15 named storms predicted
A ‘well above average’ 2008 Atlantic basin tropical cyclone season has been predicted by two prominent forecasters from Colorado State University.
Scientists Philip Klotzbach and William Gray released their spring long-range forecast Wednesday, predicting 15 named storms, eight hurricanes and four major hurricanes.
Compared to their long-range forecast from last December, the pair increased their predictions of the number of named storms, hurricanes, and intense hurricanes from 13, seven and three respectively.
‘The current sea surface temperature pattern in the Atlantic is a pattern typically observed before very active seasons,’ the scientists’ forecast report states. ‘Waters off the coast of Iberia as well as the eastern tropical Atlantic are very warm right now.’
In addition, the report notes that a weather pattern known as the Azores High was very weak during the month of March.
‘Typically, a weakened Azores High leads to weaker trade winds that enhance warm [sea surface temperatures] anomalies due to reduced levels of evaporation, mixing and up-welling in the eastern tropical Atlantic.’
One factor that could help inhibit hurricane development in the Atlantic is the El Niño/La Niña phenomena in the Pacific Ocean. In La Niña years – when Pacific sea surface temperatures are cooler than normal – there in usually increased Atlantic tropical storm activity.
Last year and into this year there has been a moderate to strong La Niña pattern in the Pacific Ocean, however there as been a warming of those waters in recent months.
‘The big question is whether this current observed warming will continue through this year’s hurricane season,’ the forecast report stated, adding, however, that none of the models are predicting a switch over to an El Niño event between August and October of this year.
If not for the uncertainty of what will happen with the sea surface temperatures in the Pacific, the forecast would likely have called for even more tropical activity in Atlantic this year.
‘If current trends in the Atlantic persist, there is a possibility that the forecast could be increased more in early June.’
Klotzbach/Gray state that their forecasts are based a statistical methodology derived from 58 years of past data and a separate study of analogue years which have similar precursor circulation features to the current season.
The two scientists – as well as many other long-range tropical activity forecasters – have come under criticism in recent years. Klotzbach and Gray severely under-predicted 2005’s record breaking tropical activity and they over-estimated the 2006 and 2007 seasons.
The two make no excuses and remain committed to the exercise.
‘We have not been ashamed of our forecast failures,’ the report states. ‘It is the nature of seasonal forecasting to sometimes be wrong.
‘You always learn more when your seasonal forecast busts than when it verifies. Busted forecasts drive us to explain the reason for the failure and likely lead to enhanced skill in future years.’
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