HARVEST OUTLOOK UPDATE - THE WET AND STORMY PHASE CONTINUES

As we have been mentioning since July, this weather should not be a surprise to you if you have been here since launch day. It is pretty much so far, following the script of wetter as we go, the warmer the air gets, the more rainfall and volatile weather events we will see and that seems to be the case.


The scary thing is over the nation's south, the weather has been cooler than normal, so the blessing in that, the dampening down of the destructive weather potential we could have experienced yesterday through VIC, NSW and QLD.


But that luck will run out in the coming weeks with warmer weather obviously on the way as we enter November and the wet signal intensifying for the east and southeast and now over central parts of the nation too.


No video today as the data is largely unchanged but will have a seasonal outlook video on Sunday for Summer 2021/22 - waiting on a little more data to come in.


FORECAST CHARTS


% chance of exceeding the median rainfall next 6 weeks - October 15-November 28 2021

The wet bias continues for much of the nation's north and east, again we have seen many areas record a months worth of rainfall this week with scattered showers and thunderstorms over the southeast and eastern inland. We have a strong low developing southeast of Tasmania which will bring up further heavy rainfall over VIC and TAS. These events are likely to continue to unfold over the next 4-6 weeks. We are likely to see a trough of low pressure deepen over the northern and eastern inland during later next week, that trough, which is a permenant fixture through summer time, is setting up early this year, and will see showers and thunderstorms most days throughout the coming 4-6 weeks over inland QLD, extending into the NT and over the tropics. This is normal. There will be moisture building from the Indian Ocean this week and multiple bursts are likley to occur from the basin over the course of the next 6 weeks. The weather turning wetter than normal over inland areas of the west. SA sits in between it all but there is likely to be some reasonable rainfall events move through, already some areas recording near normal rainfall for October which is good news. Some of the rainfall over the southeast and eastern inland of the nation will keep the flood risks elevated for the upcoming period. We have seen flood warnings increasing following rainfall this week and more flooding this weekend. A sign of what is to come.

% chance of exceeding the median temperatures next 6 weeks - October 15-November 28 2021

Starting to see a slight warming bias in the trends across all modelling but no real change for the east with above average rainfall and persistent cloud cover likely to keep the cooler signal going and quite cool over the southwest of the nation with persistent ridging and cloud cover thanks to the Indian Ocean Dipole. The north is looking hot and humid with increasing rainfall starting to offset the higher heat levels for the final three weeks of the outlook.

CLIMATE DASHBOARD

No change to the guidance in the climate models this 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. Even in the short term, watch the moisture stream into the large low pressure system near SWLD of WA early next week. The ENSO region (which I will have notes from earlier this week underneath) is trending towards a La Nina phase and the SAM is trending positive through the coming week. That will see storms become more widespread over the north and east during the course of next week and a dominance of easterly winds returning across the nation lifting inland rainfall chances for eastern Australia. Near seasonal expectations seems fair for SA and points west.


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


RAINFALL

Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - October 15-November 28 2021

Very wet signal continues. For now the guidance is unchanged during this period and harvest will be very tricky and disrupted by rainfall, it is a very high chance if you are living through the east and southeast. I spoke about this Tuesday, Severe weather from thunderstorm activity may increase further in the coming weeks with damaging winds, large hail and flash flooding all an above average chance against seasonal averages. We know what has unfolded across the east this week so we must pay attention now to each severe thunderstorm outbreak.

Euro Rainfall Accumulation Control Data - Next 6 Weeks - October 15-November 28 2021

Heavy rainfall bias over the northern tropics, along the southern coastal areas and the east coast. The shift in this modelling has now been the factoring in of the Indian Ocean influence - and now we see the interior caked in 50-100mm rainfall projections.

Euro Rainfall Anomalies - Next 6 Weeks - October 15-November 28 2021

The Euro is increasing the rainfall for the period, as per the climate drivers, the IOD is forecast to peak during this time, the potential La Nina building over the Pacific and the elevated SSTs around the nation, wet weather is likely for the eastern half of the nation. The blue shading indicating rainfall above the average by 50-100mm as an average, within these zones your number will vary, especially in the tropics and now over the interior. This signal has remained unchanged for a while.

CFS Rainfall Accumulation Ensemble Data- Next 6 Weeks - October 15-November 28 2021

Very wet signal continues from the CFS, no change in guidance.

CFS Rainfall Accumulation Control Data- Next 6 Weeks - October 15-November 28 2021

Some very heavy falls of 200-300mm possible if this is right through inland NSW and northern VIC and now that threat could seep into eastern QLD as well. Something to watch. Some runs have introduced 400-500mm for parts of eastern QLD and NSW this week, not in this particular run.

GFS Rainfall Accumulation - Next 5 Weeks - October 15-November 17 2021

Rainfall largely unchanged from run to run, though some members of the GFS have been placing a heavier bias over the east coast, some members continue to have 300-400mm of rainfall over the NSW and QLD coasts during this time and some members have 200-300mm for inland parts of NSW and VIC. Storm season is expected to ramp up rapidly during this coming 2-3 weeks over the north and east and may become persistent over inland QLD and the NT. That would support the inland rainfall being above average. This model does not quite see the Indian Ocean influence. Therefore it is one of the drier outlooks across the board.

GFS Rainfall Anomalies - Next 5 Weeks - October 15-November 17 2021

The signal is increasing towards the wet bias, it is the drier outlook out of the suite of products and is still showing the wetter bias developing over the north and east but now also increasing the wetter signals for central and southern areas.

CMC Rainfall Accumulation - Next 4 Weeks - October 15 -November 14 2021

Still a wet look for the month ahead, the end of October with widespread rainfall continuing to increase in the forecasts and we are seeing that appear in the short and medium term forecasts.

CMC Rainfall Anomalies - Next 4 Weeks - October 15 - November 14 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. Unlike the GFS, this is picking up on the IOD influence.

CANSIPS Rainfall Anomalies - Next 4 Weeks - October 2021

The wet signal seems well entrenched on this climate model as well, wetter as we go through Spring. Some areas in the green zone over NSW and ACT have seen their monthly rainfall so far. Many areas over the outback of the NT and QLD through northern NSW likely to see rainfall above average during this week coming.


TEMPERATURES

Euro Temperature Anomalies - Next 6 Weeks - October 15 -November 28 2021

This is still the closest to the post for me, cooler than normal back through the southwest and southeast and east with rainfall responsible for the cooler bias over the east and the onshore flow and southwest winds for the SW of WA. Over the north mixed signals, near seasonal values overall for the tropics, however the next few weeks is quite feral weather wise with high humidity. The change in this run has been the warming bias over the interior which may be as a result to the prolonged positive SAM event and increased moisture values moving through the interior for a long duration leading to rain and storms, but marginally warmer weather.

GFS Temperature Anomalies - Next 5 Weeks - October 15 -November 17 2021

Still running really cool for WA and the signal of cooler than normal weather has increased for the southeast and south of the nation in this run. Otherwise the warmer signal continues for the north with soupy air and that may be thanks to the increased chances of a positive SAM event for the remainder of October and into November.

CFS Temperature Anomalies - October 2021

This has flipped to a warm end to the month and start to November with a positive SAM event likely to unfold nation wide.


NOTES FROM PREVIOUS UPDATES FOR REVIEW - FOR THOSE HARVESTING FOR NOVEMBER INTO DECEMBER.

CANSIPS November Rainfall Outlook - Rainfall Anomalies.

The rainfall bias over the north of the nation carries a very high confidence with elevated moisture levels already in place through September and October leading to higher values in November. This moisture is already beginning to circulate south and east through the nation and this sets the stage for widespread falls, particularly over the southeast and east. The remainder of the nation, flip a coin at this stage despite the spread of green on this chart, so for SA and WA, it is conditional upon storm outbreaks and inland troughs.

CFS November Rainfall Outlook - Rainfall Anomalies.

Ignore the drier signals over the northern parts of the nation as that is not likely. The rainfall bias over the southeast and east of the nation carries a higher confidence, interesting that this model continues to show heavier rainfall coming through SA and back through WA with the peak of the IOD. The IOD does appear to be waking up now and influencing the outlook period.

Euro November Rainfall Outlook - Rainfall Anomalies.

This is closest to the post with that moisture over the north of the nation rotating through the upper level winds and moving south and southeast into the eastern inland with high chance of above average rainfall through the northern and eastern states. Will keep an eye on the increasing rainfall chances for SA and back through the outback into the NT, as that has only just started to increase on the forecast charts.

CFS November Temperature Outlook - Temperature Anomalies.

I still think this is running a little cold but it is not impossible given the short and medium term forecasts already issued this morning. Persistent rainfall and cloud cover will lead to lower than average day time temperatures but you may find your night time temperatures will be above average with nature's blanket of cloud in place. The north may see some moderation in relation to the temperatures thanks to more rainfall coming back to the forecast but your humidity values up north will be excessive and this will spread south into QLD and NSW.

Euro November Temperature Outlook - Temperature Anomalies.

This is probably a little closer to the post with the bias of warmer weather over the north of the nation easing back, but I think that is too aggressive and I am leaning toward much warmer conditions over northern areas. The cooler bias over the southeast and southwest continues to hold in most updates. Again we are seeing this reflected in the medium term forecast packages, but interested to see how the nation warms up next week and how high the heat actually is compared to what is forecast. That will tell us a lot about the season ahead.

CANSIPS November Temperature Outlook - Temperature Anomalies.

In good agreement with Euro but I am leaning towards above average temperatures over the north to continue and the cooler bias is expected over much of the south with that cloud cover and widespread rainfall anticipated, we have already begun to see that influence in the past week and this could be repeated time and time again. However it does not mean periods of warmer weather does not develop, it means that the duration of higher heat is less than what we usually see.

ENSO DATA - LA NINA CHANCES - A REVIEW OF THE DATA


The latest data plumes from some global agencies are continuing to come in and they are continuing down the path of a La Nina forming during November and persisting until about February. This will see an increase in rainfall chances (not present on rainfall forecasts here) through December and into much of January to March 2022.


The main areas of impact again northern and eastern Australia, with a focus of an enhanced monsoon, potentially an enhanced cyclone season and storm season over the east and southeast.


With more moisture about the likelihood of above average temperatures and a severe fire season remains very low nationally. There is no evidence in drought conditions developing at this time through more areas of Australia.


Global Modelling - ENSO Predictions.

The plume of models continue to show a strong shift to La Nina conditions with only a few likely to remain neutral. Some agencies are suggesting a longer La Nina vs last year, while other global models suggest a shorter event, these details will be ironed out in coming weeks and the next update.

Dynamic Modelling - ENSO Predictions.

Again a very similar spread from the dynamical models with the shift towards La Nina conditions from November onwards.

IRI/CPC Model Run - ENSO Predictions.

Follow the Red Green and Blue line and they are bringing in a modest La Nina, though NASA continues to be most robust and has not shifted from this stance and based off the observed SSTs, SOI, Trade Winds etc it may not be too far off from the truth so watch this space.

Statistical Modelling - ENSO Predictions.

Again the statistical models are favouring a run of a La Nina summer and like the dynamical modelling, good agreement on the duration perhaps being a little longer than the last event. We wait and see.

As mentioned I will have a La Nina update next week on the 17/18th of October. Summer Outlook on Sunday lunchtime.


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