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Cyclone risk ‘elevated’

Saturday November 15, 2014 Written by Published in Weather
Cyclone risk ‘elevated’

8 to 12 cyclones expected in Southern Cook Islands

 CYCLONE SEASON is upon the South Pacific, and this year the southern Cook Islands are being warned to expect “elevated risk”.

Regional weather agencies have collaborated to issue a tropical cyclone outlook that predicts above-average activity for the southern Cooks, Samoa, Tuvalu, Tokelau, Niue, and New Zealand.

Vanuatu and New Caledonia – countries that generally experience the region’s highest levels of cyclonic activity – are less likely than normal to be affected during the 2014-15 season.

Cyclonic activity is likely to be low during the first half of the season, but to increase from February onward. Experts predict cyclogenesis – the birth of a cyclone -- will generally occur between 12 and 14 degrees south. Cyclones tend to move poleward as they develop.

As a whole, the region should expect “near average tropical cyclone numbers”, specifically between eight and 12, and probably about 10. Based on data recorded between 1981 and 2010, the Southwest Pacific experiences an average of 12.4 tropical cyclones per season.

Forecasters expect a weak El Niño to develop over the course of this season. El Niño – a period of climactic variation that occurs every few years – heralds warmer sea surface temperatures and generally means above-average cyclonic activity for the Cook Islands. Presently, the region is in a neutral phase of the ENSO (El Niño Southern Oscillation) cycle, but that could change.

“Close to neutral conditions exist at present for both equatorial sea surface temperatures and the atmospheric circulation in the Southwest Pacific, although indications of El Niño have been building lately,” reads the outlook report. 

Bearing this prediction in mind, forecasters used data derived from years characterised by similar conditions to compile this season’s report.

At least four storms are predicted to reach Category 3 strength, or wind speeds of at least 64 knots or 118 km/h. Three are expected to reach Category 4 strength, with wind speeds of at least 86 knots, and though no Category 5 predictions have been publicised, “this type of event is still possible”, the report says.

“While there is a low likelihood of a Category 5 system occurring, recent analogs suggest this type of event is still possible, and therefore this situation cannot be ruled out.”

In recent years, scientists at the fore of the global climatology community have been making murmurs about climate change making a definitive impact on tropical cyclone activity. Data is still sparse, but well-respected researchers have created models that suggest cyclones will increase in intensity, if not in frequency, as a result of global warming.

The Southwest Pacific’s cyclone season officially opened on November 1, and will not conclude until the end of April. Communities of people on Manihiki, on Rarotonga, and in New Zealand ushered in the sombre season on November 1 with prayer services commemorating the 19 people lost during Cyclone Martin in 1997, the deadliest disaster in recorded Cook Islands history. Martin hit unexpectedly, on the first day of the regional cyclone season, much earlier than usual.

Arona Ngari, director of the Cook Islands Meteorological Service, warns the Cook Islands community to be on alert over coming months. He reminds the general public to treat every warning as if it’s real, even if the warnings preceding it turned out to be false alarms.