Jane's Weekly Update: 19th September 2025

To end the week and begin the weekend we have a trough and cold front affecting eastern Australia.

The trough won't be a repeat of the recent, big weather system as it is missing a key ingredient: instability. The big system was a trough and 'cut-off' low that crossed NSW, connecting moisture and instability in a big way. This is missing the low pressure, but southeast QLD and northeast NSW (both west of the ranges) will do the best from this one. However, the rain stretches from Queensland to northern Victoria, and will have embedded storms - and directly under those are locally heavy falls. All of this clears over the weekend.

The southeast feels the brunt of the cold front later on Friday. On the satellite it is the band of cloud over the Bight, with the speckled cloud in behind it indicating the cold air that it brings.

As these weather systems approach, warm and gusty northerly winds are strengthening in the tight pressure gradient that funnels the warm air across the southeast. Yellow areas are at risk of Damaging Wind Gusts - elevated areas from the gusty northerly ahead of the weather system, then add in the coastal areas as the front arrives.

The rainfall potential doesn't have huge totals on it this week, unless you are in western Tasmania, but it clearly shows the areas that will do best from the trough, and how the cold front kicks off a new series of them that should continue well into next week. They will keep coming until the next high pressure system moves in - which it may not have done by the end of next week. This means that forecasts from next Thursday onwards have low confidence at this stage, as the timing from the modelling currently has limited consensus from model to model. Wait for that before you make any decisions.

Meanwhile, the west is in for a stretch of warm and sunny conditions. When the high sits over the Bight, the west is on the warm side of the high. Perth and Melbourne could not be more different over the next week, in terms of both wet weather and temperature.

Looking at the drivers of our weather patterns, and the new monthly guidance is in.

The Pacific Ocean has only one model crossing the threshold into La Nina. But the remainder are all on the negative side of Neutral, and we have a huge pool of warmer than average water off Queensland, so we are set for moisture no matter what the Pacific does as a whole.

The Indian Ocean has reached the peak of this Negative Indian Ocean Dipole (Negative IOD - the "La Nina' of the Indian Ocean). BoM will declare it next week, as they wait until we have been in it for eight weeks - they let you know after the event.

This means we will continue to be fed by moisture from the Indian Ocean - and wherever that runs into low pressure, then those are the areas that get the rain.

Sit back and have all this explained in movement and colour, as I walk you through the above and more in this week's video update. Perfect if you have 13 minutes to spare: