During periods of greater Atlantic hurricane activity, a protective barrier of vertical wind shear and cooler ocean temperatures forms along the US East Coast, weakening storms as they approach land, according to a new study by NCEI scientist, Jim Kossin.
In his paper, “Hurricane Intensification along United States Coast Suppressed during Active Hurricane Periods”, published in Nature, Kossin identifies this “buffer zone” and describes its relationship with both active and inactive periods of Atlantic hurricane activity.
“During periods of greater hurricane activity, the sea surface temperatures are warmer and the wind shear is weaker in the tropical Atlantic,” says Kossin. “Likewise, during periods of low activity, the sea surface temperatures are cooler and the wind shear is stronger there. But, the opposite is true when we look near the US coast. When conditions in the tropical Atlantic are good for hurricane intensification, they are bad for it near the coast and vice versa.”
So, when the environment is good for making strong hurricanes in the tropics, those hurricanes crash into more hostile conditions if they approach the US coast, which weakens them. In this way, the pattern creates a hurricane buffer zone along the coast during periods of high activity.