SA - A FEW SHOWERS ABOUT THE SOUTHEAST, OTHERWISE DRY FOR MOST OF THIS WEEK.

There is also the chance of follow up rainfall developing in the medium term with moisture being drawn southeast and south via the upper level winds. The weather is expected to become more active through the latter part of the month.


Ahead of that, the weather largely dry and settled for inland areas as we track the ridge through from west to east with a warmer airmass just to the north of the state expected to drift southeast through Thursday and Friday ahead of the weakening front coming out of WA.


That front may trigger showers for parts of the state with some thunder possible about coastal areas of the EP and YP. But the weather begins to become interesting from this time next weekend into the following week. That will dominate the weather forecasts this week to see how this stacks up in reality as there will be some wild projections in the modelling.

Again the more interesting weather feature is the one sitting out in the medium term just on the other side of the weekend. As you can see all the ingredients are there for widespread rainfall.

Lets get into it.


00Z GFS Surface Pressure Pattern for the coming 16 days

The pressure pattern is quiet this week, that is well documented. The first change coming through the southern parts of the nation hits WA during Wednesday and slides, weakens on approach to the southeast states. That will introduce warmer weather for southern areas and then showers developing for SA, VIC and TAS, perhaps southern NSW but otherwise the inland areas remain dry. Next week the stronger system that comes through southern WA moves over SA and clashes with the hot airmass driven south through the northwest flow, interacting with moisture over the eastern inland with a larger area of rainfall and thunderstorms developing. That could bring the heaviest rainfall of the month for SA, VIC, NSW, QLD and TAS. This system may take a while to move through. Fine weather over northwest and western parts of the nation while the east is drenched under this guidance. The tropics turning humid and unsettled during the next week.

00z GFS Rainfall for the coming 16 days

Rainfall fairly light on for the week across the nation, with only coastal areas of the southeast and the eastern parts of QLD expected to see any rainfall this week. Then a change rolling through WA, will introduce showers and perhaps some moderate falls for the southwest of WA. The first front will weaken as it passes through to the southeast states bringing showers to southern SA and into VIC and TAS. A few light showers are possible for southern NSW later this week. A stronger system coming through WA Thursday will kick along the showery weather for the weekend over the southeast states with some moderate falls for TAS and southwest VIC. Showers may creep into southern NSW Saturday into Sunday. Then the stronger feature will pass through the southern and eastern states from early the following week with moderate to heavy falls possible in that configuration for pockets of southern and eastern Australia. We will see it chop and change so this will be the area to watch. When the east turns wet, the east will likely be drier. The north of the nation will see an increase in humidity

00z GFS Precipitable Water Anomalies next 16 days

The PW anomalies again painting the picture of the drier air under high pressure being overrun by the moisture that builds over northern and eastern Australia in the persistence of easterly winds. Those easterly winds will become more frequent as we track through spring and into the summer, so the importance of them for areas of the east are a given, but for central areas of the nation too, very important. The system from the west runs into the moisture drawn through eastern Australia seeing larger scale rainfall break out. The anomalies suggest that even though modelling is showing moderate rainfall, there could be some heavier falls than what is being indicated.

00z Euro Surface Pressure Pattern for the coming 10 days

The weather is expected as you know quiet for much of the nation. Lets take a look at the middle of the week and the first front is passing through WA bringing a burst of moderate showers, high pressure over the central and eastern parts leading to clearing skies over the southeast and a persistence of clearer weather for the east. Warmer temperatures are expected to build through the outlook period as a northwest flow gets going for the southeast states ahead of that front. The first front may bring more rainfall if Euro is right to the southeast and southern states. A follow up system, similar in scale to GFS, looks set to pounce on the southeast early the following week, but is drier than GFS. So there are some divergence on where the moisture is getting involved with the frontal weather moving from west to east.

00z Euro Rainfall for the coming 10 days

Rainfall largely unchanged from this morning, but there has been an uptick in numbers for the southeast states Friday through Saturday. But the model is different to GFS for the medium term bringing less rainfall in that system the following week, so again there is divergence, but we are now as expected seeing more consistency for the medium term. Now we wait and see how the data holds in coming days.

00z Euro Precipitable Water Values next 10 days

You can see the moisture building in the easterly winds for the eastern parts of Australia with the onshore winds. Another shot of moisture coming in from the northwest via the jet stream may sneak in ahead of the front coming through WA mid to late week, that could provide more rainfall than what was forecast in this evening's forecast packages from the BoM. I will have another look at that tomorrow morning and introduce higher rainfall into rainfall forecasts into the latter part of the week. The moisture looks to be shoved out by the strong and gusty westerly change with a larger system the following week where you can see with the GFS, that model holds more moisture in place bringing up rainfall chances.

Rainfall for the next 10 days

There are a few showers about the southeast this evening with a weak front rolling through TAS and VIC. The main impact is a drop in temperatures and more cloud being drawn through to southern and southeast inland areas of the state, so not so bright to start the new week. Then we will dry out during the middle of the week as the high consolidates over the region, bringing brighter skies and northwest winds, temperatures are on the rise as we track through that high to the east. That will make room for the first front to pass through during Thursday afternoon with some rain and a thunderstorm. Then a stronger system will approach during the weekend and I suspect by this time next week will be staring down the barrel of a more dynamic weather event. For now the rainfall captures the average across the data sets tonight, BUT THIS FORECAST WILL CHANGE! So look at it as a trend and not an absolute. You will notice in your apps they will chop and change, there is no skill yet in specifics.


I will take a closer look at the medium term forecast with a deeper dive into the rainfall potential for the end of the month. The weather is expected to become wetter as we go through August and that looks to be fair on current trends. So more on that tomorrow. Tuesday the next Climate Update with a detailed look at the La Nina chances.


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