A very wet day through parts of the southeast and east, with a slow moving soaker dividing the warm to hot air from the cold air to the south. Many areas recording a months worth of rainfall so far with a trough starting to weaken today, none the less the wet weather has been very productive.
Again the rule to think about, the warmer the air, the more moisture it can hold, the more rain it produces, especially when it is lifted by a sharp cold front and trough which is what we have seen so far during the past 30hrs or so.
The rainfall will extend north and east overnight before weakening further during Sunday. A low may form on the trough as it lifts off the South Coast of NSW which could bring a burst of gales and further rain to the southeast where rainfall totals have been lighter this time around.
Lets look Nationally
Clearly the biggest rain producing system through the region is over Australia and it is shifting east. Either side of the nation, large high pressure, the larger centre over in the west is likely to bring a period of warmer weather to the west early in the week, and a week of settled weather generally for much of the nation from next week.
Current zoom in on where the most action is taking place today - clearly the biggest rain event in many weeks.
State of Play this afternoon.
A result from the airmass clashing over the southeast will be a low forming over the southeast of NSW overnight and during Sunday and bombing offshore, possibly bringing a period heavy rain and squally winds to the South Coast of NSW and East Gippsland - this could lead to a renewed flood risk for parts of the southeast after recent heavy rainfall in August IF it positions itself close enough to the coast.
Temperatures this afternoon - cooler air is filtering north.
Compare the temperatures to 2 days ago ahead of the front and of course you can see why the weather is so active at the moment. You do not have a cold front running into a very warm and humid airmass without some fireworks, so again it is that time of year where we see more volatile weather events. But they are less frequent in normal years, but more productive. Classic Spring event. And as always, given the size of Australia, there will be someone that misses out - EVERYTIME!
00Z GFS Surface Pressure Pattern for the coming 10 days
After we lose the rain band and the low off the east coast, things are quiet for a while with a large high pressure system in force and keeping the weather fairly settled and quiet for next week. Frosts will be an issue for large areas of the south and east with light winds, clear skies and below average temperatures in a dry cold airmass for the first half of the week when we will see the issues increase on that front. Otherwise it will warm up from early in the week out west, some locations could get close to 30C over in SWLD of WA. That warmer air now looking more likely to erode the cooler air over the east later next week. A front coming through the southwest may trigger a large cloud band, but with such a weak trigger it looks to produce more cloud than rainfall for southern areas of the nation. A stronger system may form near SA at the end of the run, but for now keeping much of the nation dry and settled. Will get a better look at that system tomorrow in the medium term forecast.
00z GFS Rainfall for the coming 10 days
After the rainfall tonight and tomorrow over the east, there are no major rainfall events for the coming 7 days at least, and there is a good degree of confidence on that front. Otherwise it is a warm and drier nation through next week. But always got to watch spring as systems can crop up in these competing airmasses, especially once high pressure moves eastwards and opens the door for colder air to move east and north. So at this stage we have to look to about mid month at this stage.
00z GFS Precipitable Water Anomalies next 10 days
A really big dry airmass surging through the nation being propelled by strong southwest to southerly winds behind the front and trough. That air will get a nudge through the nation during Sunday and Monday thanks to the departing low pressure system offshore NSW. Then moisture may be reintroduced over northern parts of the nation with trade winds and via a middle level trough and the jet stream, pulling moisture in from the Central Indian Ocean, not classic IOD related.
Rainfall for the next 10 days
Rainfall is expected mainly through the coming 24hrs with the departing system over the east and then the nation is fairly quiet with dry air dominating the regions heartland suppressing much rainfall activity from the inland and the frontal weather suppressed by high pressure. A weak trough may trigger showers over WA mid week but otherwise it will be trade winds bringing moisture and rainfall chances back up over the northern parts of QLD, running over the NT later in the period. Some chance of rainfall returning to the southeast next weekend but it is a low chance. Rainfall will be heaviest over western Tasmania in a prevailing westerly flow.
Farmers and Graziers Alert
The major drop in temperatures have seen a risk be elevated to high for stock exposed to the conditions over the next 36-48hrs, especially once the southwest to southerly flow gets cranking with a low forming offshore NSW. The weather eases Monday.
Flood Warning/Watch areas continue for the next 2-3 days with the water receding in the south. Check the BoM website to continually see the current heights as they updated by hydrology. This flooding will be something that many in the southeast will be dealing with through Spring.
Spring Flood Risk Forecast - This will be updated in the next week.
Frost Risk for WA again Sunday morning - heads up for SA and VIC/NSW and southern QLD as this will be graduating east with the high pressure system moving in. WA your temperatures move above frost level on Monday morning, still cold but not as cold.
I will have the next update again Sunday morning for the nation then a look at MEDIUM TERM again later in the morning.
Also may have to look at this data set a little closer - Additional Rainfall to come for the next 6 weeks. Looking wetter into October. But will have more to say tomorrow.