MODELS AND RAINFALL - NOW THAT WE ARE DRY, HOW LONG DOES IT LAST?

Now that the weather has dried out for a while and we have lost that major rainfall event on the southeast coast of NSW, we can see better now what is ahead of us in terms of rainfall and the timing of such events.


Lets take a look at the latest data sets for those planning in the short, medium and long term.


SHORT TERM

Looking like most areas will see a big bag of nothing as the air remains dry and stable under ridging. That is good news for those who need to get a dry 2 weeks to finish harvesting their downgraded crops after significant rainfall. The next week at least offers hotter and drier weather with the chance of back to back days of 30C for many areas away from the coastal areas of southern and eastern Australia. We may see a few showers and storms over southeast NSW mid week and over the eastern inland later next week as the troughs redevelop but no widespread severe weather is expected. In the west, cooler with some light showers mid week with a cold front passing through the SWLD. Other areas dry for now away from the tropics.


UKMET - Rainfall Next 7 Days - HIGH CHANCE

Drier weather is expected for much of the nation and only isolated showers and thunderstorms from time to time away from the tropics can be expected in the next week as we take a break from the high rainfall rates.

ICON - Rainfall Next 8 Days - MODERATE CHANCE

Probably too dry but you get the idea of how it is presenting the drier trend across the nation. This highlights no significant rainfall event is expected in the next 7 days.

MEDIUM TERM

Things should start to turn more humid from around next weekend onwards into the week leading into Christmas as has been the guide here for a while. This is as the pressure pattern resets, the MJO moves further towards the east and the moisture can the be allowed to pool over northern and eastern Australia in favourable upper winds. The overall pattern is very typical for Summer and with the increase in temperatures, will mean a more humid airmass will develop than what we have previously experienced, so when the rain and thunderstorms return, they could be even more productive than previous events. So we really need the dry spell to last a fair while and hopefully this can continue beyond Christmas, with La Nina getting itself together.


CMC - Rainfall Next 10 Days - MODERATE CHANCE

CMC brings in more rainfall with a trough passing through SA into VIC and NSW next weekend and then hangs up the trough over the eastern inland of NSW through to the week leading into Christmas with showers and storms most days. Anywhere north and east of here will also become more humid and unsettled as well. Tropical weather increases from later next week into Christmas. The far west remaining dry and warm to hot at times, but there are a few cooler days mixed in to, so no heatwave conditions expected out west like we have seen.

EURO - Rainfall Next 10 Days - MODERATE CHANCE.

Also showing the drier bias for much of the inland with stable air. Rainfall restricted to coastal areas of the nation, especially up over the north and east. Isolated to scattered showers and thunderstorms about at times, but there are no major rainfall events during the coming 10 days which is excellent news. Tropical weather returns in full force from about the 20th of December.

ACCESS - Rainfall Next 10 Days - MODERATE CHANCE

The ACCESS also in alignment with the other global agencies suggesting a reduction in rainfall nationally this week, but is more aggressive in introducing moisture and rainfall chances as we move into the 19/20th of the month and this leading into a humid and unsettled Christmas. That is not out of the realm of possibility with a humid and thundery Christmas, mainly for the north and east at this time.

KMA - Rainfall Next 12 Days - MODERATE CHANCE

Very similar to ACCESS in bringing more moisture and unsettled weather back to the picture for northern and eastern Australia from about next weekend as we run into Christmas. The west should stay dry and warm to hot at times but no serious heatwaves out there at this time.

GFS - Rainfall Next 16 Days - MODERATE CHANCE

Similar to the above ACCESS and KMA in bringing moisture back through northern and eastern Australia with showers and storms increasing from next weekend and running into Christmas but for far southeast and southern areas as well as the west, things may be dry for a while. The tropics staying in build up mode until Christmas but the coverage of storms increases during the festive period and into the end of the month, and that will be where moisture returns to the nations interior and we start the build up to an active January and a very wet February.

ENSEMBLE DATA

Data sets are looking fairly settled on the idea of a drier week coming but the moisture returning through the week leading into Christmas and then heading south and east. The CMC is most aggressive on this idea but it is not out of the realm of possibility as the moisture snaps back over the region and troughs return. There are no major rainfall events in the next 7-10 days.


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

Probably too dry for the interior west of the divide through NSW and VIC but you get the idea of the rainfall spread and where to find it if you need more. The west seasonally dry ahead of the wet season ramping up in January.

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

As mentioned, probably too wet but not out of the realm of possibility if the tropics turn active sooner than what other data sets suggest. This model has picked the rainfall events ahead of time through Spring.

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

Like the GFS too dry west of the divide in NSW and into SA but will review during the coming days. The north turns more active after the 23rd of December and the east coast gets back into persistent and unstable easterly winds about the same time, so I do think these charts will become more colourful as we go along.

LONG TERM


CFS - Rainfall Next 6 Weeks - MODERATE CHANCE

The persistent wet signal continues so the bottom line is, enjoy the warmer drier weather this week because out of the next 6 weeks, 4 of them could be very wet in the east, southeast and over the north with mixed odds back through central and western parts of the nation which will have to watch the tropics closely.

More to come in the days ahead on all things rainfall and modelling, now we have a better idea with the previous rainfall off the board.