Colorado State University scientists Philip Klotzbach and William Gray have lowered their forecast of tropical cyclone activity in the Atlantic Basin in a report issued Tuesday morning.
The main basis for the downgraded forecast of tropical cyclone activity is the development of an El Niño event, which involves a warming of sea surface temperatures in the tropical Easter Pacific Ocean.
The Klotzbach/Gray report noted the El Niño is expected to intensify over the next few months.
‘El Niño events tend to be associated with increased levels of vertical wind shear and decreased levels of Atlantic hurricane activity,’ the report stated.
The two scientists now forecast there will only be five hurricanes in the Caribbean basin this year, down from six in their 9 April forecast and down from seven in their 10 December 2008 forecast. The five hurricanes prediction is about one below the statistical average for a year.
Klotzbach and Gray are also predicting 11 named storms, down from the 12 they forecast in April and from the 14 they forecast last December. Their prediction of two major hurricanes of Category 3 strength or above remains the same as it was in their April forecast, but is one fewer than the three they forecast in December.
Although they predict a below average year in terms of the number of tropical cyclones in the Atlantic Basin this year, Klotzbach and Gray do not think it will start a new trend.
‘Although we have been in an active multi-decadal Atlantic Basin era since 1995, it is not unusual to have a few below-average years within an active multi-decadal period,’ their report stated. ‘Likewise, it is not unusual to have a few above-average years within an inactive multi-decadal period.
‘We expect the active Atlantic hurricane era that we have been in since 1995 to continue for the next 10 to 15 years.’
Tropics heating up
Despite Klotzbach and Gray’s downgraded forecast in expected tropical cyclone activity this year – which the National Hurricane Center in Miami is expected to follow when it releases its August forecast tomorrow – the Atlantic Basin is by no means out of danger yet.
Statistically the most active part of any hurricane season in the Atlantic Basin runs from August through November, with the peak in the second week of September.
In 2004, the year Hurricane Ivan wreaked havoc on Grand Cayman, the first tropical cyclone did not reach the strength to be named until the first day of August. The season ended up producing 16 named storms including nine hurricanes and six major hurricanes of Category 3 or above. Four of those major hurricanes – Charley, Frances, Ivan and Jeanne – made landfalls.
In addition, an El Niño event does not mean there will be no major hurricanes. In late August during an El Niño year in 1992, Hurricane Andrew became one of the most powerful storms ever to make landfall in the United States when it came ashore in Homestead, Florida and later in southwest Louisiana.
Cayman’s Head of Meteorological Services Fred Sambula said just because there was downgrade in the forecast of tropical cyclone activity this year, it was no reason to lessen vigilance.
‘All it takes is one,’ he said. ‘If it doesn’t happen, we can all say we’re grateful to God.’
Mr. Sambula said the current sea surface temperature in the region was about 30 degrees Celsius, well above the 26 degree-Celsius threshold needed for tropical cyclone development
Mr. Sambula said El Niño events do statistically reduce Atlantic Basin tropical cyclone activity.
‘That’s proven scientifically,’ he said. ‘But it doesn’t mean there will be no tropical cyclones or that you don’t have one with your name on it.
‘This is the hurricane season; anything can happen. We still have to keep our fingers crossed.’