Getting closer to the busy time of year for many of you and the weather is set to cause some headaches through this period, particularly from QLD through NSW into VIC. Severe weather issues are expected with storms producing all modes of severe weather and higher humidity also creating an atmosphere more supportive of widespread rainfall developing throughout the nation's north and east.

The signals remain unchanged and in fact, increasing the signal for rainfall over northern Australia (not unusual being the wet season - but the intensity of that rainfall is unusual) and that rainfall/moisture spreading east and southeast throughout the nation.

Lets take a look at the latest details


Rainfall Outlook Next 6 Weeks - October 26-December 10th 2021

% chance of exceeding the median rainfall for the coming 6 weeks

The rainfall chances exceeding the average through this period are now increasing nationwide as we get deeper into November into early December. Now as mentioned, uneven distribution of rainfall with thunderstorms means some areas will get clobbered with a month's worth of rainfall where down the road will wait. Then the next round of storms brings the places that missed out a clobbering and the places that got the first batch of rainfall, miss out. Overall the trend from the models is wet. How wet it gets, remains to be seen but the higher odds of above average rainfall is over the NT, QLD and NSW. The further west you go through the nation, it is a higher chance of more seasonal rainfall but certainly another wet lead into Summer is expected based off all the data sets below.

Temperature Outlook Next 6 Weeks - October 26-December 10th 2021

% chance of exceeding the median temperatures for the coming 6 weeks

No change in the guidance from last Friday though we have moderating temperatures for the northern parts of the nation thanks to higher than average rainfall chances moving into November and December. There is a high chance of an early onset monsoonal burst.

Humidity Outlook Next 6 Weeks - October 26-December

% chance of exceeding the median humidity for the coming 6 weeks

Higher humidity values against the average have been observed for the past 6 weeks over northern and parts of northeast Australia. This humidity is expected to sweep further south and east during the coming 2 weeks and a marked change in conditions can be expected for northern SA, NSW and northern and eastern VIC. This will be accompanied by more rainfall and thunderstorm activity. For the remainder of SA and a decent chunk of WA, higher humidity values are expected as we go deeper into November and kick off December with inland troughs pulling moisture south and southwest from the NT and Kimberly.


No change to the guidance in the climate models since last week, we know the Indian Ocean is negative phase and we are seeing that impact on the overall medium term forecasts with moisture streaming in from the northwest into the tropics and then southwards into the interior. This influence will continue for the coming 6 weeks across the nation. The SAM is currently trending more positive as we end October and I am of the belief as we go through November, the SAM is likely to be positive, thus increasing rainfall chances along the east coast as you can see in most data sets below. Finally the ENSO which I will speak more about in another post is likely to shift into La Nina during the latter part of November into December, HOWEVER, the shift into the La Nina and the impacts felt in Australia, usually has a lag of about 4-6 weeks and so this is likely to be experienced after Christmas at this stage over the continent. The bigger impacts from that over the north and east.

DATA - Refer to video for more on these sets of data


Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - October 26th -December 10th 2021

A very wet signal for much of the nation with potential flood risks for the southeast and east with these rainfall values. The wet signal increasing over the northern parts of the nation with the chance of early season heavy falls and potential for flooding in some locations in north QLD and the NT. Higher humidity values and warmer temperatures will increase your risk of mildew, rot and other fungal issues for your crops, particularly those summer crops that are in flower, fruit and at risk of impact from these conditions in the east and south. The severe weather risk from thunderstorms is running high to very high through this period with rainfall likely to be derived from storm outbreaks through the east and periodically, large scale rainfall events sweeping west to east. We have about 2-3 in the medium term (16 days).

Euro Rainfall Accumulation Control Data - Next 6 Weeks - October 26th -December 10th 2021

This highlights the significant early onset rainfall impacts not just over the north but over the remainder of the south and east of the country. There could be some early season rainfall records for parts of northern Australia if this verifies.

Euro Rainfall Anomalies - Next 6 Weeks - October 26th -December 10th 2021

That is a VERY WET look or northern Australia with rainfall anomalies 100-200mm above normal for the 6 week period. The rainfall anomalies along the east coast 50-150mm above normal. At this stage most of the nation seeing a 25-75mm increase on normal for this period.

CFS Rainfall Accumulation Ensemble Data- Next 6 Weeks - October 26th -December 9th 2021

As you have seen over the past week the wet signal continues on this product and the shorter term models now starting to pick up on that.

CFS Rainfall Accumulation Control Data- Next 6 Weeks - October 26th -December 9th 2021

As mentioned in previous updates, the fact that this agency has a drier tropical picture but has heavier falls over the east and southeast suggests that falls over the east and south of the nation may be too light when looking against the Euro and other agencies, so once again not only is caution required when interpreting this data, but comparing to other agencies is key too. The wet signal is there, how wet....well that is the $64000 question when looking at other models going harder on the rainfall outlook.

GFS Rainfall Accumulation - Next 5 Weeks - October 26th -November 28th 2021

This model has now getting wetter after being a dry outlier two weeks ago. Note the heavier rainfall coming into the central and eastern parts of the nation connected to the tropical north.

GFS Rainfall Anomalies - Next 5 Weeks - October 26th - November 28th 2021

Now running wetter than last update which means that the rainfall signal is increasing across the nation.

CMC Rainfall Accumulation - Next 4 Weeks - October 22nd -November 22nd 2021

A very damp four weeks on the way, as advised in the video, your short and medium term forecasts will chop and change I am cautioning all that are making preparations for harvest to be aware of the forecast rapidly changing over the coming week, most likely trending wetter for southeast and eastern Australia. Something to watch.

CMC Rainfall Anomalies - Next 4 Weeks - October 22nd - November 22nd 2021

Very wet look, and it is increasing each update. The west turning wetter now in the latest outlook for the medium term too. Numbers are coming up over SA and into the NT and northwest. This is picking up on the warmer waters right across northern Australia and the IOD.


Euro Temperature Anomalies - Next 6 Weeks - October 26th - December 10th 2021

This is still closest to the post where other models are running too cool or too warm. There is likely to be below average weather for the western interior of WA and through eastern parts of Australia, especially over the coming 1-2 weeks before conditions warm further. We will feel some of that warmer and humid weather in the coming days but then turn cooler, humid and wetter again through November. The north will be the opposite, running warm for the coming week before the rainfall increases and moderates temperatures. Overall this is indicative of a wet and stormy period with inconsistent temperatures throughout the continent and no especially long run of hot or cooler weather for any one area away from the southwest.

GFS Temperature Anomalies - Next 5 Weeks - October 26th - November 28th 2021

The GFS is still running way too warm in my opinion.

This product will be updated again on Friday.

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