A broad band of rainfall has begun to evolve with local thunderstorms today, that thunderstorm activity is expected to persist overnight with the areas of rain through the eastern half also expected increase in coverage.
Satellite shows the evolution of the heat clashing with the colder air and the deeper moisture being lifted into widespread rain and thunderstorm activity. Note the cold air field in SA and throughout VIC producing widespread showers throughout the southeast following the front.
Farmers and Graziers out on the land should now be experiencing that colder blast coming up from the south with that cold rainfall.
Two rain bands have formed and are likely to merge overnight with moderate to heavy falls developing.
Thunderstorms are rolling through the eastern inland thanks to the airmasses clashing this evening and these storms will progress eastwards tonight.
The rain areas will clear the west of the state with colder drier air surging north this evening, but scattered showers with hail about possible before that clears through from the west overnight.
Rainfall is expected to persist through Tuesday with heavy falls over the central and southern coast as a low forms on the front as it moves through during Tuesday. The low may bomb offshore and cause a period of gales as well. The inland is expected to remain dry with a frost risk developing for Wednesday morning.
Flood Watch continues as the rainfall becomes heavy tonight, multiple rivers on and west of the divide likely to see some rises over the coming 48hrs.
Damaging winds are a risk along the east coast as a low bombs offshore. Southerly gales of up to 100km/h possible with that low expected to form between Batemans Bay and Gosford. The low will slowly move off during Wednesday.
The weather for the state will clear by Thursday, another severe frost possible during the morning over inland areas but from that point we see seasonal weather, more sunshine expected and indeed that is the case for Friday.
We have another chance of warmer than normal weather Friday ahead of another system developing over the Bight. That may bring a humid northerly flow through the upper atmosphere with widespread rainfall developing for the eastern and southern inland of the nation. That remains to be a difficult system to forecast this far out but shows promise for areas that have missed out.
Below average temperatures mid week will help contribute to the colder nights. Colder air aloft leading to dry sunny weather.
Warmer weather developing this weekend ahead of a change with areas of rainfall also now likely to pass through the east, so the weather may not be as warm as what was forecast this morning, so something to keep in mind.
00Z GFS Surface Pressure Pattern for the coming 16 days
The major rainfall event is ongoing over the east. From mid week we will see the low pressure system that forms begin to move off to NZ and this will allow the high ridging in over WA and through SA to move further east, opening the door for frontal weather to pass in over the nations west. Rainfall will ease over the east and develop out west. The dry air should surge through the north clearing out the humidity for a period. Later in the week a front will approach SA but turn into a low pressure system before it slowly advances eastwards. Moisture is likely to be pulled south through QLD into NSW with a trough developing over the eastern inland, this could see widespread rainfall redevelop for the east with heavier falls for QLD with a trough hanging over the east coast. That rainfall could persist for a number of days. The rainfall lighter through SA and VIC but milder weather will make it feel spring like. Then we will track the low over the Bight through Tasmania, and weakening. Another front is likely to launch over WA through the early part of next week and that may bring yet another burst of rainfall to the east and south into early September.
00z GFS Rainfall for the coming 16 days
Rainfall heavy at times over the east with flood watches and severe weather possible. The weather over the remainder of the nation is likely to remain dry with a cooler airmass. The next lot of rainfall is expected out west during Thursday with moderate falls. That system will help to initially kick out the low off the east coast but then bring the low pressure from the west through to SA introducing follow up rainfall for the southern and eastern states. The rainfall for QLD could be quite heavy over the weekend into next week. The west will see another cold front during early next week and that will advance east once again.
00z GFS Precipitable Water Anomalies next 16 days
You can track the drier air coming in over the southern and eastern states with a cold southerly flow developing. That southerly flow is expected to sweep throughout large parts of the nation and flush the humidity out of the tropics mid to late week. Another surge of moisture will develop over parts of WA and this will run across the south of the nation with a low pressure system forming in the Bight. That low will also help to drag moisture from the northeast and north and filter through the eastern inland, feeding a trough over the weekend and next week. More moisture runs through the nations north and this may increase values over WA and then feed frontal weather passing over southern Australia.
00z Euro Surface Pressure Pattern for the coming 10 days
The pattern is largely unchanged from this morning. Euro is still suggesting 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 from mid week, 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 still does not see what GFS does, however that does not mean it is impossible. It does however have a much larger long wave sweeping in from WA later in the period which on this read would create quite a hefty rainfall event in the first week of September.
00z Euro Rainfall for the coming 10 days
Rainfall very similar from this morning. 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. The model now introducing a much more interesting system later in the period over WA that does look spring like, it would lead to widespread rainfall developing later next week.
00z Euro Precipitable Water Values next 10 days
We are now seeing the weather dominated by the high moisture levels over the east and north but it is being blasted out by the dry southerly flow. The moisture will take a while to return and should be back by the end of the week with a spoke coming off the departing low over southern Victoria leading to showers developing with a cold pool aloft and then introduced via the system moving through the Bight. Watching that moisture at the end of the run over WA aligned with a strong cold front.
Rainfall for the next 10 days
Heavy rainfall tonight and tomorrow will slowly ease and move east with showers to follow over the west tonight and tomorrow, slowly decreasing. The weather turns fine and mostly sunny mid week inland in a cold southerly but the coast will still be under the influence of gusty southerly showery winds. The next rainfall event is expected over the weekend with mixed odds on the modelling so will keep the falls conservative for now. But the rainfall frequency is beginning to increase as we head into September.
I will have a climate update tomorrow looking at the coming 4-6 weeks.