Its that time of the week so lets have a look at the coming 4-6 weeks and see if there is any easing of that wet signal which looks to be highly disruptive for parts of the east and southeast. The weather over SA and WA is more variable and there is a lower chance of exceeding the average rainfall through this period, does not mean you won't, but less chance.
For temperatures, cooler than normal for many locations over the southwest, south and eastern inland while the north will be feral under high humidity and above average temperatures.
More below (this video could be 45 minutes long - however to find the data sets and charts, read the notes on this video underneath).
% chance of exceeding the median rainfall - October 8-November 21 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. All 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 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 (here anyway while other agencies keep much of the west and central areas in the wet bias). Flooding is a risk over the southeast during this period after flooding in recent weeks. 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.
% chance of exceeding the median temperatures - October 8-November 21 2021
Cooler bias continues for the southwest and eastern inland of the nation and that is largely unchanged from previous forecasts. The north of the nation soupy under very humid and sultry air and the early build up, however the values may begin to moderate as more clouds and rainfall develops through November and some chance the north could trend below average, especially if the monsoon comes in earlier. Otherwise, the ground temperature over the south of the nation will take a while to warm up IF the rainfall and cool bias continues.
No change to the guidance in the climate models, we know the Indian Ocean is negative phase, the ENSO region (which I will discuss soon) is heading towards a La Nina phase and the SAM is trending negative this week but likely to remain neutral with little impact or influence for the nation during the coming 2 weeks. 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 data verify in my opinion.
DATA - Refer to video for more on these sets of data
Euro Rainfall Accumulation - Next 6 Weeks - October 8-November 21 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.
Euro Rainfall Anomalies - Next 6 Weeks - October 8-November 21 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.
CFS Rainfall Accumulation - Next 6 Weeks - October 8-November 21 2021
Very wet signal continues from the CFS, no change in guidance.
GFS Rainfall Accumulation - Next 5 Weeks - October 8-November 14 2021
Rainfall largely unchanged from run to run, though placing a heavier bias over the east coast, some models 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.
GFS Rainfall Anomalies - Next 5 Weeks - October 8-November 14 2021
Interestingly 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 2 weeks. The remainder of the nation should see seasonal conditions and wet through southeast Australia, ignore that brown shading.
CMC Rainfall Accumulation - Next 4 Weeks - October 8-November 7 2021
That is quite a wet look, 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.
CMC Rainfall Anomalies - Next 4 Weeks - October 8-November 7 2021
Very wet look, and it is increasing each update. The west I suspect will dry out over time.
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 8-November 21 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 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 8-November 21 2021
This is running really cool for WA which may be a bit of copy cat action going on with the strong cold front next week being replicated a few more times over the region, this happens from time to time on GFS. Otherwise the warmer signal continues for the north.
CFS Temperature Anomalies - Next 6 Weeks - October 8-November 21 2021
Cooler signal over much of the nation is in response to the wetter signal from the climate data sets and this has remained unchanged for the past 4 weeks and has verified for the most part.
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.
I will have a look at November shortly and at the bottom of that post you can find details on the La Nina chances for Summer 2021/22 which may ramp up the wet signal for the east and north for the coming 6 months.