An upper low and surface low will begin to lift out of WA during Tuesday towards the east and begin to weaken a tad on the approach to SA.
The rain has been widespread around the low, but the moisture is now starting to decouple from the centre of circulation, the upper level winds taking the moisture as cloud into SA today and the eastern states on Tuesday with no rainfall expected.
However, moisture is likely to build on the northern flank of the system as it moves into the east and will see another rain band develop in response to this over central and eastern SA and the western parts of QLD, NSW and northern VIC.
National Satellite - Monday 31st May 2021.
Showing that moisture starting to become decoupled from the low pressure system south of WA. This will see the cloud thin out and become fair weather under a strong upper ridge over SA and the eastern inland.
Precipitable Water Values for the coming 5 days - GFS 18z run valid Monday May 31st 2021.
Can clearly see the dry air that is currently in place over the eastern inland with the high pressure in full control. The rain should thin out under most of this cloud during Monday, but another pulse of moisture will feed down the spine of the trough moving through SA during Tuesday into Wednesday with a new cloud band developing over SA, and western QLD and NSW. This is where the next rain band will form.
The moisture is likely to sufficient with a sharpening upper trough and low passing through the eastern inland to support widespread rain and a few storms over mainly NSW and southern QLD. Some parts of southern NSW and northern VIC may miss out in this wave of low pressure, but confidence is still low on rainfall distribution.
Rainfall for the next 5 days - New South Wales and Victoria with eastern SA. Valid Monday May 31st 2021.
The rainfall coverage will be dictated by where the thunderstorms develop initially through western NSW and QLD and how that rides southeast through the central and eastern parts of NSW and southern QLD. Lighter falls generally will be the rule the further south you are.
The sharpening upper trough over NSW may form into a low on the Mid North Coast or Northern Rivers during Wednesday night into Thursday which could increase rainfall coverage over the northeastern third of NSW and perhaps southeast QLD on the northern flank and warmer sector of the system. The system is likely moving at pace thanks to the kick along by a shortwave over southeast Australia so severe weather is unlikely to form as the low will push off steadily from the coast at this time.
GFS 18z run for surface pressure pattern and wind profile for the coming 5 days - Valid May 31st 2021
Note the surface circulation washing out over SA and western NSW (still an upper component) but then resurfaces just offshore the NSW coast as it is captured by a cold front over the southeast. Sadly if the cold front was in phase with the upper low, then more rainfall would be possible for VIC, SA and all of NSW in that scenario, but again you can see the impact of the systems being out of phase and rainfall being placed further north through NSW and into QLD.
The system lifts out by the end of the week and we turn back to dry weather for the inland, with the return of severe frosts and another possible freeze over the GDR through the weekend. That will continue the run of severe frosts and below average overnight minima.
However there is a significant signal for rainfall to return to the inland of southern QLD, NSW and into the southeast states with another significant low pressure system forming over the east and south. Model madness continues on that event but there is something lurking out there, which may bring follow up falls to parts of the east next week.
Right now there is no skill in giving specifics, but this could be in line with the climate outlook and analysis made here in recent weeks of the end of May ending damp and cold for the east and June starting out active over southern and eastern Australia, while the west takes a break after a wet spell.
Euro Upper flow pattern at 500mb/18000ft 12z run - Valid Monday May 31st 2021.
Deep upper low cut off from the westerly wind regime, with a high amplitude pattern over Australia with riding on the east coast and west coast cradling this feature. This system has the ability to move slowly over the east bringing a spell of wet and cold weather to widespread areas if it was to verify.
Euro 12z rainfall spread for the coming 10 days - Valid Monday May 31st 2021.
Widespread falls from 2 events brings up rainfall chances for the east with some areas under this scenario, receiving a months worth of rainfall in a week, again if this was to verify.
The forecast outlook beyond the weekend has a low confidence forecast with model madness likely to continue, so for now I will focus on the next 5 days as that will hold some reasonable rainfall possibilities for many inland areas delivering mixed blessings to those on the land.
Want more tailored weather information? Email me at firstname.lastname@example.org for further details on packages available.