The average conditions are set to continue this week over SA, there is follow up rainfall on the way for much of the southern coastal SA, some of that could be moderate. Over the inland areas north of the YP through to about Mildura and Renmark, rainfall gradient turns light and essentially drier weather as you head up the Stuart Highway to the NT.
There are three frontal boundaries in the forecast period and one weakening low pressure system, all of which will bring rainfall to the southern third of the state. Some of the falls could be surprising with the low pressure system moving in from WA and with the system arriving on Friday into the weekend. Models are not set in stone on the rainfall coverage and intensity with the low as you will see below.
The weekend system is quite dramatic on some modelling, other models are less enthusiastic, so again drawing charts for what one location can expect over a 7 day period down to the mm and the forecast max and min within this time, but that's the beauty of this fast flow pattern.
Lets have a look at the modelling.
00Z GFS Surface Pressure Pattern for the coming 16 days
A vigorous westerly flow will retreat a little further south this week, and the wave coming through on Monday night into Tuesday will bring lighter rainfall but likely peaking to the east of the region through VIC and southern NSW. A low pressure system coming out of WA will be stalled by the system moving over the east Tuesday but eventually sweeps in from the west Wednesday bringing areas of rainfall to the west and that spreads to the YP and the inland areas with NSW and VIC during Thursday as it becomes absorbed into a westerly flow. Then the next system approaches Friday with a chance of a damaging wind event and rain band pushing through with a messy showery weekend on the cards, again favouring coastal areas. Another set of fronts approaches next week with the pattern stubborn and not changing much.
00z GFS Rainfall for the coming 10 days
Again coastal areas doing best over the YP and points east, but some reasonable falls also getting into the inland adjacent to the coast especially with the low as that passes over. That rainfall could be heavier than what is being advertised here, so stay tuned to that. Then we watch the weather out of the west, if this model is right, I am going to increase rainfall totals through the week but for now I am siding with the truth laying somewhere between GFS and Euro as you can see. The weather still active next week with more moisture lingering over WA.
00z Euro Surface Pressure Pattern for the coming 10 days
The Euro surface pattern is similar to GFS but the intensity and magnitude of the westerly flow is not as intensive so that means you will see lighter falls with the Euro model. However it has got the low pressure system coming through SA with a lot more moisture which is encouraging, so 10-20mm could fall in some parts of the YP through Adelaide and into the Riverlands with that feature - something to watch. Then the next wave of cold fronts can be seen drifting in from the west and there is moisture over the inland which could bring significant cloud and rainfall early the following week. So the rainfall will roll around a lot during the coming few days. So you can have all your weather apps, throw them out and stick with the analysis as the computers just cannot render those small scale changes.
00z Euro Rainfall for the coming 10 days
Rainfall from the Euro model is largely lighter for the first and third system but has more with the low moving out of WA which is good to see for the Ag areas, but I will have more on that tomorrow when more data comes in and we can get the system surging through the southeast off the board. The next wave of weather coming out of WA later in the period could bring more rainfall and there are fast moving fronts that look to be moving further north from where they are now, again will track the SAM over the coming few days and see if that is heading into a negative phase to end the month. That would mean fronts would link into the moisture much easier and bring up rainfall totals for the end of the month and into August. So plenty on.
Rainfall for the coming 10 days.
Rainfall fairly uniform and related to the westerly wind belt which is seasonal for this time of year. The elevated PW values will mean some of that rainfall will move inland a bit more easily than normal, but falls over the course of at least 3 events will be light over these inland areas. For the Ag areas we have been tracking follow up moderate falls with these fronts especially the low that weakens on Wednesday into Thursday and then the weekend feature in about 6 days. So they are the systems to watch. The front and upper trough coming through tomorrow night through Tuesday will bring light falls but mainly east of the YP, but keep watching the satellite tomorrow as there is PW values elevated ahead of that feature and it could surprise.
This time of year the models do struggle with higher levels of PW in the atmosphere when there is colder air and cut off low pressure etc, so the rainfall forecasts will change a lot on the model data so keep that in mind. The rainfall forecasts carry a low confidence strap at this time