A warm night ahead of that rainfall as it spreads east through the state tonight into Wednesday. The falls over the west mainly less than 5mm with the airmass at the surface dry despite the upper levels quite moist, hence the cloud cover. The front is also somewhat removed from the moisture surging southeast so that lighter rainfall signature should continue further east.
Note the moisture increasing in the upper atmosphere through SA hence the high and middle level cloud but the lower levels is quite dry so no rainfall falling from it. The main rainfall sits back through eastern WA and that will approach overnight and allow a new rain band form over the west coast and then spread towards the EP, YP and Adelaide by dawn. Moderate falls now possible about the southern EP.
The front will bring a burst of showers to the EP, YP and Adelaide from before dawn and clear by afternoon. A few showers looks to follow Thursday and now Friday for coastal areas east of Port Lincoln. But the inland should turn dry and mild.
The weekend, settled at this stage with a warmer northeast to northerly flow developing. Then we have another system rolling through WA on Saturday, it is now sitting further north tonight and cuts off into a low pressure system, expected to be carried through the southeast inland next week.
The forecast beyond Sunday carries a low confidence strap at the moment only due to the inconsistency on the impact of that low pressure system moving eastwards. This morning it was much more dynamic with rainfall developing from this time next week, tonight not so much. But this will continue to chop and change.
More rainfall opportunities are expected towards the end of the month too.
00Z GFS Surface Pressure Pattern for the coming 16 days
The pattern for the coming few days is still locked in from this morning, no real change in the passage of frontal weather over the south, nor the change in the cooler weather spreading through the southern states. We will see the west clear out later this week with high pressure moving in. In the east, a boundary may form over the NSW/QLD border with the widespread showers moving inland, thanks to the approach of a trough. That trough will pass through WA on Saturday and race east to be over the eastern inland during early next week, providing more support for the weather to turn showery. The medium term still offers widespread rainfall as you can see the in the accumulation below for mid month.
00z GFS Rainfall for the coming 16 days
Rainfall moderate along the front across the southern SA coast especially about the EP and possibly the YP and KI regions then into the southeast but will monitor, lighter falls now for Adelaide and points north and east but again this could chop and change overnight, depending on how the moisture behaves in response to the front rolling through. Then dry weather following clearing showers along the coast. Next week another trough approaches and from that point on the forecast is low confidence.
00z GFS Precipitable Water Anomalies next 16 days
The PW values largely unchanged in the short term and you can see that verifying in real time looking at the satellite imagery. There is a lot of moisture coming into NSW from the north as well via a easterly flow over QLD which has transported a parcel of deeper moisture through the inland, that moisture expected to link up with the cold front to see a band of rain developing along the front as it passes through the east. Then we watch the moisture build next week, via easterly winds and a boundary over the QLD/NSW border, over the tropics which will surge south and southeast via the upper level winds and another plume of moisture coming into the tropics from the east via the trade winds. Where this moisture is picked up by the low pressure remains to be seen.
00z Euro Surface Pressure Pattern for the coming 10 days
The pattern for the coming 5 days in good agreement with most global models so that makes the first half of the forecast fairly easy. The second half of the short term period below is volatile and hard to pin down the impacts of the moisture and the low pressure coming through the southern parts of the nation and that will continue to be the case for the next few days.
00z Euro Rainfall for the coming 10 days
Rainfall most widespread through the coming day with the front passing through the southeast states with a burst of showers and some thunder. The moderate falls reserved for southeast NSW and the southern parts of SA with the front interacting with deeper moisture. Dry weather for most this weekend ahead of another week of low confidence forecasting. We track that upper feature over SA this time next week, it offers a decent chance of the next rainfall event. But the specifics are too hard to pin down at this time, but you can see the difference between GFS and Euro tonight.
00z Euro Precipitable Water Values next 10 days
The PW values again from run to run are all over the shop in the medium term making it very tricky to find any consistency, but the ensemble data is more settled and show moisture increasing through northern and eastern parts of the nation during the middle of the month. So while you are looking at all your weather apps saying nothing, they don't pull ALL the data that is available out there. So the forecast while it looks benign on the Euro, there are signals in the broader data sets that suggest otherwise. For now there is that first system to watch this time next week which may offer rainfall from SA through VIC and NSW after bringing showers this weekend to the west coast.
Rainfall for the next 10 days
The most widespread rainfall is expected during the coming 36hrs as a front moves through. Then dry weather from Friday onwards to about next Tuesday, with high pressure dominating. From that point as mentioned there are systems wafting around but again very hard to be more specific at this time, but there will be some chance of rainfall returning from mid next week for large parts of the nation including parts of SA.
More weather details to come.