 Activity was primarily suppressed by significant weakening of the Atlantic Ocean thermohaline circulation ( THC ) early in the year , representing the largest reduction in strength of the THC since NCEP / NCAR Reanalysis began . The weakening of the THC was possibly the result of lowered ocean salinity and a decrease in North Atlantic Deep Water formation . Oceanic and atmospheric gyres were able to strengthen in the subtropical Atlantic , allowing southward advection of cold air and water . Consequently , there was a significant cooling of sea surface temperatures over portions of the north Atlantic . This resulted in a continuation of the spring weather pattern over the Atlantic Ocean , with strong vertical wind shear , mid @-@ level moisture , and atmospheric stability . The weak THC resulted in slightly stronger low @-@ level trade winds , an increase in upper @-@ level zonal winds and vertical wind shear , higher environmental air pressures and less low @-@ level mass wind convergence and rainfall in the Intertropical Convergence Zone , and reduced middle @-@ level moisture . Collectively , these factors worked to suppress tropical cyclogenesis . 
