Closing in on cyclone forecasts
Feared for their unpredictable nature and immense power, tropical cyclones have the capacity to devastate tropical communities. It's estimated 10,000 people per year die from tropical cyclones, while the associated wind, rain, swell, and storm surge can cause widespread damage to infrastructure and crops.
Between lives lost and the cost of damages, the need to better understand cyclones is compelling. The old adage of 'forewarned is forearmed' means an early warning system can save lives and property.
To date, the best science can offer is a pre-season outlook per ocean basin, heavily weighted by probability and statistics. For instance, on average four cyclones per season form in the Coral Sea with the BOM saying there was a 65% chance of fewer during season 2019-20.
As it happened, there was just one, TC Gretel, so the Bureau was correct but the information is too vague to be of much use.
This week, University of Newcastle in collaboration with New Zealand's National Institute for Water and Atmospheric Research, announced a new predictive model called Long-Range Tropical Cyclone Outlook for the Southwest Pacific (TCO-SP).
Here at Swellnet, we were informed about the model via an ABC article that made it sound almost too good to be true. Cyclone swells are notoriously hard to forecast, yet TCO-SP could allegedly forecast them better than swells from everyday lows and highs. Of course we were excited.
Yet it pays to adopt a skeptic's position. The claims were indeed too good to be true. A fact we discovered after speaking to lead scientist Dr Andrew Magee. No, the model couldn't forecast cyclones from years out, nor could it predict the exact track of cyclones - which is the aspect that tickled us as forecasters.
However, surfers won't be entirely disappointed with the capability of TCO-SP. After describing how the model works, Dr Magee said the South West Pacific basin - often treated as one region by weather agencies tracking cyclones - is treated as eleven "island-scale" regions in the new tool.
TCO-SP creates specific forecast data for eleven regions. It does so to narrow down warning information - Cairns and Rarotonga are both in the South West Pacific basin but at 6,000kms distant one size does not fit all.
Compartmentalising the region will help Queensland and northern NSW surfers. The best swell-producing cyclones usually form well off the QLD coast near New Caledonia or Fiji and remain distant from the mainland, thereby enabling a large spread of groomed swell free of meddling winds.
If, as Dr Andrew Magee claims, TCO-SP can tell us how many cyclones will form in the New Caledonian region, or the Fijian region, then we're heading towards something tangible. Still with many moving pieces in between outlook and realisation, but closer than we currently are.
Expectations can be further narrowed with TCO-SP giving monthly updates, as opposed to the BOM's lone cyclone prediction every October.
It's all theory at present, but come November we'll be watching TCO-SP very closely and marrying it up with actual cyclone swell.
There's a slightly perverse element in using TCO-SP to predict good surf - it was, after all, created to save lives and economies. Yet almost all the tools we use in modern surf forecasting have their roots in safety. Surfers are fortunate in that we (mostly) don't rely on them for safety but can utilise them for leisure.