MODELS AND ALL THINGS RAINFALL.

I have just got the power back and internet after the vicious storm whipped through this afternoon, much cooler and about 50mm of rainfall here in Darwin.


The tropics certainly waking up today as advertised, also some wild storms about the ACT and southeast NSW, as advertised. More inclement windy wet weather for the east coast with the remains of Seth, things have verified fairly well. The west and south still remaining largely dry which is also expected.


Lets look very quickly at all the models and rainfall.


I want to make these points before consuming the data sets.


  1. The tropics will dictate a lot of the rainfall in the medium term, any cyclone that forms and makes landfall will clearly dictate the heavier rainfall. Where that occurs, no one knows, not even the models but you can see the ideas on the table.

  2. The placement of the trough over the eastern and southeast inland during the week coming will determine where the heaviest of the rainfall will end up. As per above, you can pick out where the trough is on each of the models displayed and there is divergence in ideas.

  3. La Nina is still yet to peak and the influence from that should start to be felt in February, we are yet to reach our wettest time of the sequence.

The data will move around and my current classification can be found above each of the models. There is no point in writing large synopsis's for each as the data is constantly changing run to run.


SHORT TERM

The trough over the southeast and east and the rainfall increasing over the northern tropics, these areas will see rain. If you are not in these areas, then you are dry for a while with high pressure nearby.


UKMET - Rainfall Next 7 Days - MODERATE CHANCE

MEDIUM TERM

The trough over the east remains and we see it link up with the tropical moisture over the northern tropics. The weather then seeps southwards from the north into Central Australia then into the south and southeast creating an environment for more showers and thunderstorms, severe weather risks and high humidity. Widespread additional rainfall is also possible for large parts of the southeast and eastern inland which may lead to flooding. Rainfall may also move into eastern SA but far southern WA may remain dry for a while. A developing tropical low or cyclone, maybe two, over northern Australia will form the focus of heavier rainfall sweeping the nation IF they indeed do form and then travel southeast and southwest over land and into troughs over the east.


ICON - Rainfall Next 8 Days - VERY LOW CHANCE

CMC - Rainfall Next 10 Days - MODERATE CHANCE

EURO - Rainfall Next 10 Days - HIGH CHANCE

ACCESS - Rainfall Next 10 Days - MODERATE CHANCE

KMA - Rainfall Next 12 Days - MODERATE CHANCE

GFS - Rainfall Next 16 Days - MODERATE CHANCE

ENSEMBLE DATA

The broader data sets are following the forecast I made in December for this period, wetter over the north and the east with a very sharp gradient the further west and south you are from the troughs over the north and the east. However, the wild card to always watch in Summer are the tropical lows. These are the features that can bring about the heavier inland rainfall, one system can be all it takes for some areas over arid Australia to get 1-2 years worth of rainfall. This does occur in La NIna.


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

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

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

EURO - Rainfall Next 15 Days (Control Member) - HIGH CHANCE

I am leaning most with this solution.

LONG TERM

Longer term as mentioned it gets a whole lot wetter and so now is the time to make preparations. My forecast for the 6 weeks ahead is due out tomorrow.


CFS - Rainfall Next 6 Weeks - MODERATE CHANCE

More details to come - there are a few items on the board that need to be carefully monitored.