But mostly dry and fine elsewhere, so good news for the Ag regions of southern Australia, that most areas can enjoy a fairly settled Christmas and New Year weather wise, with high pressure staying in place today but as we edge towards New Year, the influence of the high to the south will continue to move away to the south, making room for a broader easterly flow across the nation.

But the short term allows for showers and storms for much of northern and eastern Australia, the coverage more widespread the further north you go which is to be expected. For southern and western Australia the drier and hotter you will be this week as the winds veer hot easterly over much of WA.

The changeable weather will be found about central and eastern NSW through southern QLD with a trough meandering about and combining with relatively deep moisture levels coming out of the north and east. So this area will deal with the showers and storms over the course of this week.

Lets take a look


Rainfall Next 10 Days

Rainfall is expected to remain over northern and eastern areas of the nation, no change from this morning so I will persist with the coverage across the nation, but understand where the heavier rainfall is being touted, the falls will vary from location to location. The south and west of the nation is expected to see drier air and stable conditions for much of this week thanks to dominance of high pressure. Once that high moves further to the south, the showers and storms over northern Australia will move further south. Regardless, the models will play havoc with rainfall predictions so a low confidence forecast should be applied to your totals, but the confidence is high in the locations of where rainfall should be through this period.

Tropical Depression Formation

Tropical Depression formation is likely over the course of the weekend into next week as a monsoonal trough deepens offshore WA, NT and QLD. There is a higher chance of a low pressure system forming over the Timor/Arafura Sea region at the moment, but where it goes is largely dependent on where the upper level winds take it, which is determined by high pressure to the south.

Tropical Cyclone Watch

A cyclone is possible in the region north and west of Darwin during the weekend but more likely next week as the monsoonal trough approaches and crosses the coast, the low/cyclone attached to this feature.

Thunderstorm Forecast Wednesday

Thunderstorms are expected to continue in the same zones as per today, through northern and eastern areas of the nation and may appear once again over the western interior near a developing trough. The storms possibly severe over the eastern inland of NSW and QLD and up through the northern tropics where damaging winds and heavy rainfall leading to flash flooding the main issues.

Thunderstorm Forecast Thursday

Thunderstorms may spread further south through NSW and into the ACT, possibly eastern VIC in advance of a trough passing through the southern inland a short wave over Tasmania. The winds may turn gusty over the region with heavy rainfall leading to flash flooding over the eastern inland of NSW and QLD. Thunderstorms could once again be gusty over the Top End but the coverage a little thinner thanks to the monsoon organising offshore. Thunderstorms could be gusty over the southwest and southern parts of the NT into the Kimberly. One or two thundery showers for the SWLD near a weak trough.

Thunderstorm Forecast Friday

Thunderstorms continue for the east and northeast of the nation on Friday with thunderstorms possibly turning severe with damaging winds, large hail and flash flooding a risk. Thunderstorms over the northern tropics will continue and could be gusty at times and extend down through the deserts.

DATA - More details to be found in the video attached at the top of the page.

00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

More details on the day by day breakdown in the video. There is no point in diving too deep into the data as it really is determined by the tropical weather up north and east and where the high pressure ridges through as outlined this morning.

00Z GFS - Precipitable Water Values - Next 16 Days

The values are increasing as the temperatures rise, but we need to lose the westerly flow to the south of the nation and have the easterly winds dominate, that bringing up rainfall chances for areas that have been dry and seasonal for the best part of the last week. The wettest weather is clearly over northern Australia, but how wet remains to be seen and down to where the tropical feature goes.

00Z GFS - Rainfall Accumulation - Next 10 Days

The GFS still wants to take the low close to the east of Darwin and the takes it eastwards, with that rain and tropical moisture heading southeast and eastern areas of QLD. An east coast trough may capture the moisture and bring rain into NSW. The weather over the remainder of the nation may turn thundery but the confidence is low for SA and VIC, but the high confidence on it being dry over the west and southwest remains.

00Z GFS - Rainfall Accumulation - Next 16 Days

The 2 week outlook concentrates the heavy rainfall over northern and eastern Australia and mixed odds over SA and through the interior. It is a very low confidence forecast.

00Z CMC - Rainfall Accumulation - Next 10 Days

The CMC is in line with the GFS in bringing a tropical system through the NT, but differs in relation to where it goes over the country, the CMC saying the easterly flow will bring a flood event across three states before Christmas. The GFS has it a lot slower. The west mostly dry. Numbers are coming up in SA but the confidence is not especially high and it could end up north and east of the state.

More details to come from 8am EDT as I am on my holiday schedule - but still not taking a break - so you can email me if you need me at karllijnders@weathematters.org