The charts that are going to provide insight this week will be the precipitable water charts with the surface pressure pattern. Looking at just the GFS model is going to give you ulcers if you are hanging out for rainfall over the eastern inland of Australia, with the model likely to chop and change over the coming 5-6 days as we wait for better data on the following;
1. How the southern ocean systems behave,
2. How much moisture is drawn through the eastern inland thanks to high pressure
3. How strong is the upper trough and front as they cross over eastern areas during next weekend.
This is not focusing on the coastal showers that will develop from Tuesday, that is going to impact coastal areas, and will fall in line within what one would expect during this time of year.
Lets compare the GFS model run to model run and you can see the differences in the placement of moisture on rainfall distribution.
GFS 18z run for Precipitable Water over the coming 2 weeks- Sunday 27th of June 2021.
Note the southward bias of the moisture later in the week into next weekend which is then overrun by a cold airmass with a trough and low lifting that moisture into widespread rainfall over QLD and NSW with many inland areas copping a drenching under this guide.
Rainfall for the 16 days - GFS (Using the 16 days of rainfall to illustrate the precipitable water being utiltised by the pressure pattern drawn out by the model this morning) You can clearly see if the moisture marries up with the trough and front moving through the southeast, it could be quite a productive event. This is no obsolete data but a great example IF it all comes together.
GFS 00z run for Precipitable Water over the coming 2 weeks- Sunday 27th of June 2021.
The latest guide from the model tonight shows the precipitable water values have retreated a little further north and east of this mornings run, meaning rainfall won't be as widespread through inland areas, if this model is to be believed.
Rainfall for the 16 days - GFS (Using the 16 days of rainfall to illustrate the precipitable water being utiltised by the pressure pattern drawn out by the model this evening) Widespread showers and scattered thunderstorms with a trough moving through the east later this week, doesn't quite link up with the full moisture profile, instead that occurs offshore with the system moving through quicker later in the weekend. This evening's run does have further rainfall developing in the day 10 range (refer to the National Weather Picture post for more).
Let's take it back a step and have a look at all the modelling this evening to see whether they all initiate the trough later this week over the east, to see if the GFS model in the medium term, actually has merit. Because the trough has to be in place to lift the moisture initially and then be invigorated by the front and cold air from the south and west after this. That will bring the widespread rain if it comes together in the right place.
Euro Rainfall next 10 days - Valid Sunday 27th of June 2021.
Rainfall modest, and confined mainly through QLD but the overall trend in the surface pattern is now supportive of a low forming over southeast Australia, holding up the trough so the rainfall totals could increase over northern and central NSW and much of QLD so will review this in the morning. But it is in agreement with GFS in terms of picking up the front but what it does after this is up in the air.
Korea Rainfall next 9 days - Valid Sunday 27th of June 2021.
Very similar to GFS in the spread of rainfall through the eastern inland with the trough riding through from the west and combining with some colder air, then onwards into the deeper moisture layer, lifting that into areas of rainfall and a few storms. Again the controlling factor for the speed of the trough through the eastern inland will be connected to whether the trough is kicked out by a trough (as per GFS) ending the rainfall quicker, or whether a low forms (as per Euro) and holds the trough in the region and bring a multi day rainfall event.
ICON Rainfall next 7 days - Valid Sunday 27th of June 2021.
You can see the spread of rainfall developing through the eastern inland over the latter part of the week into the weekend, though this model indicates the front and cold air will stay further south over VIC and TAS with that meaning light to moderate rainfall would be expected but clearing quickly.
ACCESS-G Rainfall next 10 days - Valid Sunday 27th of June 2021.
More of a convective look to the rainfall over eastern Australia with a trough triggering showers and thunderstorms in random scattered locations, but the colder air is not quite in sequence with the moisture and nor is the frontal passage. But it does come together offshore in the Coral and Tasman Sea, with large rainfall totals just offshore.
So there is a high degree of uncertainty in the forecast and this will continue to see rainfall and temperature forecasts to chop and change dramatically over the next few days if you live in QLD and NSW as a consequence. Also understand that if you are looking at yr.no and your town and you have rainfall tonight, you might have a very different look in the morning.
I will have more to say on this over the coming few days but rest assured there is more rainfall in the future, and with the SAM in a positive phase coming up this week, this is supportive of rainfall breaking out in this region of Australia.
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