The weather has been wild the past few weeks and no surprises there as we verify for those wet and stormy signals that have been present for the 3 months leading into this period.
Now we are dodging systems as they pass through and waiting them out, but how much more is set to come through?
Lets take a look
Rainfall Outlook Next 6 Weeks - November 8th 2021 - December 25th 2021
% chance of exceeding the median rainfall for the coming 6 weeks
We have now started to see the weather that I have been forecasting for months for this period, unfold across northern and eastern parts of the nation and the rainfall and high humidity, severe weather potential and cooler weather is set to continue. For QLD, NSW and VIC, the severe weather from later this week will push through but return again later this month and continue into December, with a very wet run into Christmas. The warmer we get, as we saw through October, that is where the severe weather events will emerge from. The developing La Nina with the waning IOD is the big issue along with the persistent positive SAM. For SA, seeing a taster of what is to come through this period with a deep low combining with copious moisture producing heavy rainfall potential, with many areas experiencing a month's worth of rain in a sitting this week, but some areas missing out, but each major weather event that is coming through is providing severe weather risks and heavy rainfall. This is set to continue right through to Christmas at regular intervals, but the frequency of rainfall not as intense as the east.. For WA, above average rainfall coming in fits and bursts will continue given the moisture rotating through the inland ahead of deepening heat troughs. We are seeing that today and tomorrow, then we go into dry spells, but when it rains through this period, it will be productive and combined with severe weather risks. The tropics - wet wet wet with early season tropical mischief possible with those low pressure systems also influencing rainfall down the line through inland areas into QLD and NSW.
Temperature Outlook Next 6 Weeks - November 8th -December 25th 2021
% chance of exceeding the median temperatures for the coming 6 weeks
We are now seeing the impacts of the higher humidity and increased cloud cover capping day time temperatures over the eastern inland of NSW and into VIC, not cold, but humid and cool. This is the weather you can expect to see across inland SA and VIC and most of NSW and western and central inland QLD as we go through this period. The risk of above average temperatures and heatwaves, very low leading into Christmas. The tropical north should also see a reduction in temperatures thanks to enhanced rainfall and cloud cover.
Humidity Outlook Next 6 Weeks - November 8th -December 25th 2021
% chance of exceeding the median humidity for the coming 6 weeks
Higher humidity values against the average continues to be observed throughout the north and has now shifted into the southeast and east of the nation with the stationary troughs and low pressure lifting this into showers, rain and thunderstorms. The higher moisture content into the medium term will contribute to showers and thunderstorms becoming widespread as mentioned above, however the impacts to crops in the humid and warm weather with the rainfall is now high. The further south and west you go through the nation, there will be breaks in the humidity. The further north and east you go, the longer duration of humidity and warmer weather with rainfall frequent. The guidance remains unchanged from last week which is good for consistent forecasts but not great news for those requiring longer drier spells to get the crops in and better yields, especially over the east.
Disease Outlook - November 8th- December 25th 2021
High humidity and warmer weather coupled with a high risk of above average rainfall and cloud cover will lead to a high risk of disease to crops, especially crops that are in the ground. Vingerons should be on alert for Downey Mildew. Orchardists should be aware of the risk of brown rot and other fungal issues with the higher humidity forecast. Cereal crops ready for harvest also at risk from the myriad of fungal issues as we move into a soupy period. The west sees a lower risk for the SWLD with persistent ridging and onshore southwest winds keeping the weather dry and mild with lower risk of humidity issues for now. All farming operations are likely across the weather situation and should be on alert over the coming 6 weeks - I have already had multiple reports of damage to crops in QLD, NSW and VIC so far this week.
Severe Thunderstorm Risks to Farming Next 6 Weeks - November 8th- December 25th 2021
We are seeing a transition away from the larger hail risk in the short term thanks the deeper and warmer air aloft being of tropical origin, however small scale low pressure systems still offer bursts of severe weather risks with hail in the next 2-3 weeks, but again as mentioned in recent updates, the further we go along in November and December, flash flooding becomes the concern.
Riverine Flood Risk - Next 6 Weeks - November 8th - December 25th 2021
As mentioned last night, this zone remains under a very high risk of flood issues and I will update this chart again next week to include more of QLD and the outback of SA through the NT. But for now this is a huge area of concern through harvest.
Flash Flood Risk - Next 6 Weeks - November 8th - December 25th 2021
We have already observed flash flooding from many outback communities this week from the NT, through northern SA into western QLD and northwest NSW and northern VIC. The risk of flash flooding remains elevated on the current guidance from modelling this morning. Remain weather aware and stay up to date with the short and medium term forecasts in particular through to mid November if you are living in the eastern 2/3rd of the nation.
Large Hail Risk November 2021 - New South Wales and Victoria
This risk offers a lot of anxiety for many in the east and southeast but fingers crossed we transition to the wetter and cooler phase earlier to offset this risk below. The medium term offers a heightened hail risk through to about the 21st of November.
The risk should start to reduce from December, and looking in the medium term, the risk may be peaking during the period from the 8th-21st of November through southern and eastern areas.
All it takes is one storm to cause significant damage - as we saw through the Barossa last week. So you may be sitting in a less frequent rainfall/storm region in SA, but you are residing in a zone where the dry air is wrapping into the moisture and that could see hail risks be increased in future forecasts coming up next week.
No change to the guidance in the climate models once again which is good, the Indian Ocean is peaking in it's negative phase and we are seeing that impact on the overall short and 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 2-3 weeks across the nation. The SAM is currently positive and expected to stay that way, increasing rainfall chances along the east coast as you can see in most data sets below, you will notice the short term forecasts soften the westerly influence from this weekend and tend the winds rapidly back into the east and then that easterly resetting the moisture and stormy weather over the nation for the back half of the month.. Finally the ENSO 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. I know other agencies have said La Nina is already influencing the weather, this is not the case and it is a case of semantics. The influence in the short term is derived from the IOD. This will again be updated on Friday
DATA - Refer to video for more on these sets of data
Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - November 8th -December 25th 2021
A wet and unsettled run of weather is anticipated for the run through harvest into Christmas. All Agricultural regions in the nation will be dealing with elevated humidity, above average rainfall chances and disease risks through this time. I cannot be anymore specific than that, because the risk is so broad. Your rainfall total will vary from place to place given thunderstorms are involved and we have already seen that this week. The further north and east you go through the nation the wetter you will likely be. Flooding is a significant risk for VIC, NSW and QLD plus areas of the outback. This is additional rainfall to come on top of what has fallen - so I just want to point out the very wet signal is set to continue. The tropics getting very active too and tropical mischief may bring deeper moisture over northern and eastern Australia.
Euro Rainfall Accumulation Control Data - Next 6 Weeks - November 8th - December 25th 2021
Significant rainfall of 500mm is possible over parts of the NT and this exceptional rainfall forecast from the data sets will mean rainfall further south and east will be equally wet, well above average with some areas seeing rainfall records set. Note the moisture is now extending further inland of the east coast seeing near record values for much of QLD, NSW and into VIC and notice numbers coming up over SA through this period too and back over WA keeping the above average rainfall for most parts of the nation.
Euro Rainfall Anomalies - Next 6 Weeks - November 8th -December 25th 2021
Exceptional rainfall anomalies above normal continues across vast areas of Australia. This would lead to flood risks increasing through the coming 6 week period leading into Christmas time as mentioned above. Some river systems are already under flood warning in NSW and QLD with flood watches across most states of the mainland. The northern tropics drive the wet weather signal for much of the nation and there will be little breaks in the humidity for the northern half of the nation. The south can expect to feel a humid and wet remainder of Spring and start to Summer.
CFS Rainfall Accumulation Ensemble Data- Next 6 Weeks - November 8th -December 24th 2021
The wet signal continues for much the nation, with that southeast area of NSW and VIC a huge concern for Spring and Summer flooding and the interior parts through QLD and NSW also likely to see significant flood risks too.
CFS Rainfall Accumulation Control Data- Next 6 Weeks - November 8th -December 24th 2021
Heavy and extensive rainfall being forecast for parts of eastern and central Australia but as mentioned in multiple updates the tropical modelling is a weak point in this particular model and something that we need to factor into forecasting. That could mean rainfall totals further south and east may be understated. The bias of heavy rainfall over the southeast again is a fixture on the charts at the moment so if you live in this region pay attention to forecasts. Numbers also coming up over interior parts and the southwest.
GFS Rainfall Accumulation - Next 5 Weeks - November 8th - December 11th 2021
The rainfall totals in the coming 5 weeks are pretty impressive for eastern Australia however the model is an outlier on the drier signal for parts of western NSW and eastern SA but even there, that is about average rainfall for this period! The numbers will likely increase during the coming 5 weeks and I am leaning more towards the Euro solution.
GFS Rainfall Anomalies - Next 5 Weeks - November 8th - December 11th 2021
The GFS is now moving into line with the other modelling, highlighting the southeast, the central interior and northern and eastern parts of Australia as the areas to record above average rainfall. But with the excessive moisture content we are experiencing right now through large parts of the nation leading to heavy rainfall totals, this chart may be underdoing the anomalies in some areas so just be weather aware and understand that some areas could see 1-2 months of rainfall from a thunderstorm which we have seen in scattered pockets from the NT, SA into VIC, NSW and QLD in the past week.
CMC Rainfall Accumulation - Next 4 Weeks - November 5th -December 6th 2021
Rainfall totals in the brown of 100-200mm over eastern areas of QLD through NSW and into VIC is exceptional for a 4 week period, however I will point out that some of the members, triple the rainfall shown here, some of the other modelling is drier in these areas, but the signal is wet for the eastern two thirds of the nation and wetter the further north and east you go. The SWLD of WA starting to see numbers pick up and over the NW of Australia, numbers are also picking up. The tropics, well above average rainfall.
CMC Rainfall Anomalies - Next 4 Weeks - November 5th - December
Highly anomalous rainfall over northern and eastern parts of the nation over the course of the next 4 weeks off this particular product may break records over northern and eastern Australia. These values eclipse last years signal for northern and eastern inland areas lead into the first La Nina phase so this could set up a high risk of flooding for many areas heading into December and Summer in general.
Euro Temperature Anomalies - Next 6 Weeks - November 8th - December 25th 2021
No change in the guidance and again it has been well documented, below average temperatures emerging in line with the humidity and cloud increasing with rain also becoming extensive. If you look at the satellite picture today, that is a taster of what is to come during the next 6 weeks. Sure we will get a few warmer days here and there but more often, cloud will dominate.
GFS Temperature Anomalies - Next 5 Weeks - November 8th- December 11th 2021
The GFS has moved into line with it's sister model CMC showing a cooler bias now across the nation. Still showing the warmer bias over the north which is likely to be in line with the next 2 weeks of weather before temperatures moderate further with rain increasing.
CMC Temperature Anomalies - Next 6 Weeks - November 5th- December 6th 2021
A cooler signal continues under the wetter weather, thick cloud cover and copious amounts of moisture available. This has been a strong signal from this model and continues to lead the way in predicting the wet weather and cooler weather.
I will update this again during Friday but stay weather aware in the short term with the severe weather traversing the nation from today until Friday.