CLIMATE - SUMMER 2021/22 AND A LOOK INTO AUTUMN 2022...WHAT ABOUT WINTER?

Lets have a broader look at Summer 2021/22 and then track forward to Autumn 2022 and then data sets for Winter 2022.


More details to come on the Summer Outlook in 2 weeks today but nice to refresh the data and take a look at the signals into the first half of 2022.


Summer Rainfall Outlook 2021/22

% chance of exceeding the rainfall for Summer of 2021/22.

The development of a La Nina in the Pacific Ocean and the waning of the negative IOD with a persistent positive SAM appears to be the main drivers for a wet and cooler summer for much of the nation. As per last Summer, the impact of a La Nina developing has a higher impact from after Christmas as there is a lag time from the event developing, peaking and waning. That is usually around 2-4 weeks. And so I suspect as per the Spring we have been experiencing, wetter as we go once again seems to be a fair forecast nationally. The monsoon will be very much above average and early this year for the north. That will fuel a deeper moisture profile over much of the nation with the higher chance of rainfall being above the average again, the further north and east you go. For southern coastal areas of SA and WA, conditions could be seasonal with a slight above/below average rainfall bias but from there, as you fan out north through the nation, you find the moisture, the better rainfall and thunderstorms coverage and cooler weather. This has been a significant signal now since I have started this page back in July, that the Spring would be wet, a La Nina Summer would develop and the potential for a very wet end to Summer and start of Autumn is likely.

Summer Temperature Outlook 2021/22

% chance of exceeding the rainfall for Summer of 2021/22.

The cooler bias across the nation does not mean COLD, it means that there is a lower than average chance of exceeding the maximum temperatures. But due to persistent cloud cover, higher humidity and rainfall/thunderstorm chances, the weather is set to be more tropical meaning a humid and sultry summer for many areas is likely. The higher humidity will make it to the southern and eastern coast line regularly with thicker cloud cover, widespread rainfall chances and if that is in combination with onshore winds over the south and east, it could be quite cool. The tropics under enhanced rainfall signal is expected to be marginally cooler than normal overall, but if you live there, you know that the monsoonal breaks can be unbearable hot. We have seen a cold period weather due to cloud cover and rainfall and now this colder snap passing through the southeast, this weather may be replicated multiple times through the season ahead.

STORM SEASON OUTLOOK - REMAINDER OF SPRING

Summer is looking very unsettled for a lot of the nation and we have seen the full impacts of when the high humidity is coupled with very unstable air, the result is large scale severe storm outbreaks and all states bar TAS saw warnings during the last week. More of that to come, especially once we get a stagnant slack pressure pattern dominated by easterly winds. Watching the SAM is going to be key to forecasting these large scale events ahead of time as well as monitoring the medium term data closely as we do most days here.


Severe Thunderstorm Outbreaks - October through April.

The season has been above average over the nation's east and we have seen one outbreak of severe thunderstorms through SA and VIC this week gone with some areas trashed. There is likely to be another outbreak of severe weather in the first week of November across SA and VIC and more severe weather expected across QLD and NSW. This season is not going to simmer down all of a sudden. I am afraid that many areas are to impacted by severe weather through the harvest and then into early next year. With the La Nina developing, we may lose the hail risk with more moisture in a saturated warm atmosphere, but the flooding risks go through the roof as we head into the first part of 2022 as we saw with last Summer, the east coast and adjacent inland flooded and severe weather impacts elsewhere further west and north.

Risk of riverine flooding - December through February

This chart represents the chance of flooding and potential disruption for outback areas in particular. Now you don't have to see rainfall falling overhead to be impacted by flooding, with the Darling River for example flooding upstream but can impact communities deep into NSW as we have seen throughout this year. The higher values exist over northern and southeast Australia, as has been the expectations since July. The weather over the southeast carries a high risk of disruption, with major river systems at 100% capacity and saturated catchments. These areas are sitting ducks to flooding, especially along the Murray River, even though the catchments have had a break in the past 2-3 weeks which has been a godsend. Over the north, the flooding could start early through the wet season, from December onwards. Elsewhere, excessive convection and persistent unsettled weather could see the flood risk increasing in the next two weeks, especially with near record rainfall for parts of the outback of the NT and WA.

Bushfire Risk - December

The higher humidity with elevated rainfall chances for much of the nation will decrease the risk of fire danger throughout the east and southeast. Though lightning risks will always start fires in the nation so be weather aware, even in the rare chances of the dry thunderstorm activity during this period. The west drying out and with excessive undergrowth underway with the very wet year will spark an elevated fire risk especially into the New Year.

Fire Risk Outlook - January 2022

Similar risk values for the southeast and southwest with risks increasing through Tasmania during January as the weather dries out further throughout the state with the mainland keeping most of the above average rainfall. The weather over the southwest likely to bring a medium risk of fires this year with a little more humidity than normal for early 2022 drifting southwest and south into the west coast trough. The only risk with the fires through the southwest will come from dry thunderstorms that do ride the Scarp and the southwest inland coastal areas from time to time.

Fire Risk Outlook - February 2022

Signals for a drier February are increasing a tad for the south and with the elevated rainfall from spring and early summer, there are chances that this part of summer may see fire risks increase over the southern pockets of WA, VIC and TAS. The risk again connected to mainly lightning with thunderstorms moving through.

Remember that only 5% of fires are started by nature and the most devastating fires are human driven by accident ignition. So we have everything going for us environmentally to have a relatively low risk fire season.


CYCLONE OUTLOOKS - NO CHANGE IN THE GUIDE

The number of named storms through the north of Australia has remained unchanged since the last guidance with expectations the season will be some what above normal in most regions. The next update on this product is in two weeks.

Cyclone Risks - Usual expectations of the impacts from cyclone activity.

This chart represents the areas that have major direct impacts from cyclone activity, whether they are passing by over the north in open water or through the inland with rain and storms with flooding potential. The impacts seasonally are far reaching. We could see some tropical cyclone activity in the coming 2-3 weeks. This year with the amount of cyclone activity being forecast by global agencies suggests we could see quite a bit of rainfall as the main issue to deal with this year. The next update on this product is in two weeks.

I will be updating the tropical weather in 2 weeks time.


RAINFALL ANOMALIES

December 2021

December will continue in the same vain as much of Spring, the wet bias over the southeast inland, through the eastern inland and over the tropics. The residual impact of the Indian Ocean Dipole negative event continuing to stream moisture in from the northwest will be in place until about Christmas and then that impact will begin to ease. For the north and east, the tropical waters around Australia are well above average presently and this will continue into Summer. The Coral Sea of great interest, already indicating the La Nina phase, the waters east of QLD are well above normal and are forecast to remain this way and spread south to be off the NSW coast during Summer. Every time the winds veer into the east over NSW and QLD, the showery weather will be productive and heavy. We saw this last Summer, the inability to dry out between major rainfall events and the flooding was therefore more extensive and severe because of the persistent rainfall. For the southeast of the nation, December will be humid, unsettled and this may extend into parts of Ag SA, but once again the better rainfall odds are over in the east. For the west, seasonal conditions, but as we see this week coming, it takes one event of rainfall to push many areas above the average, so the above average rainfall while impressive is not as significant as above average rainfall in areas where it is the wet season, like the tropics, which look very active from now onwards.

January 2022

The nation generally wet and humid, unsettled with persistent troughs through inland areas of the nation. The troughs lifting areas of deep moisture over QLD, NSW and VIC. The wet bias over in WA could be an expression of the above average wet season and potential tropical activity, that element no model can forecast ahead of time. The NT has brown over it, I would not read too much into that, again one tropical cyclone/low and the average for the month is taken care of. For much of the nation, high humidity, more rainfall than normal is a fair chance in most states and this will offset the high heat potential for many inland areas.

February 2022

Wet weather increasing from January to February. The wet signal thanks to the monsoon over the north of the nation and the peak in the easterly wind dominance over the nation causing the rainfall chances to be elevated over much of eastern and northern Australia, stretching down into the southeast, helped along by weakening frontal weather from time to time. We average about 1-2 fronts per month in summer for southern areas. For WA, it is near seasonal and that is normal, however a rogue tropical system can cause this forecast to be quite useless. Otherwise the trend of the Summer getting wetter as we go is in line with what occurred last season, regardless of the model data below, as this has not factored in the La Nina phase.

SEASONAL OUTLOOK - SUMMER 2021/22

So you can the nation is in green with pockets of heavier rainfall opportunities for the east and north. Significant risk of wet season flooding for the north is likely, over Cape York, the NT and through inland WA and the outback. Flooding risks increase for areas of eastern Australia with the wetter signal kicking off from January but more likely through February. The remainder of the nation, seeing more frequent rainfall events that normal which will see more humidity mixed in with the warmer weather, it is going to feel fairly tropical this Summer. Storm season active, severe storm outbreaks also higher than normal for much the north and east of the nation. This will pose an issue for a range of industries and has already caused some issues thus far, early into the season.

SEASONAL OUTLOOK - AUTUMN 2022

The seasonal outlook for Autumn is looking wet as well, and this could be a hangover like we saw last season from the wet summer. I am leaning towards March being wet and then things starting to dry out as we go through April and into May. We are getting way out there, but thought for forward planners and those wanting to know what is lurking out there, yes there is further wet weather into Autumn with a prolonged wet season thanks to a lingering La Nina. The drier bias over QLD is unlikely under this guidance if a La Nina has formed and declared, plus this data set supports a developing negative IOD once again.

TEMPERATURE ANOMALIES

December 2021

Cooler bias from Spring, it continues in the east for December as the higher than normal rainfall continues to dominate the north and east. We have lost that bias of warmth over northern Australia thanks to more rainfall and cloud cover by December. The rest of the nation, normal conditions are expected, that will see warm to hot weather, interspersed with periods of milder weather with onshore winds as systems move through west to east over the southern states. If you are living in the east and north, the humidity will be off the charts at times so be aware, you may be under blue, that does not mean comfortable values.

January 2022

The cooler bias over the east wanes a little bit, but increases over in the west of the nation and this could be due to tropical activity and perhaps persisting ridging or troughing, a range of reasons for this. Given the rainfall bias being above normal through the region, I would be thinking it is more to do with the moisture increase coupled with inland low pressure. For the remainder of the nation, seasonal, values could be below average over the north with the above average wet season so that is conditional. Otherwise if you don't like heat and want rainfall, this is looking good for you.

February 2022

The seasonal bias continues for much of the nation as the members struggle to extend the life of the La Nina. Some of the data sets has the La Nina persisting through to the end of March while others resolve it by January into early February. Regardless what models struggle to do is verify the impacts this far out, so while it is looking benign, it may be a case of higher humidity and higher rainfall with seasonal temperatures. The higher the temperatures, the higher the moisture levels, the higher the cloud cover and rainfall.

Seasonal Outlook - Summer 2021/22

The nation is looking fairly seasonal for the majority of Summer. Once again the bias of cooler weather linked to where the rainfall is more frequent, the cloud cover more extensive and where onshore winds dominate. That does appear to be the east still and through portions of the west and possibly up across the northern tropics. The rest of the nation, a humid and seasonal Summer.

Seasonal Outlook - Autumn 2022

The cooler bias will persist into Autumn with more rainfall through the March keeping things cool. Sometimes March can be a blistering month of weather but at this stage, it could be that we get an early break under the influence of more tropical moisture and the return of cold fronts moving north, picking up that moisture, as we saw this past Autumn. Something to watch. The tropics being wetter than normal for the end of the wet will impact the temperatures over the nation with more cloud cover passing over inland areas, snuffing the heat engine from getting too hot and sending the hot air southeast. I will review the Autumn Outlook in greater detail in mid December once we see how the La Nina is handled by the global models and agencies.

AUTUMN OUTLOOK PRELIMINARY FORECAST BASED OFF THE ABOVE DATA.

A sneak peek at the Autumn Outlook for 2022. This forecast clearly is a low confidence forecast but the data sets have been trending cooler and wetter as a lag influence from the La Nina. Also some chance of another negative IOD next year as well.


Rainfall Outlook - Autumn 2022

% chance of exceeding the rainfall for Autumn 2022

The residual impacts of La Nina that forms over Summer will persist into March of 2022 and as we saw with the last event, the rainfall was heaviest through February to April on the east coast and the above average rainfall continued over the northern parts of the nation. Now not one event is ever the same, but the current data sets below support the rainfall remaining heightened over these regions through Autumn, especially March and April. The weather will start to dry out with some confidence over southern and western parts of the nation as the rainfall focus moves north and east. The Indian Ocean is expected to remain neutral through next year with the positive forecast from the BoM model indicating the impact of the monsoonal season. Some climate agencies support another negative IOD developing through winter but there is little skill in forecasting that driver ahead of time.

Temperature Outlook Autumn

% chance of exceeding the median temperatures for Autumn 2022

The temperatures will continue to be seasonal to below seasonal for much of the nation, again with the ongoing impacts of the active monsoon, higher than average SSTs over the northern and eastern parts of the nation with prevailing winds pumping moisture inland, producing more cloud and rainfall chances. The southwest of the nation may start to see a warmer end to Summer with elevated temperatures continuing into March and April. With the higher than average humidity forecast over the northern and eastern areas of the nation, the day time temperatures may be marginally warmer than normal. Nights will likely be above average for much of the nation with above average rainfall, humidity and cloud coverage.

WINTER 2022

There are a lot of people out there who like to claim they can read the crystal ball and forecast specifics so far out, it is not possible, but what you can do is have someone who is trained to take a look at the data sets and give you advice as to where the signals are taking us. I could make a forecast and that forecast come off, but there is NO SKILL in that! And it would be wrong to offer such a service! The weather does not work like that and neither does weather forecasting. But lets see what the SIGNALS are.


Taking a brief look at Winter 2022

Seasonal Outlook Winter 2022

The rainfall guidance is vague this far out but you can see mixed odds on the rainfall through the nation. Perhaps a drier west of the nation but the east may persist with wet weather. Noting the IOD remains neutral to negative on the climate models from May through August next year. Not seeing any drought signals developing in the guidance yet.

Seasonal Outlook Winter 2022

The temperatures are seasonal, which is good to see this far out, some years we can see very warm signals on these climate products. At this stage it could be the third year in a row of seasonal temperatures for the nation. But again, being this far out, it is more of analysis than a forecast.

More details on the harvest outlook as many continue to get operations underway again, coming up Tuesday and a La Nina update during Wednesday.










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