A strong high pressure cell will now dominate much of eastern and south eastern Australia over the next four days. As a result, the days are expected to warm dramatically before a cooler change sweeps through south east Australia during Monday and Tuesday 14 and 15 September.
Northerly winds will become a feature and being warm and dry, the first outbreak of warm weather conditions will prevail across a large swathe of south east Australia.
It appears that the first 30C days for the new spring and summer season will occur within New South Wales with maximum temperatures being forecast to reach 30C at least for some inland north west towns. This should be limited in extent to places such as Bourke, Broken Hill and Wilcania.
Even across limited areas of coastal New South Wales, there are forecast maximum temperatures being made for 28C and 29C in places such as Wyong and Penrith.
The attached temperature plots taken from the BSCH for Monday 14 September (1 pm on the 12Z Plot) shows potential for 30C temperature for far western New South Wales, western Queensland and the extreme north west of Victoria around Mildura.
The attached temperature plot taken from the BSCH for Tuesday 15 September (1 pm on the 12Z plot) shows potential for 30C temperature for north western New South Wales and western Queensland. There will be a cool change moving across New South Wales throughout Tuesday but it will remain warm ahead of that change.
When viewing the plot more closely (The 12Z plot) even areas around Penrith in Western Sydney should experience maximum temperatures approaching 28C and maybe 29C. Tuesday appears to present the one and only chance where the first 30C maximum temperature for the season could potentially occur. If it did, it would likely be limited in extent.
Some maximum temperatures being made during the first warm outbreak includes:-
Adelaide - Saturday 27C and Sunday 29C.
Blacktown - Saturday 26C, Sunday 25C, Monday 26C and Tuesday 28C.
Cobar - Saturday 26C, Sunday 27C, Monday 28C and Tuesday 26C.
Bourke - Saturday 28C, Sunday 29C, Monday 31C and Tuesday 30C.
Broken Hill - Saturday 27C, Sunday 30C and Monday 31C.
Griffith - Saturday 23C, Sunday 26C and Monday 27C.
Melbourne - Sunday 24C.
Penrith - Saturday 27C, Sunday 26C, Monday 28C and Tuesday 28C.
Wagga Wagga - Sunday 24C and Monday 25C.
Wyong - Saturday 28C, Sunday 26C, Monday 28C and Tuesday 29C.
This provides some idea what is occurring. There are forecasts being made for some thunderstorm activity to occur with the cool change during Tuesday even through Sydney during the afternoon but any rainfall does not appear to be significant at this stage.