CLIMATE - THE REMAINDER OF SUMMER 2021/22

Lets get straight into it - you can get all the analysis from the video today as there is a lot to unpack. Underneath the video, my forecast charts and analysis charts with a few notes to add of importance

CLIMATE DASHBOARD

A very wet signal across the main drivers, the ENSO and SAM continues to drive the wet weather for the north and east of the nation. The heaviest of the rainfall is being felt at the moment through eastern and northern Australia, which has been the pattern for a while now. The SAM is expected to turn neutral later in the weekend and into early next week but it will tend positive once again, the southern parts of the nation should not see too much change to what we have experienced so far. For the north of the nation, the below drivers are supportive of seasonal to above seasonal rainfall and seasonal temperatures. The MJO is expected to roll into phase across Australia by the end of the month and the first half of February seeing the rainfall increase to very high levels, that will play out across the nation with a deeper moisture profile, this is on top of what has already been forecast in the short term. For SA and WA, the southern areas will remain dry for a while, there will be the odd shower or storm over the coming 10 days and hot temperatures, but the rainfall should begin to increase and the temperatures decrease as we move through this period as moisture from the north begins to creep southwards.

TROPICAL WEATHER

January 8th-Febraury 7th 2022

The MJO is expected to move into the Western Hemisphere with the break conditions experienced over recent days expected to conclude from east to wet across the nation's north. The tropical wave spoken of last week formed into TC Tiffany and that is now in the Gulf. The system expected to move west and continue to dump tremendous rainfall this week and possibly allowing a pseudo monsoon to develop with further rainfall beyond this week. That deep tropical moisture will likely drift towards the Kimberly and become slow moving and subtropics into the second half of the month. Looking at the MJO, it may begin to emerge and move towards Australia by the end of the month, however some members below want to bring the MJO back into the north by as early as next week. The general rule is for it to emerge in the Indian Ocean during early February but I reckon that is a little slow.

SOUTHERN ANNULAR MODE

January 11th-28th 2022

The positive SAM phase is peaking today and tomorrow before it plummets back to neutral conditions by the weekend into early next week, this allowing the moisture to be propelled northwards thanks to a high ridging further north than the past fortnight. This will also disrupt the flow of tropical moisture streaming out of the north and northwest leading to less rainfall for a period over southeast Australia. The SAM is expected to turn positive again for the end of the month which will lead to extensive rainfall and humidity developing again over the north and east of the nation. With the shift in the SAM next week, it may open the door for moisture to stream into WA from the north which may bring some summer rainfall to the SWLD.

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


FORECAST

Rainfall Outlook - Next 6 Weeks - January 11th - February 24th

% chance of exceeding the median rainfall for the coming 6 weeks

A very wet signal continues for the north and east with elevated flood risks for the southeast and eastern inland and through parts of the northern and central interior. The west remains in subsidence and dry air so seasonal weather expectations, though warmer, can be considered a reasonable chance. The wet signal may be increased for northern areas next week as we get a better handle on the tropical weather passing west.

Temperature Outlook Next 6 Weeks - January 11th - February 24th

% chance of exceeding the median temperatures for the coming 6 weeks

A very strong signal for below average temperatures for the east and warmer weather for the west remains a fair forecast with conditions seasonal in between. The persistent easterly flow leading to cloud cover and rainfall over the east and below average temperatures, will run across the nation, drying out and stablaising and combining with persistent high pressure leading to dry and hot weather. This pattern will continue for a good portion of this period but moderation in the hot signal out west will emerge with the development of the monsoon.

Humidity Outlook - Next 6 Weeks - - January 11th - February 24th

% chance of exceeding the median humidity for the coming 6 weeks

High levels of atmospheric humidity is expected to remain in place for the coming 4 weeks at least with only weather signals for a pattern shift over southern areas during later January into early February. At this time, the absence of southern westerly winds, will mean that the weather is expected to remain very humid and soupy for much of the interior, we have experienced that in recent weeks and will see that expand across the central and western interior through this period with rainfall chances to increase in line with that.

Disease Outlook - Next 6 Weeks - January 11th - February 24th

The persistent high humidity and warm wet weather brings about high to major brown rot risks to the food bowl in the east.

Riverine Flood Risk Summer 2021/22

The flood risk is ongoing and continues through the remainder of January into February, and with the wet signal looks to peak in February. The weather has certainly thrown out some high end flash flooding events this week and that is a taste of what is to come for the next 6 weeks. All parts of the nation bar the far southwest of the nation has some degree of risk for the remainder of Summer.

RAINFALL

Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - January 11th - February 24th

No change to the signal with additional heavy rainfall for the north and east of the nation but note the rainfall is spreading southwards through SA and WA with troughs helping to drag the moisture southwards. Showers and storms will return to those areas that have turned dry in recent weeks if not month. Further tropical lows and the monsoon will see a very wet spell for northern Australia over the next 3-4 weeks.

Euro Rainfall Accumulation Control Data - Next 6 Weeks - January 11th - February 24th

Very heavy rainfall in the short term with the remains of Tiffany will dominate the nation's rainfall and moisture supply. The positioning of high pressure with the SAM returning neutral next week will keep the moisture at bay for the short term but it will come south for the end of January and February is looking wet nationally.

Euro Rainfall Anomalies - Next 6 Weeks - January 11th - February 24th

This is probably closer to the post and finally showing the monsoon and tropical low impacts over northern Australia and this beginning to spill southwards over the remainder of the nation. The west of the nation will see further rainfall and SA you should also see rainfall return into February.

GFS Rainfall Accumulation - Next 5 Weeks - January 7th - February 13th

There are signals for heavier rainfall over the north of the nation but the model is handling the tropical weather quite poorly at this time. So keep that in mind.

GFS Rainfall Anomalies - Next 5 Weeks - January 7th - February 13th

This is showing you how off the ball GFS is with regards to rainfall over northern Australia which means that most of the nation's weather is of low confidence regarding rainfall.

TEMPERATURES

Euro Temperature Anomalies - Next 6 Weeks - January 11th - February 24th

This is probably closer to the post, with the west and south drier and warmer, the east and north, cooler and wetter which is La Nina 101. You can see the influence of the monsoon over the north and curiously perhaps moisture and more cloud coming through WA and into SA towards the end of the month and early February.

GFS Temperature Anomalies - Next 5 Weeks - January 11th - February 13th

This model has been running too warm but it is not impossible given the stagnant pressure pattern across the and the absence of the monsoon over the north, however the GFS does not see the tropical low over the north to cool the interior down, so in the absence of tropical weather the nation would warm up.

So what happens after La Nina ends?


This is the preliminary look at the guidance.

% chance of exceeding the median Autumn Rainfall 2022

The chance of exceeding the median seasonal rainfall is remaining elevated over portions of northern and eastern Australia as a direct result of the La Nina waning through the March and possibly lingering into April. It is something to watch as we move through January. If this was to occur, the result would be even wetter weather for the north of Australia with a prolonged wet season, the eastern seaboard will be very wet (especially if the SAM remains positive) and the wet season along the NSW coast which runs from March until June would be equal to what we saw earlier this year, producing those high end floods. The risk is near similar to last year. For the southeast and south, near normal conditions for the season is expected. The beginning of Autumn would likely start out wet but potentially turn more seasonal as we go along. No dry bias is currently strong enough to be drawn onto the charts at this time, but if there was to be a drier location, it would be SA and southern parts of WA. There is no signal for a negative IOD to develop through Autumn at this time however, it is not expected to be anything other than neutral. Conditions remaining seasonal in terms of influence from the Indian Ocean. The Autumn break may not be required, in fact it could be an Autumn break from the rain that we need!

% chance of exceeding the median Autumn Temperatures 2022

Temperatures mostly seasonal throughout though leaning cooler over the east and north. This would be linked to the persistent cloud cover and widespread rainfall developing throughout the nation's north and east and the wet season in both locations to be above normal. The rest of the nation likely to see normal conditions overall with the usual fluctuations in temperature. The guidance still not great this far out to measure the impact of early season cold fronts or cold outbreaks for the south of the nation. At this time, there is no signal of it being early or later than normal.

Rainfall Outlook - Winter 2022

% chance of exceeding the rainfall for Winter 2022

The wet bias from the La Nina through Autumn will wane during the May next year and winter should resolve to near seasonal over eastern areas but coastal communities may still see prolonged colder southeast winds with showers for June before things dry out. At this time, seeing a drier bias for the west of the nation with a persistence of high pressure and a neutral IOD at this time. HOWEVER, there are some models that support the La Nina not quite resolving into winter and there are some models that support the reformation of the IOD into a negative phase. Lets just say this, not El Nino and positive IOD phase is low at this time. Will review this in early January.

Temperature Outlook Winter

% chance of exceeding the median temperatures for Winter 2022

Temperatures at this time, this far out, are leaning warmer than normal, there is not bias towards colder weather at this time, with a few members trending warmer through interior areas, so will placemark this for now. But being this far out, the forecasts will refine during January and February regarding this.

I will have another update on the Autumn and Winter Outlook coming up in the next week, I am working on it, however there is a lot of weather between now and the weekend that needs to be monitored.


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