Goodbye La Niña...for now
With the signal weakening in the equatorial Pacific Ocean, La Niña has officially come to an end.
That 'signal' being cooler water over the eastern Pacific and warmer water to the west. Currently, the sea surface temperatures are warming in the east, while below the surface, a pool of warm water is pushing from west to east, quelling the source of deeper cool water that was being upwelled through spring and summer.
We're now expecting a few months of neutral conditions, however, there's a 50% chance we'll see a double-dip La Niña developing through spring.
With the signal weakening in the Pacific this doesn't mean the swell potential for the East Coast (the biggest benefactor of La Niña) is done for.
In fact, the opposite is true. Over the coming months, warm water in the Coral Sea is due to feed south into the Tasman Sea owing to the East Australian Current. Meanwhile, over in the Indian Ocean we've got an even more pronounced pool of warm water that's flowing down the Western Australian coast via the Leeuwin Current.
This is where things get interesting. During the autumn and winter months, cold air (from southern latitudes) is projected further north, where it meets warm water, providing the catalyst for cyclogenesis. These mid-latitude systems are better suited to the East Coast, as in the southern states they bring close-range, windy swells which fade by the time conditions improve. Let's hope we see a good mix of proper Southern Ocean frontal activity mixed in with the expected mid-latitude lows. This is more likely into the winter months.
For the East Coast, cyclongenesis is much more ideal, with East Coast Lows, Tasman Lows and other variations providing plenty of quality surf, much like last year. That is if you fall north of the low's axis. Any location to the south will simply get battered by gale-force onshore winds, storm surf and heavy rain.
Over the next couple of weeks the main impact on our local weather and surf will be the Madden Julian Oscillation (MJO), that being the wave of increased tropical activity that impacts Australia during summer and autumn.
The MJO is currently strengthening and moving across our north, bringing an increase in tropical instability, and this will be the catalyst for the low forming in the Coral Sea off the Queensland coast through Friday.
It looks like we'll see a pattern of supporting highs sliding through the Tasman Sea, supporting any troughs/lows that develop, thereby producing plenty of easterly swell for south-east Queensland and northern NSW. Depending on where the low tracks, southern NSW will pick up a bit of size though onshore winds will be an issue.
The southern states will see those funky mid-latitude lows messing with local winds and conditions while also bringing close-range swell energy, mixed with pulses of groundswell.
For a more up-to-date run down of the outlook for the coming months, tune in to the regional Forecaster Notes.