A strong cold front is now starting to interact with the moisture and warmer airmass over NSW and scattered showers and thunderstorms which have been ongoing overnight through the northern inland and across the southwest are now moving east.
It will be mild and sunny for some in the east before the rainfall arrives this afternoon.
Satellite Imagery shows the battle of the airmasses underway and in response showers and storms are increasing over NSW this morning. Also showers developing further north over QLD in the middle layers but not much rain in it yet. A cold pool of air which is the fuel to this rain band increasing is currently over SA, this will move east into NSW this afternoon and evening and widespread rain will form in response to it. Otherwise clear skies elsewhere.
Showers and storms are developing in QLD, NSW and throughout VIC. Colder air with showers throughout the southeast of SA with hail and thunder.
The current state of play this morning, basically showing you the elements coming together to produce that rainfall.
Once the rainfall arrives it will be slow to ease over the eastern parts of NSW and the ACT. Some moderate to heavy falls are possible as the front moves through. It is expected that a low pressure system will form along the front as it moves through towards the east this evening.
We have got an active day of thunderstorms which is currently already underway throughout the eastern inland and throughout the southeast of SA.
Damaging winds are a chance today throughout the state with thunderstorms driving the main risk over the inland but scattered and random distribution of this, though an organised line of storms may form over the GDR in the warm sector. Squalls are possible this morning over Alpine areas over 100km/h with the thermal gradient and pressure gradient very tight.
A low pressure system forming offshore the NSW coast will send strong to gale force southerly flow during Tuesday afternoon easing Wednesday.
Small hail risk will start to move into the state later today and be with us on Tuesday. Some of the stronger storms could produce hail about the southern inland and southwest of the state plus a lower risk over the GDR in the north.
Snowfalls are possible throughout the GDR above 800m on Tuesday, this is due to the cold pool coming throughout the southeast inland. The snow should struggle to settle with warm days leading to the ground temperatures being quite warm so it should be low impact.
I would also suggest that flooding may be reintroduced for some river systems after this rainfall, just minor flooding for some tributaries west of the divide and flash flooding possible along the east coast which I will update later today. This can now be updated to Monday and Tuesday.
Raised dust may be an issue again throughout today but more likely to stay back through SA. The risk will ease this afternoon.
Heavy rainfall will persist into Tuesday, with localised flash flooding and damaging winds possible about the coastal areas, a more precise location is likely to be drawn later today as mentioned and the severe weather charts updated this morning.
Showers are expected to continue along the coast in southerly winds as the low continues to move slowly east. The weather drying out over the inland with partly sunny skies returning with high pressure edging in over the inland. There may be a wrap around trough that could bring another belt of rain up the NSW coast and adjacent inland Thursday before the influence of the low clears east.
We will see a general drying trend statewide for Thursday and then Friday warm and sunny. The weekend is expected to see the next change roll in from the west and this one could also bring another rain band throughout the state with again the details to be refined as we get closer.
There is a lot of rainfall on some modeling and not so much on others so it is best to take it one system at a time, with the focus of what is happening in the next 3 days most important.
Lets take a look
12Z GFS Surface Pressure Pattern for the coming 16 days
A strong cold front is passing through the east and brings the most dynamic weather throughout the nation over the coming days, elsewhere it is settled and seasonal though cooler air is filtering north throughout the nation. The weather is expected to settle over SA and VIC during the coming 24 hours with the weather expected to turn gusty and cold over the NSW coast with a low forming offshore. This may bring a period of severe weather, but also act to dry out the eastern inland with a chance of colder than average weather moving through NSW and QLD with frost risks redeveloping mid to late week. Out west, the next set of cold fronts are expected to roll through with a gusty northwest flow ahead of this, bringing up temperatures for the region, ahead of rain and a milder change Thursday. That system also looking to cut off into a low pressure system as it heads towards SA and brings the chance of rainfall back into the weekend. This system may help to draw moisture in over the eastern inland with widespread rainfall from QLD through NSW into VIC again, might piggy back SA. Another system then lurks next week with further areas of rain. Drier weather over the north and northwest with humidity increasing.
12z GFS Rainfall for the coming 16 days
Rainfall as you can see quite productive during the next 48hrs and that focus will slowly move towards the east coast by mid week. The inland should dry out, and essentially the remainder of the nation is dry away from the southeast coast until later this week. The next fronts will come through WA mid week and approach SA later Friday and then into the southeast by the weekend, tapping into the moisture that is redeveloping over the nation following the colder drier airmass that is surging north over the coming days. The dry air does not look to last as long, which is why we are seeing the rainfall chances increase now in the short to medium term which is anticipated.
12z GFS Precipitable Water Anomalies next 16 days
The PW water values following the low developing off the NSW coast is expected to turn drier nationwide but now this model says it is not lasting that long, so that will see rainfall chances return throughout the eastern and northern parts of the nation from the weekend, in advance of a weakening front and low pressure system approaching from WA. The west should see relatively normal PW values but the tropics may become humid and this could spread through to NW Australia, in a position for systems to pick this moisture up and pass it through the south and east into September. So this has been a change in the modelling during the past 24 hours.
12z Euro Surface Pressure Pattern for the coming 10 days
Pressure pattern largely unchanged from last night, and still suggests the most robust weather will be connected to the events over the south and east during the next 3 days or so. Then the frontal weather returns over WA, this may help to push a high east, which then knocks the low pressure system out to NZ. The quicker this happens, the more likely we are to see rainfall spread from west to east over the nation, bringing follow up rainfall chances for SA, NSW, VIC and QLD. Now the Euro does not see what GFS does, however that does not mean it is impossible. The model does see moisture, but cannot connect it together. But the charts are becoming more active.
12z Euro Rainfall for the coming 10 days
Rainfall very similar from last night. The weather is most active in the short term over the east, mid week over the west, that weather from the west will then come through SA to the southeast states from the weekend with the next chance of rainfall but the moisture that is in place is out of phase where GFS is in phase hence more rainfall.
12z Euro Precipitable Water Values next 10 days
The weather dominated by the amount of moisture available it seems and whether it can be in phase with the cold fronts and low pressure systems that are passing from west to east in the medium term. How the moisture is reintroduced, where it is reintroduced and how quickly that occurs will determine how much rainfall is about this weekend, so that is the difference between GFS and Euro this morning.
Rainfall for the next 10 days
There is plenty of rainfall in the short term with a drop in temperatures for the south and east and we are already seeing this develop during the morning. The rain most extensive from this afternoon and evening with a cold rain during Tuesday. The rain contracts to the east coast on Wednesday with the inland drying out with partly sunny skies. More rainfall is possible later this week into the weekend with some modelling suggesting heavy falls, others suggesting not as heavy rainfall, but one to watch.
I will have a look at the medium term again this morning as there are more weather events into the future that need to be looked at, as they could also bring some heavy rainfall.