MORNING WEATHER WRAP - THE TROPICAL WEATHER DRIVING THE RAINFALL NATIONALLY.

Now we are getting a better picture on the weather moving through Christmas and New Year, into 2022. For the southern and southwest folk. this period of drier and more seasonal conditions is nothing unusual at this time of year as the focus of rainfall shifts from the Spring time distribution where the rain is heaviest over the east and southeast, to being Summer time, wetter over the north and east.


With La Nina this is more acute and we are likely to see the bias focus over the north and east of the nation this week, rainfall heavy at times.


Now for the rest of the nation, the weather is expected to be settled, near ridging which will lead to some areas going rain free for 10-15 days, again nothing unusual in these areas in Summer, even in La Nina.


The temperatures will begin to climb once we lose the high pressure over southern areas and a new ridge begins to set up camp further south of the nation and that is when humidity will also increase and rainfall chances return to most areas.


Lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall is expected to be concentrated up over the northern tropics, with heavy falls developing, in line with the developing monsoonal burst and tropical low activity. This will form the focus of rainfall nationally. For the east, scattered showers and thunderstorms near and east of a trough meandering through the inland will remain in place but the coverage not as widespread as first thought. The onshore flow over the east coast will send in showers, they may be heavy at times but more likely over northern NSW and into QLD. For the rest of the nation, not much, many areas looking settled through Christmas but humidity may begin to increase as we get to the end of the year and into 2022.

Rainfall Next 16 Days

Rainfall continues to pound the northern parts of the nation with a northwest flow aloft dragging in the tropical equatorial air and leading to heavy falls. The moisture and rainfall heads south through NT and QLD and possibly down into NSW, but this could easily be through northern WA and head south through the Outback and into SA. So something to watch and monitor. This tropical weather will lead to inland flooding over the coming 2 weeks, but exactly where remains to be seen.

Thunderstorm Forecast Tuesday

Thunderstorms are expected to redevelop over the northern tropics and extend south and east throughout much the NT, QLD and into northern NSW. Storms may be severe over parts of QLD and the NT, with heavy rainfall and damaging winds. One or two may be severe thanks to wind convergence over the Mid North and Northern Rivers hinterland. The weather over the southern and western parts of the nation stable with high pressure near by.

Thunderstorm Forecast Wednesday

Thunderstorms following the same script on Wednesday though the coverage seeping a little further south across NSW into the ACT and VIC high country. Storms may possibly be severe through inland NSW extending through southern and western QLD and throughout the NT with damaging winds and heavy rainfall leading to flash flooding. A few thundery showers near a weak inland trough of WA during the afternoon and evening, but these are not likely to be severe.

Thunderstorm Forecast Thursday

The trough over WA lifts north and consolidates towards the tropics, so storms increasing over WA, some of these turning severe over the border with the NT and back through the Top End and southwards into the Gregory and Tanami regions. Out east, a stagnant trough will deepen over inland NSW so the coverage of showers and thunderstorms increasing, some of these severe with damaging winds, heavy rainfall and large hail, mainly over northern inland NSW and southern QLD.

DATA - Refer to the video for the GFS comparison


12Z Euro - Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

Note the tropical features over northern Australia dictating the moisture spread across the nation. Also as mentioned in the video, the ridging to the south will beat down that fast flow pattern and you will see easterly winds take over much of the nation and the westerly winds be removed from the southern areas. Once the ridge moves south of Tasmania, then rainfall chances will spread from the north of the nation into southern SA and VIC where it will be dry for a while until this happens. Hot out west, but seasonal to below seasonal elsewhere. All eyes also will be on that tropical low over the north later this weekend into next week.

12Z Euro - Precipitable Water Values - Next 10 Days

Once we lose the fast flow pattern to the south, this will allow the moisture to seep southwards from northern Australia, but the ridge will hold out that moisture reaching the southern states, so for now dry weather for much of southern Australia for the week, unsettled and humid over eastern and northern Australia, but it all comes south once the monsoon comes to town up north from the weekend into next week.

12Z Euro - Rainfall Accumulation - Next 10 Days

More information in the video

12Z CMC- Rainfall Accumulation - Next 10 Days

More information in the video

12Z GFS - Rainfall Accumulation - Next 10 Days

More information in the video

12Z GFS- Rainfall Accumulation - Next 16 Days

More information in the video



I will have more on the 6 week outlook coming up from about lunchtime and then an evening weather wrap nationally - as we are on holiday schedule through the Christmas period. If there is any severe weather events then more focussed charts will be prepared (as we saw over the weekend).