Jane's Weekly Update: 9th May 2025

May isn't likely to deliver much needed rainfalls, but things look slightly better as we go into winter and spring.

The Sea Surface Temperature Anomaly (SSTA) shows we have warm yellows in the Indian Ocean box, but there are warm yellows and reds near Australia, providing a source of moisture. The Pacific Ocean box was a cool blue over summer, and is now neutral, but there are warm yellows and reds near Australia, providing a source of moisture.

This map shows that we have plenty of moisture to play with.

In order to make it rain you need that moisture to feed low pressure - our lows, troughs and cold fronts. The Southern Annular Mode (SAM) is Positive, and has been for the majority of the last year. That stops cold fronts from coming up from the Southern Ocean, and can encourage high pressure to be dominant across the south blocking any low pressure from entering.

This near continuous Positive SAM is one of the main culprits for the ongoing drought in much of the southeast. Troughs and lows work with moisture from the tropics to produce rain, but the high pressure blocks them from coming into the red areas:

May is essentially a write-off if you are after rain in the south. The modelling for the next few weeks indicates that high pressure is going to continue to dominate.

Next week brings rain to the east coast in onshore winds, and there is a bit of activity up north - not pushed into the south as high pressure blocks it.

Things look slightly more promising as we go into winter.

The outlooks for June and June through to August show more green on the map. That indicates that feeds of moisture are able to work their magic - but look closely at where the green is - it isn't over the southwest or southeast. Instead these areas are no longer strong brown, but more of a neutral 50/50.

For the full details, don't miss my latest video update: