MONDAY MORNING WEATHER - DESPITE SOME SEVERE STORMS IN THE COMING DAYS, IT IS LOOKING MUCH QUIETER

And I think those in the disaster zones can be thankful for that but in other areas, which have missed out and are screaming for rainfall, not likely to be a great week of weather for you.


We can see the climate drivers, the hustlers being the SAM and MJO not quite in phase at this time. So that sees the nation take a little bit of a break from the high impact severe weather on a large scale.


Areas of inclement weather for the coming days will be found over the northern tropics with the build down thunderstorm activity and across the eastern inland (so this time areas of eastern SA through western NSW and dipping south into western VIC and north into southwest QLD). This area of thunderstorms over the southeast and eastern inland could produce some hefty falls, but they won't be widespread, but a few of you could see a lot of rainfall at once while others miss out.


Out west, another area of interest to watch which I touched on last night is the emergence of the first large long wave trough over the eastern Indian Ocean which could help to pull down moisture from the tropics well west of the nation. This could see beneficial rainfall over parts of Ag WA through the weekend if not next week and that has been an idea that is gaining traction with the SAM being in a more negative phase.


Across the northern tropics we will likely see an increase in rainfall, especially where the trade winds converge along the coast between Bowen and Cooktown where heavy falls are possible this week.


The weather along the east coast seasonal with no evidence of severe weather at this time, and overall, the weather in the south and southeast will gradually dry out and warm up once again ahead a front during Thursday.


The fast flow pattern over the south of the nation is a hallmark of the cool season and it's emergence signals a shift is likely on the way before we know it.


Lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to remain on the lighter side this week, as we take a breather from the heavy wet signals across the climate agencies. The guidance suggests further below average rainfall chances for many inland areas. But there have been rumblings, not overwhelming, of the chance of rainfall increasing over the western interior later in the weekend into next week with the development of a large long wave trough offshore the west coast. That may be the major rainfall feature to watch away from the tropics. In the short term, watching the trough and trade winds producing the heaviest rainfall nationally between Cooktown and Bowen this week. Storms which will be locally severe with heavy rainfall in isolated spots of the eastern and southeast inland will continue for the next few days before a drier westerly change moves through later this week. Spotty showers for the east coast with mainly light falls daily. It is a much quieter period nationally but watching the medium term very closely for you out west.

Thunderstorm Forecast Monday

Thunderstorms are forecast to move further west through NSW and into SA through Monday with the chance of storms becoming severe over inland SA, with damaging winds and heavy rainfall a chance. Thunderstorms also likely to develop over elevated terrain through VIC but no severe weather expected. Thunderstorms will extend back northwards through the NT into the tropics where storms may be gusty with damaging winds and heavy rainfall leading to flash flooding. Storms over WA will be confined to the Kimberly region and in QLD, confined to western areas and through the Gulf Country and Cape York where heavy rainfall may lead to flash flooding.

Thunderstorm Forecast Tuesday

Thunderstorms will continue from overnight and into Tuesday for large parts of Central Australia extending south into the Ag areas of SA and through to the Southeast where thunderstorms may turn severe with heavy rainfall and gusty winds. Thunderstorms over the tropics also increasing in coverage and extending southwards into the outback where storms could be severe with damaging winds. The thunderstorm risk over eastern parts of the nation low with the main lifting trigger sitting over western VIC, NSW through SA and into the NT. That looks to be the focus for now and the risk of severe weather is moderate.

Thunderstorm Forecast Wednesday

The trough over SA begins to weaken and therefore the thunderstorm coverage decreases,, but they will still be scattered during the afternoon and evening for most of Ag SA, especially into the east and into western VIC. Thunderstorms generally will be under severe thresholds as the dynamics aloft are not as robust. Over the north the storm coverage should continue to be scattered to extensive with severe weather possible, damaging winds likely and now the introduction of flash flooding too for parts of the Top End. The moisture from the tropical expression of storms will also feed another trough over the southeast and east of the NT and into western QLD with gusty winds possible but here most of the storms should be below severe thresholds.

DRIVERS TO WATCH


SOUTHERN ANNULAR MODE - SOUTHERN OCEAN

The SAM is tending negative this week with the impacts now being reflected in a drier picture for much of the nation. So this period of negative values will be short, but enough to bring drier more stable air through the region. The SAM looks to remain neutral through the middle to latter part of the month but in recent runs, there has been a shift back to a positive phase in about a week, but will watch closely. Generally neutral conditions to continue into the latter part of the month.

MJO - TROPICS

The MJO looks to rotate through the phase 4-5 range in the medium term, but most likely to sweep north of the nation but increase rainfall none the less. The moisture from the Indian Ocean is expected to be the region to watch with moisture being lofted from the region south of Bali and then southeast in the upper levels through the west and central areas of the nation and into frontal weather south of the nation. If we see the clash of the SAM in a negative phase with the MJO rotating around the north of the nation, northwest cloud bands may increase in the medium term but there is evidence above that we are seeing a shift to neutral/positive SAM values with the MJO moving through the north.

Scenario 2 - This would be the way the break comes or develops on the current guidance from above.

The rainfall remains excessive through the Summer and into Autumn with no requirement for a rainfall break in the east. We are seeing that now. But sometimes what happens is that the persistent easterly winds that develop via high pressure in the Tasman Sea, pumps moisture deep into the eastern inland and then the moisture spills further west into Central Australia and then cold fronts start to pick up the moisture, eventually spawning a large scale rain event that is slow to move throughout the eastern and central inland. We are seeing some evidence on the charts that this may occur in the medium term, but again over areas that don't need rainfall, in part due to the persistent and heavier rainfall we have seen in the Spring and Summer.

DATA - Refer to video for more information and the model comparison and context about all the forecast products you see from me.


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

The latest Euro showing a more traditional Autumnal period with a lower amplitude in the pattern which is means the weather not as active over the coming 10 days. We can see the showers and storms over the outback of NSW and SA throughout the coming 2 days, extending into VIC and possibly southern NSW and southwest QLD. A few showers for the NSW coast tending more scattered in QLD and tending to heavy rain over the FNQ coast with local flooding developing in some coastal estuaries this week. Over the north, tropical showers and storms with damaging winds possible most days this week with a stubborn pattern continuing. Out west, the models do not know what to do and do not settle on a solution just yet, for now I would keep it dry. But there is some chance of this forecast changing dramatically in the coming few days as the drivers settle on a solution. But overall this is normal for this time of year, low confidence forecasting in the shoulder seasons is very normal.

12z Euro Precipitable Water Anomalies - Next 10 Days

Moisture content at near seasonal values for much of the period nationally. The deeper moisture found with the trade winds over the north of the nation with a strong easterly flow. The flow tending more northeasterly over the NT with heavier rainfall developing with storms through the week with a deeper moisture profile. Above average moisture over the western NSW and through eastern SA will kick off a few showers and thunderstorms during the next couple of days. The remainder as mentioned see average and seasonal humidity values for now but with the MJO getting closer and the SAM being volatile from day to day, this forecast could change dramatically as we go through the week and do not be shocked we see a band of rain and cloud traversing the nation from northwest to southeast.

12z Euro Rainfall Accumulation - Next 10 days

Refer to video for more information

12z GFS Rainfall Accumulation - Next 10 days

Refer to video for more information

12z CMC Rainfall Accumulation - Next 10 days

Refer to video for more information

12z Euro Rainfall Accumulation - Next 15 days

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12z GFS Rainfall Accumulation - Next 16 days

Refer to video for more information

More coming up on the severe weather threats moving through the next 3-4 months as we transition from Autumn into early Winter. Will we see more flooding? Above average severe weather events, in the form of damaging winds, large hail, severe frosts....it is the time of year....