A very quick look at the low coming from the Indian Ocean next week with moisture in toe. This has the chance to bring widespread follow up rainfall to the SWLD of WA but what about further east?
Lets look at the PW values and the system moving across.
GFS 18z PW Values - Next 6 days
Good supply of moisture coming into WA but notice how the southwesterly surge early in the week interrupts its movement east, if that front was not coming through early in the week, then more rainfall would be experienced throughout southern and eastern Australia. It does somewhat stay in tact and comes through with the low mid week with light to moderate rainfall for SA into western NSW.
Euro 12z PW Values - Next 10 days
Very similar in it's approach with deep layer of moisture coming in on the westerly wind regime through WA. That weakening low and moisture will make it in mid week over SA into NSW. Then that major weather system links up with the moisture with a large rain band developing in response to that feature for southern and southeastern Australia with again a severe weather look to it. But take note, another moisture plume at the end of the sequence right behind that system resolving over the southeast ready to bring more rain into WA.
Euro 18z Surface Pressure Pattern - Next 10 days
Note the systems and the moisture and cross check with the above to see how the pattern interacts with the moisture coming out of the northwest.
Model Spread - Moisture and the low track - Tuesday 20th of July through Thursday 22nd of July 2021.
More on this later today - but there is the hope of some follow up next week for areas of WA, SA, NSW, VIC and TAS. This is the first low and not the second event that follow this time next week.