WA surfers are waxing their boards in anticipation of a rare “superbomb” in the Southern Ocean, which could reach our coastline as soon as tonight.
The meteorological phenomenon will result in 3m swells in the South West which, though not unusually arge, in size, will be more powerful and travel much faster than typical summer swells.
Forecasters refer to a powerful low pressure system that drops in pressure by 24 hectopascals (hPa) or more in 24 hours as a “bomb” or “bombing low”. A weather system twice as powerful as a bomb is referred to as a superbomb.
According to surf forecasting agency Swellnet, WA will from Sunday night start to see the swell from a superbomb – the first since 2007.
It has been generated by the interaction and merging of two former tropical cyclones in the Indian Ocean – Ava, which struck Madagascar last week, and Irving, which tracked south-east from Mauritius.
The resulting mega-storm was too far away to affect WA’s weather this week but the swell generated by it has travelled hundreds of kilometres to reach our shores.
“When two volatile and energy charged cyclones combine… the end result can only be something of significance,” said .
He said the resulting storm had been forecast to drop “a phenomenal 47hPa in 24 hours at a latitude of 40-45 degrees south” which meant it would “fall into the superbomb classification, which is very rare”.
“The last time I can recall a system like this locally was March 2007 – almost 10 years ago – when the Bureau of Meteorology issued their first-ever hurricane wind warning for southern Australian waters,” Swellnet’s Craig Brokensha said.
Mr Brokensha said the superbomb had generated “storm-force” winds that would result in “large long-period surf ranging from Sumatra (in Indonesia) to southern Australia”.
In Perth, the waves will be much smaller at around 1.3m, with much of the swell blocked by Rottnest Island and offshore reefs.
Surf forecasting service Coastalwatch said WA’s South-West would receive most swell, while South Australian beaches would also feel the effects of the superbomb.
Bureau of Meteorology forecaster Luke Huntington said his team had not monitored the so-called superbomb because the weather system played out so far from WA and did not affect the state’s weather.
But he agreed a 3m, long-period swell was due to reach WA’s South-West capes tonight and into tomorrow.