to the NSW and QLD coasts.

00z Euro Rainfall for the coming 10 days

Rainfall unchanged from this morning for the southern states from WA through SA and into VIC and NSW. The only shift has been the dropping off of the rainfall away from the east coast of NSW and QLD, but that is likely to change with a colder air mass surging north into the warm humid air in the region, I suspect that rainfall chances will come up again for the eastern parts of QLD and NSW. Dry over much of the interior for now, which is against the longer term trends that were proposed 2 weeks ago so that has not verified.

00z Euro Precipitable Water Values next 10 days

The PW values continue to chop and change, tonight the Euro has more dry air than the GFS. That is in contrast to this morning. This is continuing to express the high level of uncertainty surrounding rainfall in the medium to longer term. But looking at the satellite picture offshore the NW of Australia, I would be leaning more towards GFS.

Rainfall for the next 10 days

Rainfall is largely confined to coastal areas still for the next 5-6 days with the frontal weather passing over the state with a modest supply of moisture over the northern flank of the long wave being pulled over the southern states. This will introduce patchy rainfall with light falls overnight tomorrow into Friday. There is the chance of some thunder, but not overwhelming thunderstorm activity. The better rainfall chances are for the southeast of the state as the stronger colder front pushes through late Sunday into Monday, but at this stage the bulk of the rainfall will be over VIC and southeast NSW with dry air surging through SA with light falls for now. More rainfall does exist beyond this period, but the confidence is low.


I will have the latest update on the medium term weather as that is sparking a lot of interest at the moment the atmosphere is starting to become more dynamic in the medium term. Rainfall events do exist beyond this period so will have more on that after the morning short term state based weather forecast.


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