Updated: Jul 28
I am afraid that we are moving into a tricky period of weather, of course as many of you know who have lived on the land, this is not uncommon and is expected as many roll the dice and gamble on when to get the crops out and hope that severe weather potential does not eventuate over your properties.
I wish you all the very best of luck as you make preparations.
Lets look at the data - notes follow underneath.
% chance of exceeding the median rainfall next 6 weeks - October 12-November 24 2021
The wet bias continues for much of the nation's north and east and is likely to increase in coverage and intensity during this period. The global modelling indicates a strengthening of the wet bias over the north, outback, into the eastern inland of QLD, NSW and the ACT dipping into northeast VIC. The IOD also appears to be having some influence now in the coming 2-4 weeks and showing up on the medium term. The rainfall guide continues to show the chances of exceeding the rainfall tapers off the further west you go through the nation where much of the SA Ag areas sit in the flip of the coin region which has been the case for much of this year. Flooding is a risk over the southeast during this period after flooding in recent weeks, there are flood watches over NSW and likely to be issued for VIC later this week.. These same catchments are likely to receive above average rainfall during this period. The topics quite active, we will see that this week with more coverage on that....hope you like tropical weather coverage, as that will impact rainfall moving through the warmer months into early next year. The west could see some above average rainfall with the storm season kicking off earlier over the SWLD and the influence of the IOD has now lead me to just shade in green over the Ag areas in response to above average rainfall chances next week.
% chance of exceeding the median temperatures next 6 weeks - October 12-November 24 2021
No change from Friday though I have expanded the threat of cooler than average weather now through southern interior parts of the nation and broadened the cooler bias over the western interior. The north is likely to see moderation in the warmer bias in the coming updates.
No change to the guidance in the climate models, we know the Indian Ocean is negative phase and we are starting to see that impact on the overall medium term forecasts with moisture streaming in from the northwest. The ENSO region (which I will discuss soon) is trending towards a La Nina phase and the SAM is trending negative neutral with little impact or influence for the nation during the coming week however it may turn positive at the end of the month. We need the SAM to move positive for the rainfall to verify along the east coast and adjacent inland - this is key to seeing the below forecasts from the climate models being wet and humid and cooler for much of the nation. We have seen one system already verify these conditions and there are signals for more to follow in the medium and longer term.
DATA - Refer to video for more on these sets of data
Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - October 12-November 26 2021
Very wet signal continues, the control member ramps it up even further. 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. Severe weather from thunderstorm activity also needs to be reviewed in the coming weeks with damaging winds, large hail and flash flooding all an above average chance against seasonal averages.
Euro Rainfall Accumulation Control Data - Next 6 Weeks - October 12-November 26 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.
Euro Rainfall Anomalies - Next 6 Weeks - October 12-November 26 2021
The Euro is increasing the rainfall for the period, as per the climate drivers, the IOD 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.
CFS Rainfall Accumulation Ensemble Data- Next 6 Weeks - October 12-November 26 2021
Very wet signal continues from the CFS, no change in guidance.
CFS Rainfall Accumulation Control Data- Next 6 Weeks - October 12-November 26 2021
Some very heavy falls of 200-300mm possible if this is right through inland NSW and northern VIC. That is a flood forecast if that verifies but will watch trends.
GFS Rainfall Accumulation - Next 5 Weeks - October 12-November 14 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 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. So there are some indications of major weather systems for the south and east. SA and points west, less likely to see excessive rainfall but seasonal rainfall looks a better than 50% chance for the east. WA will see a reduction in rainfall frequency over the SWLD however now with the influence of the Indian Ocean, if the rains come, it could be productive and heavy.
GFS Rainfall Anomalies - Next 5 Weeks - October 12-November 14 2021
The signal is increasing towards the wet bias, but still the deterministic is signaling drier than average conditions for the east coast, where the climate component which runs off a different set of parameters says not so fast! Watch the low pressure dominance over the east in the coming week. The remainder of the nation should see seasonal conditions and wet through southeast Australia.
CMC Rainfall Accumulation - Next 4 Weeks - October 12 -November 82021
Still a wet look for the month ahead, the cropping pastures will bumper under such guidance for the east and south with this rainfall expected and soil moisture near saturation in the southeast. But the flood risks are increasing for the southeast as a consequence under this monthly forecast. We have a chance of flooding returning to VIC and TAS this week with a low pressure system.
CMC Rainfall Anomalies - Next 4 Weeks - October 8-November 7 2021
Very wet look, and it is increasing each update. The west turning wetter now in the latest outlook for the medium term too.
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.
Euro Temperature Anomalies - Next 6 Weeks - October 12 -November 26 2021
This is 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. That higher humidity will assist in promoting cloud cover over the south and east leading to the below average signals, especially if low pressure gets involved.
GFS Temperature Anomalies - Next 5 Weeks - October 12-November 14 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.
CFS Temperature Anomalies - Next 6 Weeks - October 12 - November 11 2021
Cooler signal over much of the nation is in response to the wetter signal from the climate data sets and we can see that colder signal strengthening over the western interior, perhaps more cloud bands about.
CANSIPS Temperature Anomalies - Next 6 Weeks - October 8-November 21 2021
The cool bias continues for the east and southeast of the nation and across the southwest. Note the cooler "blobs" over inland areas of QLD and SA, that signals that inland rainfall and heavier convection that normal is quite possible through this period. Also the north of the nation will be warmer than normal as per other modelling with the early build up.
A LITTLE FURTHER AHEAD - 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
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. I will have a seasonal outlook for Summer 2021/22 on Friday.