That is due to the tropical weather which is continuing to evolve on all modelling, but each model treating the monsoonal flow differently meaning that the distribution of moisture and rainfall potential which impacts temperatures, changes from run to run.

This continues to be the case, so this is a short update to show that.


Moisture Watch Next Week - December 10-17 2021

Moisture clearly heaviest over the north of the nation and extending through to QLD and NSW with onshore winds and showery weather to continue there. The moisture from those easterly winds then propelling moisture inland through NSW and then drawn into VIC. The remainder of the south and west looks drier than normal for this period with the easterly winds dominating and the emergence of the monsoon up north, that will help to push moisture east and southeast throughout the nation rather than south and west at this time. The GFS does want to introduce a broad cloud band connected to a cyclone but that is in voodoo land and moves that system from one location to another from run to run.

Rainfall Next Week - December 10-17 2021

Rainfall confidence remains low as mentioned and using the ensemble/broader data sets are more useful to track the trends in the modelling overall. The rainfall bias continues to be over northern and eastern Australia with the heaviest falls now appearing over the far north of the nation and through pockets of eastern QLD and NSW. The inland areas may see a reduction in rainfall potential, but this could swing back depending upon the evolution of the tropical weather. The drier weather is anticipated to be over western parts of the nation where high pressure will be setting up shop and extending along the southern portions of the nation trough to SA.

Rainfall Anomalies - December 3-17 2021

Rainfall anomalies unchanged on the current guide and we could see the rainfall anomalies trending above average extend further south through WA and the NT depending upon the evolution of the tropical weather. In the east, the ongoing showery easterly winds will keep the wetter signal going and the persistent inland troughing also keeping the rainfall in place for the eastern inland of QLD and NSW dipping into VIC. Drier weather expected for southern SA and into WA.

Temperature Anomalies Next Week - December 10-17 2021

Temperature anomalies are expected to follow the same script with hotter weather for the west of the nation spreading east through the outlook period, the duration of this again dependent upon how long it takes for the tropical weather to whip up. The cooler than average weather overall, will continue for parts of the east in those onshore conditions. You will find a decent increase in heat values nation wide ahead of the tropical weather increasing and then the monsoon developing. Nature's air-conditioning.

DATA - Refer to the video for more details.

18Z GFS Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

The cyclone activity now relocating from Darwin, to be north of Port Hedland! It will shift again next run and the impacts down stream into the east and southeast is reliant upon where the monsoonal flow enters and where the system goes in the medium term. Ahead of that, two low pressure systems to deal with over the eastern inland with further rain and thunderstorms and dry in the west and through the south.

18z GFS Precipitable Water Anomalies - Next 16 Days

Moisture over the north of the nation is dictating the rainfall potential throughout the nation and this will chop and change run to run, I wish I could be more useful.

18z GFS Rainfall Accumulation - Next 16 days

This carries a low confidence.

12z CMC Rainfall Accumulation - Next 15 days

This carries a low confidence

12z Euro Rainfall Accumulation - Next 15 days

This carries a low confidence

More details to come this afternoon.