The wet signal continues for the north and east of the nation as we track the La Nina through to a peak phase, the Southern Annular Mode being a persistent positive phase and the trapped moisture content in combination with low pressure. For friends out west and through the far south, the weather will gradually become more humid and the return of showers and thunderstorms is a better than 50% chance moving through the second half of this month but a wetter February is likely.
The monsoon is expected to return into the north of the nation for the second half of January with a stronger signal for the NT and QLD, especially with a tropical low expected to move west through the north of the nation delivering heavier rainfall.
The wet signal from the north will then spread south through the remainder of January and persist into February. The tropical weather will remain very active through February which will spawn the cooler and more humid and unstable end to Summer that has been flagged for some time.
Lets take a look
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. Fair warning, the drivers have been supportive of the flash and riverine flood potential for some time for NSW, VIC and QLD and we are seeing that verify. But this is one event of many to come through the regions over the east. 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 around 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. For SA and WA, the southern areas will remain very 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.
January 7th-20th 2022
The MJO is expected to move into the Western Hemisphere with the break conditions experienced over recent days expected to continue for another week or so. Now we have a Rossby Wave expected to move through the region from the east during the next week which may spawn a tropical low which may form a cyclone near QLD and then run west over the nation's north bringing enhanced rainfall. That deep tropical moisture will likely stop short of the Kimberly and become slow moving over the tropical north 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 the middle of the month.
SOUTHERN ANNULAR MODE
January 7th-28th 2022
The positive SAM phase is expected to continue, that means that what weather we have seen this week is likely to be repeated nationally with the wet bias remaining over the north and east and the drier bias over the west and south. There will be an absence of southern ocean westerly winds so there will be little to sweep out the moisture from NSW, QLD and over the interior which means a humid 3-4 weeks is likely with lots of rainfall about.
DATA - Refer to video for more on these sets of data
Rainfall Outlook - Next 6 Weeks - January 7th - February 19th
% 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 7th - February 19th
% 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 7th - February 19th
% 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 7th - February 19th
The persistent high humidity and warm wet weather brings about high to major brown rot risks to the food bowl in the east.
Riverine and Flash Flood Risk January 2022
Flooding is developing for the southeast of the nation and this is expected to expand over QLD and into the NT with a tropical wave stalling out and being absorbed into a trough over the east, with lashing rainfall expected over parts of inland areas. The west remaining fairly dry at this time with not much rainfall expected of any consequence at this time.
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.
Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - January 7th - February 19th
Very wet signal for almost all parts of the nation with significant falls over the tropical north to be expected but over the east, the wet signal is in addition to what has fallen thus far. So this is a critical time for preparations for summer flooding over the eastern and southeastern states. Also rainfall will return to WA and SA as moisture creeps southwards so while it is dry now, the signals are for rainfall to return to much of the nation in line with the La Nina peaking and the monsoon also peaking later this month into February. A wet February is expected.
Euro Rainfall Accumulation Control Data - Next 6 Weeks - January 7th - February 19th
Exceptionally wet weather is expected to develop over the east and southeast in addition to what has fallen over the eastern states so be weather aware moving forward and make preparations for further flooding and severe weather. The monsoonal weather should crank up once again during the latter part of this month into February. Ahead of that, will watch the tropical low potential next week which could enhance rainfall for parts of QLD and NT and this could run south through the nation.
Euro Rainfall Anomalies - Next 6 Weeks - January 7th - February 19th
This very wet phase is expected to continue for large parts of the nation with the La Nina expected to continue and strengthen through this period. Flooding is expected to increase over the east and through the north and expand. The heavier falls is expected attached to troughs over the east with the deeper moisture combination and the tropical weather over the north of the nation attached initially to a few westerly moving waves and the monsoonal flow to follow later in the month into February.
GFS Rainfall Accumulation - Next 5 Weeks - January 7th - February 13th
Very wet signal continues from the GFS for the southeast leading to flood risks increasing. The northern tropics expected to wake up but the GFS has struggled across the board in where to place the tropical weather, which has a major impact on rainfall down stream, as you can see.
GFS Rainfall Anomalies - Next 5 Weeks - January 7th - February 13th
Very strong signals for heavy rainfall over the southeast continue, note the tropical rainfall attached to the tropical lows/cyclones over the north of the nation, which is changing from run to run, but the stronger signal for rainfall is over the southeast and east and drier weather for the west and south.
CMC Rainfall Accumulation - Next 4 Weeks - January 7th - February 7th
That wet bias continues over the north and east of the nation and gradually comes into the eastern and northern portions of SA and through central WA as the moisture creeps southwards. The east coast could see heavier falls than what is advertised here.
CMC Rainfall Anomalies - Next 4 Weeks - January 7th - February 7th
Very elevated rainfall signals across large parts of the nation for the coming 4 weeks. Pockets of the tropics may be a tad drier depending on tropical mischief placement but the southeast and east, very wet weather to continue on top of what has fallen and is falling.
Euro Temperature Anomalies - Next 6 Weeks - January 7th - February 19th
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.
GFS Temperature Anomalies - Next 5 Weeks - January 7th - February 12th
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.
This forecast will be updated again on Tuesday.