MODELS AND ALL THINGS RAINFALL - THE MONSOONAL FLOW IMPACTING RAINFALL FORECASTS THIS EVENING.

There are no surprises with the chopping and changing in terms of tropical weather, the placement of the monsoon, the placement of tropical lows and potential cyclones, meaning that from one run to the other, the rainfall forecasts are a hot mess. The weather will remain volatile in terms of rainfall for the next little while, so you may be forecast for 200-300mm one run down to 10-20mm the next. It is that type of weather.


That poses another issue surrounding tracking severe weather potential, with high impact systems emerging within days of occurring, and when you are dealing with flooding and the potential for further heavy rainfall in the coming 2-3 months remains high, it is quite a dangerous time.


Lets take a look at the latest information.


SHORT TERM

Short term offers some relief from the rainfall over the eastern inland of the nation with a reduction in the low pressure leading to less showers and thunderstorms about but they will still be around. The tropics are likely to see showers and storms increase while the rest of us are dry.


UKMET - Rainfall Next 7 Days - MODERATE CHANCE

As mentioned above, while there is rainfall over the east, the coverage is less widespread and less heavy. The focus may now be shifting into the northern tropics and that moisture then extending southwards through next week depending on the placement of a trough. This is more aggressive than other models on that idea.

MEDIUM TERM

Models remain low confidence with the monsoonal potential playing havoc with all models and as mentioned, the placement, development, scale and depth of these unstable winds will determine who gets what and when and there is no skill at this time to predict such things. Just ideas on the table that will refine as we go through next week.


ICON - Rainfall Next 8 Days

Dry, way too dry but it is picking up the moisture over the north and eastern inland but way too dry.

CMC - Rainfall Next 10 Days

CMC continues to have trouble placing the monsoonal flow but it is still showing it. The east unsettled tomorrow and over the weekend and next week and over the western interior from mid next week as that moisture increases from the north into the west coast trough. Relatively dry for the south.

EURO - Rainfall Next 10 Days

Even the Euro struggling with the rainfall over the east with it moving from VIC through to NSW, now it is into QLD. The remainder of the nation will see a fairly humid airmass develop but there is little defined trigger now in this run for a major rainfall event. The northern tropics starting to pick up on that monsoonal flow from as early as the end of the period.

ACCESS - Rainfall Next 10 Days

This is clearly the most aggressive on the spectrum with the moisture being drawn into troughs and lifted into widespread rainfall and thunderstorm activity across the nation's north and east and this could be picking up on a pattern we have seen from Spring being repeated in this product. We will have to watch as this would result in more flooding.

KMA - Rainfall Next 12 Days

Still like ACCESS, wet and most aggressive with the rainfall placement and development through the medium term in relation to the monsoonal flow. Has a prolonged storm outbreak for the east but as you can see it is not well supported in this idea.

GFS - Rainfall Next 16 Days

As mentioned the GFS will move the tropical feature from run to run, tonight it has it over the east of the NT, earlier it was south of Indonesia, then over the Pilbara. It will be different in the morning have implications on rainfall spread.

ENSEMBLE DATA

Still the most useful weather sets through these uncertain times. The weather is clearly going to get wetter over the north with the approach of the monsoon and over the east there is a high chance of further rainfall events. The deterministic data above will reflect this in the coming days, but it is going to be very low confidence until then. These data sets more useful


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

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

Showing that monsoonal weather a bit more tonight than this mornings run

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

The weather is getting wetter on the charts as we see the monsoonal weather descend and the east coast remain quite unsettled so do expect the forecasts to chop and change.

LONG TERM


GFS - Rainfall Next 5 Weeks

Still very wet with the monsoon and that moisture running down south and east throughout the nation especially in the week leading into Christmas to New Years.

More details coming up from 7am EDT tomorrow

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