MODELS AND RAINFALL - AM EDITION

The models are coming back into agreement on the rainfall front, with the southeast looking damp with a better idea of where that rainfall spread will be. However with upper level systems, expect the unexpected this week through southern NSW, southeast NSW, the ACT and eastern VIC as heavy rainfall of 100-200mm is possible anywhere through this broad region resulting in more flooding.


For the north we have got a lower chance now of seeing that monsoon burst that was forecast to come through the continent prior to Christmas, with that energy looking to amplify through the Coral/Pacific Ocean which is good news for the nation to have at least a drier period for the east. Sad for our friends who are baking up north in that unbearable heat. So take a look at that heavy rainfall smear east of the nation and keep watch if it stays there.


The west and far south perhaps continuing dry and a flip into traditional Summer weather.


Lets take a look


SHORT TERM

The main rainfall events through this coming week over the southeast of the nation and the scattered showers and thunderstorms with uneven distribution of rainfall will be the other area of interest.


UKMET - Rainfall Next 7 Days - MODERATE CHANCE

In the short term this is looking close to the post. Rainfall may be a little heavier over the northern tropics, but the confidence of higher rainfall over the southeast of NSW and eastern VIC looks good and the storm activity for the coming 3-4 days over eastern NSW and QLD also looking fairly solid on the data sets. Drier further west through NSW and QLD, into western VIC and then much of SA and WA. The rainfall drawn in for WA is with the hit and miss showers and high heat induced storms.

MEDIUM TERM

The monsoonal burst is likely to jump into Pacific or Coral Seas at this stage, but this idea is not completely set in stone. If that happens, then we will see less rainfall across the nation. If the monsoonal burst comes through the north in the medium term, then we will see higher rainfall across northern and eastern Australia. So there will be a better handle on that coming up from the weekend I suspect. There is still the chance of a tropical low lurking north of Australia but again, know more this weekend. For now, the SAM tending back to neutral will see rainfall frequency and intensity come down for a period before the SAM tends positive again leading into Christmas.


ICON - Rainfall Next 8 Days - MODERATE CHANCE

Has come into line with the other models after being off with the fairies. The rainfall heavier over the east of Victoria and through the southeast of NSW. The rest of the nation is fairly quiet.

CMC - Rainfall Next 10 Days - LOW CHANCE

No change to the guidance over the southeast but the north of the nation is looking very quiet now. The tropical moisture will still be there but the air is divergent and no supportive of widespread rainfall if this is right. But keep watching. The rest of the nation relatively rain free or very little expected.

EURO - Rainfall Next 10 Days - LOW CHANCE

The Euro has come back into line with the other models bringing heavier rainfall through the southeast of NSW and the ACT. It has reduced the rainfall over much of the nation but probably too much. The tropical weather is also looking very limited but again, think this is too dry.

ACCESS - Rainfall Next 10 Days - MODERATE CHANCE

This is not too far from the post I reckon with the heavy rainfall potential under the upper low over the southeast of NSW and the ACT into VIC, potentially bringing very heavy rainfall, especially if the low becomes slow moving. It has passed the monsoonal flow into the Pacific Ocean but some of the tropical moisture with the build up will move south into WA this week and again next week. SA dry is also a fair forecast on current guide.

KMA - Rainfall Next 12 Days - MODERATE CHANCE

Wetter through the east, but it has dropped the tropical low off the NT coast and now placing the monsoonal burst over the Pacific Ocean meaning less rainfall for the northern tropics and then for the majority of the nation which is good news. There could be heavy rainfall for the southeast throughout this period.

GFS - Rainfall Next 16 Days - LOW CHANCE

Probably a little too dry for the nation as a whole still, regardless of where the monsoon goes in the medium term.



ENSEMBLE DATA

These are the useful data sets still and highlight the above commentary. The drier weather over in the west which is seasonal. The east coast also seeing moderate rainfall which is seasonal over the course of the next week. If the monsoon does head east into the Pacific, then below average rainfall may be observed over northern Australia as the flow pattern would steal the widespread rainfall and take it into the island nations to the east.


GFS - Rainfall Next 16 Days (median of 35 members)

It is trending drier and perhaps that is because it is picking up on the monsoon not arriving through the Australian region and going into the Pacific.

CMC - Rainfall Next 15 Days (median of 30 members)

Very good agreement with the Euro in the placement and intensity of the rainfall and storms activity in the coming 2 weeks.

EURO - Rainfall Next 15 Days (median of 51 members)

Note the monsoonal surge over the Pacific and the numbers coming down over northern Australia. Therefore rainfall chances reduce for southern and western Australia and ease for the east.

EURO - Rainfall Next 15 Days Control Member

Note the heavier rainfall over the southeast which is supported by the positive SAM phase.

LONG TERM

Still offering a wet period with the SAM tending positive for the end of December, the monsoonal burst perhaps coming back in January, this combining for wet weather over the east and north.


Euro - Rainfall Next 6 Weeks

More on this in the 6 week outlook coming up from about 11am.

CFS - Rainfall Next 6 Weeks

That wet bias continues for the east and mixed odds elsewhere.

More coming up in your 6 week outlook mid morning.

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