MORNING WEATHER UPDATE - STORMY FOR PARTS OF THE EAST AND NORTH, THE REST ENJOY A SETTLED SUNDAY.

It is a much more sedate weather setup for most of us today, with a high pressure system gliding through the south of the nation with the main centre sitting south of SA. This is allowing for a easterly wind regime to prevail, with the mild and humid winds feeding troughs to produce showers and storms, running through the continent, drying out and heating up, bringing warm to hot sunshine for SA and WA.


The winds are expected to remain dominant easterly for the best part of this week, a with mild fluctuations in the pressure pattern over southern areas (high pressure reconsolidating), this will offer some variation in temperatures for the outlook period but not much in the way of rainfall.


The main weather this week coming is not only the heat through southern and western parts of the nation, but the trough deepening over eastern Australia which will produce widespread showers and thunderstorms, some possibly severe through QLD through this week, but extending through to NSW and VIC mid to late week before clearing out by the weekend.


There are hints of a larger scale rainfall event during the following week as the pressure pattern shifts wetter, the winds turn more unstable east northeasterly across the continent and with the high moving south away from southern Australia, the low pressure will be allowed to dominate proceedings, so expect that to be the next opportunity for widespread rainfall.


Lets take a look


FORECAST

Rainfall Next 10 Days

Rainfall is interesting for the week ahead, the west remaining dry and settled with high pressure close by and that goes for much of SA. There may be a thundery shower that may sneak into the east later this week. The main rainfall activity is over QLD and NSW with a deep trough through this week. Some of the storms producing locally heavy falls and flash flooding. The onshore winds are expected to produce showers for the QLD and NSW coast, some of these could be heavy through QLD. The trough deepens during Wednesday and heads west through NSW and dips into VIC. The showers and thunderstorms could turn severe during Wednesday through large parts of NSW and over VIC Thursday before the stormy weather contracts north and east into NSW and QLD on Friday and into next weekend. The tropics remaining active this week but the storms may increase in coverage further later this week into the weekend coming with heavy falls developing. Will be watching that moisture closely as it moves south and west through the tropical north. As we end the period, you will see the build up of moisture through the central and western interior of the nation and the eastern seaboard will see a significant amount of showers and thunderstorms with some heavy falls developing for and east of the divide.

Thunderstorm Forecast Sunday

Thunderstorms are likely to redevelop in the same region with a trough lingering through the eastern inland of the nation. The thunderstorms could be strong to severe with heavy rainfall leading to flash flooding being the main risk in the east. For the north, the showers and thunderstorms will continue with the usual build up conditions.

Thunderstorm Forecast Monday

Thunderstorms will continue to work west through NSW and QLD with a significant amount of moisture being drawn south and southwest into the region via northeast to easterly winds as well as left over moisture from the system of last week. Storms will continue to bring the chance of heavy rainfall leading to flash flooding. The tropics will continue to see the routine showers and thunderstorms.

Thunderstorm Forecast Tuesday

The moisture and instability begins to move further south through NSW with the thunderstorms reaching down into eastern Victoria and extending all the way north to Cape York, through the Gulf Country and west into the Top End. Heavy rainfall and damaging winds would be a concern through NSW and QLD and parts of the Top End. The humidity will begin to move further south into VIC during Wednesday increasing storm chances.

DATA

12Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

The pressure pattern is less dynamic now with just one trough on the board over the east coast triggering showers and storms today, that trough then moving west into the interior throughout the coming days, becoming the focus for wet weather throughout this period. The northern tropics remaining very much routine with the usual storm activity. A mid week trough is expected to drive showers and thunderstorms and much warmer weather for VIC and NSW before the southeast winds return and lop the temperatures back. The west is warm to hot today but a milder southerly flow will develop for the first part of this week before the temperatures heat up once again. The main rain and thunderstorm activity will be connected to the trough in the east and then via the persistent easterly winds. So those needing dry weather over QLD and parts of northern and eastern NSW, there is no dry spell in the coming 14-16 days. Watching the tropical weather closely too as the monsoonal surge moves further south of the equator.

12Z GFS - Precipitable Water Anomalies - Next 16 Days

Deep moisture remains in force over QLD and northern NSW throughout this period leading to the prolonged period of thundery humid weather right through until mid December. This airmass is a powder keg, in the form of waiting for a deep low pressure trough to lift it into a much more organised rainfall event. Looking at the charts, there is no evidence of an organised rainfall event at this time but the coverage of showers and thunderstorms will be more widespread at times, like later this week and again from the end of the first week of December in these regions as troughs deepen. You can see that impact even this week over VIC and western NSW as the new trough moves through. Otherwise fairly routine moisture levels elsewhere, but the nation does turn much more sultry as the temperatures rise in line with higher humidity values, so it will become more tropical as we go.

12Z GFS - Rainfall Accumulation - Next 10 Days

It is in good agreement with the other models having the heavy rainfall bullseye over the northeast and east of the nation. The showers and thunderstorms increase during the latter part of this week with a trough lingering over parts of VIC and NSW with heavy falls where storms form. The west dry for much of the period but the showers and thunderstorms may redevelop with moisture sweeping southwest and south out of the tropics. The rainfall will be more uneven in distribution away from southeast, central and eastern QLD and northern NSW. Finally, numbers are coming up with the mid to late week trough over VIC and central NSW.

12Z Euro - Rainfall Accumulation - Next 10 Days

The Euro tucks the heavy rainfall chances through QLD where moisture is stuck through this period, unable to be swept out which has been the guidance for the past week. So daily showers and thunderstorms expected to continue with high humidity. Coastal showers to continue through the state as well. The showers and storms will creep into northern NSW as well with heavy rainfall the main concern with storms through the flood zones. During the coming weekend, the rainfall may increase in intensity with showers and thunderstorms becoming more widespread and a trough deepening offshore the east coast may increase the coverage of rainfall for coastal areas of northeast NSW and much of southeast QLD. This may extend south down the NSW coast in the medium term. The remainder of the nation looks fairly quiet but note the moisture sweeping south from the tropical north.

12Z CMC - Rainfall Accumulation - Next 10 Days

Rainfall on the CMC is moving around a lot, it had heavier rainfall through SA last night and this morning has it back over QLD and NSW which I think is the right solution. Noting that tropical rainfall off northern Australia increasing throughout the outlook period with heavy falls. That moisture sweeping south and southeast throughout Australia.

12Z GFS - Rainfall Accumulation - Next 16 Days

Rainfall as mentioned from about the 5/6th of December may commence becoming more widespread with thundery weather in all states and territories as moisture deepens and troughs start to take over the nation into mid month. The rainfall most widespread over the eastern and northern states. But the warmer weather coupled with a deep moisture supply in a stagnant pressure patter, this is likely to be a longer duration period of unsettled, humid and warmer weather. This may lead to more issues around the usual summer fungal nasties for those with the Summer crops.

Latest Seasonal Update due out by lunchtime looking at Summer 2021/22, Autumn 2022 and a preliminary look at Winter 2022.