The heat is building up as expected in September with the seasonal shift well and truly underway. The conditions are a few weeks ahead of schedule in terms of rainfall frequency across the region with a relatively good supply of moisture and colder upper levels supportive of convection.

A drier surge has slowed its progression northwards in the last day but it will get a kick along by a change rolling through the southeast this weekend.

Thunderstorm Forecast Wednesday

The thunderstorm risk is diminishing from the southeast as the drier air begins to surge northwest over the coming 24 hours, this sweeping the humid air away by Friday. Thunderstorms mainly offshore during the morning and then very isolated over the mainland during the afternoon. Better chance is with Hector over the Tiwi Islands during 2-5pm.

Rainfall next 10 days

Rainfall is expected to be spotty and random across the north in the coming days as per yesterday. The weather is anticipated to dry out from the south and east during Thursday with heat levels coming down during the weekend with a nice punch of drier air. The south dry for now, but keeping an eye on that rain band that will break out in response to the temperature battle going on in region, and that weak impulse of moisture from the northwest.

Broader view.

Euro 00z Surface Pressure Pattern and Rainfall Distribution - Next 10 days

Pattern rather benign for much of the inland as expected with high pressure in full control. We are tracking a front still through WA from tomorrow and that will be the focus over the southern and southeast states this weekend. Less rainfall coverage than GFS (as you can see from the video) but widespread cloud and colder weather developing over the weekend is expected. There will be another cold front next week for the southeast while the rest of the nation stays dry and settled for the remainder of the outlook. The weather is also set to turn just beyond the period for parts of inland SA and WA with a pressure trough nearby and humidity returns to the NT and QLD.

Euro 00z Precipitable Water Values - Next 10 days

This again is largely unchanged from this morning, though GFS has more moisture available across the nation, where this run is a lot drier thanks to the gusty southwest flow and cold fronts clipping the southeast. The moisture is set to return to inland areas over the north and northwest during the outlook period but a lack of unstable air will mean rainfall remains low.

GFS 00z Precipitable Water Values - Next 16 days

I just wanted to compare with the GFS to show the difference in moisture placement and the impact this has on the rainfall out put from the models in the coming 2 weeks.

Euro 00z Rainfall - Next 10 days

Soaking rainfall for the SWLD likely with the passage of a cold front during Wednesday afternoon and evening and through Thursday. This front runs out of steam as it moves further east. The east coast and the tropics will also begin to dry out in response to a high moving in. The front is expected to weaken as it moves further east by the end of the week. Rainfall remains light and patchy for much of the nation with a good supply of moisture coming down the northwest to southeast but sadly the lifting mechanism just not quite there. Hence not much on offer for now across SA. This model may be a little drier than others. You can see the GFS output in the video with my analysis.

I will have the model wrap coming up later this evening from 9pm.

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