The spring roller coaster continues across the nations as frontal weather continues to move across the south of the nation, competing with the warmer drier air over the north. It is creating volatility in the weather forecasts, modelling and creating havoc with trying to place rainfall events and their impacts on temperatures.
Here is the latest details this evening.
Rainfall for the next 10 days
The weather is very hard to pin down and so keeping rainfall more as an area of chance rather than being focused on specific rainfall totals later this week. In the short term the rainfall looks to be mainly coastal, but there is a parcel of colder air riding up through Victoria tonight and this is starting to move northeast and will provide enough instability to see showery weather increase for eastern NSW Monday and Tuesday. A low will form on that trough offshore and move east mid week. Then how that low behaves in the Tasman will create complications for the system moving over SA later in the period, which is yet to be determined.
Thunderstorm Forecast - Monday 13th of September 2021
Thunderstorms are possible in a showery cold airmass moving north from VIC into NSW during Monday afternoon. Storms are likely to be isolated but potentially gusty with small hail the main threat. With a dry airmass riding in under the trough, the likelihood is for moderate rainfall with the storms where they form. Conditions ease later in the day and contract northeastwards.
Hail Risk Forecast - Sunday into Monday
The hail risk overnight in Victoria will diminish and contract to the coast as the sun goes down, but then with the day time heating process, the hail risk will increase dramatically as the trough moves over southeast NSW into Central areas later. Just small hail risk at this stage.
00Z EURO - Surface Pressure Pattern and Rainfall Distribution - Next 10 days
The showery airmass with a cold front is expected to move northeast and bring moderate coverage of showers to the eastern coast of NSW on Monday through Wednesday, while the rest of the nation resides under high pressure. Then we track the high through to the east and by Wednesday the majority of the nation should be drying out with stable air. Up north, on the periphery of the high, humidity will lead to showers and thunderstorms each afternoon. A front approaching the southwest of the nation during Wednesday night into Thursday may bring another large burst of rainfall through the region, before that system moves east. It is anticipated the system will drag in a large amount of moisture from the northwest but as mentioned in the video, become decoupled from the lifting mechanism, that may see rainfall become patchy and light over SA before reappearing over NSW and VIC. It is a low confidence forecast.
00Z EURO - Precipitable Water Anomalies Next 10 days
Precipitable water anomalies are painting the picture of the battle underway between the dry air and the humid air up north, they are becoming intertwined, meaning rainfall chances are increasing then decreasing from run to run. As mentioned on Friday and yesterday plus in the video, we are tracking a drier change through SA with the system falling apart from SA, but then a rain band may reemerge over the eastern states as a trough finds the moisture and lifts back into areas of rainfall there. So there is a heightened risk of better rainfall once again over the east, the southern states probably miss out with this feature and QLD again looking dry, but watch the trough become stuck over QLD later in the run, as that is a chance of setting up the inland trough for QLD and maybe bringing up the chances of rainfall to end the month and to kick off October. The northern tropics also battling with the drier and humid air.
00Z EURO - Precipitation Next 10 days
Lean is the word I would use nationally, with another quiet week, but it is low confidence as outlined in the video.
I will have a wrap of the models later on tonight regarding rainfall later this week, as there is a lot riding on this system for many in SA and points east.