MEDIUM TERM FORECAST UPDATE - AFTER THE RAIN THIS WEEKEND - COOL AND DRY FOR MOST OF NEXT WEEK.

So it has taken about one week to sort the modelling on this current system out, all models now in reasonable agreement with the moisture from QLD lurching south bringing areas of rain and storms into the eastern states, patchier falls for SA, heavier rainfall for NSW and VIC with some areas possibly recording 100mm of rainfall through the event.


I am now posting flood watches for the high country in northeast VIC and southeast NSW west of the divide with the heavy rainfall combined with snowmelt seeing the river systems heading into minor flood at least through the weekend.


Flood Watch - My areas of watch for the coming weekend after the heavy rainfall has pushed through. Some areas are already under flood warning near Condobolin and north of Wagga while it has eased in recent days over the northeast of NSW.

Latest Update for the coming 2 weeks below

THE CHARTS

Rainfall for the next week - September 2nd-9th 2021

Main rain event coming through the south and east is over the next 3-4 days before the high comes in and dries much of the nation out next week.

Rainfall for the following week - September 10th-17th 2021

Signals for an upper low to move over the southeast later next week into VIC and NSW bringing areas of rain. Another upper trough over WA with showers and storms passing through later next week with further light falls. The easterly winds will bring the heavier rainfall to eastern parts of FNQ as per the shift to the build up and trade winds returning. Plus SSTs off the QLD coast are well above average. The lack of influence from the Indian Ocean quite noticeable in the medium term.

Rainfall Anomalies for the next 2 weeks

Clearly the rainfall coming over the next 4 days is evident in the chart below, the high pressure dominance over the Bight will bring dry weather to the southern coasts of the nation. The tropics may see unseasonal coverage of rainfall as per what occurred with a thunderstorm complex over far northwest QLD which saw 3 months rainfall be observed north of Mount Isa.

Temperature Anomalies for the next week - September 2nd-9th 2021

The warm to hot air over the southeast and eastern inland will be pushed out during the coming days with a number of below average days of temperatures expected through the weekend into mid next week, before conditions improve to seasonal values from WA mid next week then into the eastern states into mid month. The middle of the month looking increasingly warmer and drier through much of the northwest of WA and this hot air will be drawn south through mid month after a cooler spell with drier air over the nation.

Temperature Anomalies for the following week - September 10th-17th 2021

That cooler bias over eastern inland Australia is the residual cooler weather mid next week, that will be resolved by next weekend with the majority of the nation at this time looking above average temperature wise as we go towards mid month. How hot remains to be seen, but it is quite possible that the weather we have experienced during this week may be realised again.

THE DATA

GFS - Synoptic Scale and Rainfall - Next 2 weeks

GFS - Precipitable Water Anomalies - Next 2 weeks

GFS - Rainfall for the coming 2 weeks

GFS - Temperature Anomalies - Next 2 weeks

EURO - Rainfall Anomalies next 2 weeks

CMC

GFS

The BoMs outlook for Spring is very aggressive and so again, this updates hopefully today and I encourage you to cross check my forecasts against other agencies to get a good sense of what is out there, however with charts with green on it, does NOT mean you are guaranteed above average rainfall. Remember if you are in dark green below, there is a 20% chance you may get seasonal rainfall or below average falls too. It is just not as likely.

I will have more this afternoon and there will be more refining to the rainfall distribution coming up over the east, but largely the area of heaviest rainfall has been identified now and the process of that system moving through is now well modelled. Next week it is looks fair to print out a benign forecast before unsettled weather redevelops in the medium term with warmer weather.


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