NSW - WARMEST WEATHER IN MONTHS ON THE WAY - THEN RAIN

The weather is in the process of warming up with a good supply of sunshine for Wednesday and Thursday, that is ahead of a strong cold front passing through, lifting moisture as discussed into areas of rainfall. Some of that could be heavy ahead of a colder change passing through on the weekend.


Then the medium term provides some interesting scenarios.


Latest details on the week ahead in the vlog.

Rainfall for the coming 10 days

The rainfall is still connected to the system coming through later in the week, expectations are the further east and south you are in the state, the better the rainfall coverage will be. However the timing and depth of the system will become clearer as we get towards Thursday as the models feed real time data back into the models and so expect the forecasts to change a little more. The wild card system is the second feature sitting over the eastern inland next week which would be quite possible if the SAM turns positive which the models have now started to react to - so will watch closely.

00z Euro Surface Pressure Pattern for the coming 10 days

The pressure pattern remains unchanged in the short term with high pressure dominating the east and sending in that very warm airmass. We then watch the strong cold front passing over the southwest of WA tomorrow and track that through the Bight Thursday and then into SA Friday an VIC through Friday night into Saturday and then into NSW Saturday with a few heavy falls along the journey from VIC into southern NSW. The band of rain extending back over the outback as well with the colder air surging north. Then a large high pushes in and noses out the colder air surging over the east out to the Tasman Sea, stopping the formation of follow up rainfall next week over QLD. The rain band likely under this scenario exits with the cold front, and I would be cautioning you to this outcome with a positive SAM phase possibly in play, this could see rainfall return to the east coast of NSW and QLD and possibly hang up the rain event over the east next week. For the remainder, once the front is through high pressure keeps you dry and cooler. The tropics see the odd shower and storm this week before a return to dry air.

00z Euro Rainfall for the coming 10 days

Rainfall comes in with a trough later in this week over the southern and western districts, at this stage the models are mixed in rainfall distribution with falls moderate to heavy over the far south and southeast west of the divide along the VIC border. But on the GFS you can see more widespread falls passing through, the trough slower and seeing a cold surge invigorating the rainfall once again over the northeastern third of the state thanks to a strong onshore southeasterly combining with colder air to produce that event. With a positive SAM phase likely to develop, rainfall over the east may persist next week bordering with QLD while the southern 2/3rds of the state west of the divide will be dry and cooler than normal. So inland areas, once the rain moves through it will turn dry and cool.

00z Euro Precipitable Water Values next 10 days

The moisture over QLD is drawn west over the tropics and part of the moisture is drawn south into the cold front passing over the southeast and east. The moisture coming in with the front from WA is modest and sufficient for a rain band to form during tomorrow. The moisture will also follow the front but for SA the lifting mechanism to bring rainfall falls to the southeast as feared last week as one of the options due to the Tasman high. Then the trough over SA gets new life over the eastern states, invigorated by the deeper moisture layer leading to widespread rainfall reforming on the boundary as it moves throughout the southeast and eastern inland. Dry air likely to surge through following the front with a colder airmass to sweep the moisture north and east. The tropics will see a moisture increase mid to late week ahead of drier air surging north next week, perhaps the last dry surge of the season.

Temperatures are expected to be well above average as well through this period, but the colder weather next week is still very much on the table and this volatility in the high amplitude pattern will continue for a number of days on the models. So look for trends!

The SAM being in a positive phase may hold the clue as to why the rainfall bias is shifting over eastern inland portions of the nation and so will keep watching this trend and I would not be surprised to see that major rainfall event that has been forecast by some modelling in recent days to return to charts in the next few days for next week. Especially for QLD and northern NSW. That would leave dry weather developing for southern parts of the nation under such indications, with high pressure in place.

I will have a look at the models in greater detail later this evening pending the rainfall event later this week into the weekend.


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