BoM warns that cyclone season could be worst in 27 years

Cruisers planning on sailing in tropical regions this summer should be prepared to run for a cyclone bolt-hole at short notice and batten down the hatches — hard. Nor should those further south be complacent because the fall-out from cyclones may extend further south than normal.

The Bureau of Meteorology has warned that a La Niña event in the tropical Pacific Ocean and high Southern Oscillation Index could result in the worst cyclone season for 27 years, and also a season starting up to two weeks earlier than normal.

"The Southern Oscillation Index is strongly positive this year and is a significant factor in the number of cyclones in the Australian region and the likelihood of an early cyclone in the Indian Ocean, Timor or Arafura seas," said Ian Shepherd of the Bureau’s Darwin office.

"The forecast number of tropical cyclones in the Australian region in the 2010-11 season is in the range 17-22, compared with 12 in an average year.

"The season we are drawing a parallel with is 1998-99 when Cyclone Thelma threatened Darwin in early December, but luckily didn’t hit the capital city.

Cyclone Thelma was one of the most intense tropical cyclones (a Category 5) to be observed off the coast of Australia and the most intense cyclone to threaten Darwin since Cyclone Tracy in 1974.

"In the Northern Territory monsoonal activity normally starts around Christmas and the first cyclone not long afterwards, but this year you can expect it a couple of weeks earlier and that will go for the Indian Ocean as well."

Normally the cyclone season starts on November 1 and ends on April 30 and the cyclone belt runs from Shark Bay north and east in WA and from Brisbane north in Queensland, including all the coast of the Northern Territory. However, another downside of an La Niña event is that fall-out from cyclones can extend further south.

"While the damaging effects of tropical cyclones do not impact NSW very often, they are more likely to occur in La Niña summers," the manager of the NSW Climate Services Centre, Clinton Rakich, warned.

La Niña is the flipside to the well known drought-producing El Niño, In addition to causing higher sea temperatures and increasing the Southern Oscillation Index and risk of cyclone, La Nina events usually also bring wetter than average spring and summer conditions to much of eastern Australia. Sydney, for instance, can expect half the number of days above 35 degrees when compared to El  Niño years like last year.

Dozens of yachts were damaged and wrecked in Shute Harbour in the Whitsundays in March of this year when the Category 3 Cyclone Ului hit the region, with some owners failing to take simple precautions such as moving their boats to a secure marina or up sheltered mangrove creeks or removing sails from on deck. Even prior to Cyclone Ului some insurance companies were refusing to cover boats left on moorings. Another aspect of the aftermath that made the event even more distressing for boat owners was that some of the boats tossed ashore were looted.

Cruisers can obtain at least three days’ notice of possible threats by visiting the Bureau’s website, www.bom.gov.au/cyclone/outlooks/index.shtml Phone updates for each state could also be obtained from an automated service. Visit the website to check for your state’s number, as these vary.

- Caroline Strainig, Editor, Cruising Helmsman magazine

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