Tropical Storm Risk (TSR), which provides real-time mapping and prediction of tropical cyclone windfields worldwide, is pleased to announce the release of their extended range forecast for North Atlantic hurricane activity in 2015.
Based on current and projected climate signals, North Atlantic basin tropical cyclone activity in 2015 is forecast to be about 20% below the long-term (1950-2014) norm and about 30% below the recent 2005-2014 10-year norm.
- An ACE (Accumulated Cyclone Energy) value of 79. The long-term and recent 2005-2014 norm values are 102 and 113 respectively.
- A 24% likelihood that activity will be in the top one-third of years historically, a 32% likelihood it will be in the middle one-third of years historically and a 44% chance it will be in the bottom one-third of years historically.
A key factor behind the TSR hurricane outlook is the anticipated enhancement of the July-September 2015 trade wind speed over the tropical North Atlantic and Caribbean Sea. This enhancement arises from anomalous longitudinal gradients in surface air temperature associated with the projected anomalies in summer 2015 El Niño Southern Oscillation and tropical North Atlantic sea surface temperatures. An enhanced trade wind speed will suppress hurricane activity by acting to increase vertical wind shear, decrease cyclonic vorticity and cool tropical North Atlantic SSTs.
It should be stressed that forecast uncertainties at this extended (December) lead are large. The precision of TSR’s extended range hurricane outlooks between 1980 and 2014 is low.
To access the full (pdf) forecast document, including an assessment of the precision of publicly issued seasonal North Atlantic hurricane forecasts for 2005-2014 as a function of lead time, please click here.
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