2017-2018 South Pacific tropical cyclone outlook: Northern Australia at highest risk for landfalls
The South Pacific tropical season is expected to bring a near-normal number of cyclones to the Australian Basin; however, a high percentage of these cyclones is expected to impact land.
“This tropical season is expected to be quite similar to last season across the basin,” according to AccuWeather Senior Meteorologist Jason Nicholls.
“An early start to the season is expected once again with a named cyclone forming before the end of December,” said Nicholls.
AccuWeather meteorologists are forecasting 10 named tropical cyclones between 1 November 2017 and 30 April 2018. This is slightly below the historical average of 11 named cyclones.
Out of the 10 named tropical cyclones, four or five are expected to become severe tropical storms with winds of 118 km/h (73 mph) or greater.
“The forecast is for two or three of these severe tropical cyclones to make landfall in Australia this season,” said Nicholls.
“In addition, several tropical lows could develop throughout the season, bringing additional flooding to northern Australia,” said Nicholls.
A beach-side house is destroyed in Tully Heads, Australia, Saturday, Feb. 5, 2011, after Cyclone Yasi brought heavy rain and howling winds gusting to 186 mph (300 kph). (AP Photo/Rick Rycroft)
A positive Southern Oscillation Index and variable water temperatures will be two of the biggest factors in tropical development this season.
The Southern Oscillation Index is based on the observed sea level pressure differences between Tahiti and Darwin, Australia.
A positive Southern Oscillation Index correlates to an increased risk for tropical cyclone development to the north and northwest of Australia along with an increase in land-falling cyclones.
Cooler-than-normal waters off western Australia are expected to warm during the season bringing the greatest threat late in the season to these areas.
Meanwhile, warmer-than-normal waters off the northern coast of Australia and in the Coral Sea throughout the season will be a positive factor for additional cyclone development.
For these reasons, the number of land-impacting cyclones is expected to be above normal with six impacts over the course of the season.
“There may be a lull in cyclone formation in January before the peak of activity occurs during February and March,” said Nicholls.
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