A QUICK WRAP OF THE MODELS AND ALL THINGS RAINFALL

Model madness continues with all agencies placing the heavy rainfall smear in different locations in the east, the potential for follow up rainfall also on the cards, but once again models treating that system different from run to run and from agency to agency.


Throw in some tropical mischief as well over the northern waters and you have yourself a dog's breakfast.


Many scratching their heads in the east and south with one set of data on the old trusty yr.no showing 100mm one run to 10mm the next. The model data generally is low confidence but the key is consistency across the board and looking at all the data, not just one particular small data set.


The high confidence can be found in the follow, the further north and east you go through the nation, the wetter you will be.


Lets take a look


SHORT TERM

The short term models all intialise the system over WA into SA tonight, no problem. It is from here that the models struggle with the direction the low pressure system takes, in relation to the high building to its south. If the high builds further south and flattens the ridge, the system will move through southern NSW and northern VIC with heavy rain. If the high ridges more firmly and northwards, then the system will be bumped further north through central and northern NSW with next to no rain for Ag SA, most of VIC and southern and southeast NSW where rainfall prognostics have been much heavier. The overall confidence in any one solution is low but for consistency I am sticking with the low adopting a track over southern and central NSW and existing the NSW coast between Katoomba and Canberra. This will change again tomorrow. The rest of the nation is settled, the tropics are turning more active and the west of the nation turns dry. QLD remains more unsettled as we go as moisture pools in onshore winds and troughs develop over the interior.


UKMET - Rainfall Next 7 Days - LOW CONFIDENCE

MEDIUM TERM

The medium term offers more model madness. The lead low moves out to sea and then a secondary trough deepens over the west and central parts of the nation, picking up moisture and taking scattered showers and storms east into QLD and NSW mainly. The trough does seem to adopt a easterly track at this time, helped along by a developing ridge over WA into SA. This can still and will likely change as the lead system will dictate how this secondary feature evolves over the NT and northern SA into the eastern states. There are a whole range of solutions on the board so it will take a few more days to work this feature out, but watch it closely if you are living in QLD and NSW. Otherwise tropical weather over the northwest and north of the nation may become have an influence of pumping moisture deep into the nation with troughs lifting this up over northern and western interior portions to see showers and storms return. And tropical easterly winds increasing seeing showery weather with moderate falls over northern QLD, that moisture feeding troughs over southern inland QLD and northern NSW with further rainfall chances. There is a lot going on.


ICON - Rainfall Next 8 Days - LOW CHANCE

CMC - Rainfall Next 10 Days - MODERATE CHANCE

Based on consistency from run to run.

EURO - Rainfall Next 10 Days - LOW CHANCE

Been very inconsistent, however if this idea of increasing rainfall over central areas continues and this lead system moves further north in the new data set in the morning, then I will adjust my forecasts accordingly. The rest of the nation has seen good consistency otherwise.

ACCESS - Rainfall Next 10 Days - MODERATE CHANCE

Again has been fairly consistent in placement of rainfall.

KMA - Rainfall Next 12 Days - LOW CHANCE

Has fallen into line with the CMC, ACCESS AND GFS but consistency renders it low chance.

GFS - Rainfall Next 16 Days - LOW CHANCE

Most aggressive on the tropical activity at the moment. Rainfall over the SE of the nation has been most consistent inline with CMC, ACCESS and KMA. The others are outliers. But watching the Euro closely.

ENSEMBLE DATA

These data sets are diverging now, which expresses uncertainty, so the low confidence period of weather will last a number of days.


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

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

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

LONG TERM

The consistent feature tonight is the persistent wet signal through to early January.


CFS - Rainfall Next 6 Weeks - MODERATE CHANCE

The wet signal continues for the east and north and noting the tropical rains are emerging on the charts (this model does not cope with the tropical data sets)

Full update again from 7am EDT.

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