Active Atlantic hurricane periods may not produce intense hurricanes that threaten the U.S. East Coast. This phenomenon owes it to the protective shield formed by cooler ocean temperatures and vertical wind shear at the East Coast of United States, which helps in weakening the intensity of incoming hurricanes.
This was revealed in a new research published in Nature.
The research was conducted at the University of Wisconsin-Madison by James Kossin, a federal atmospheric research scientist at the UW.
He studied the relative intensity of hurricanes in the low and high Atlantic hurricane periods by factoring in many unstudied elements.
New Approach
In the research, Kossin pursued a novel approach, departing from the traditional focus on tropical Atlantic as the chief hurricane development region by pulling in hurricane-producing conditions outside that region.
Cooler sea surface temperatures work in conjunction with faster wind shears to produce hurricane seasons.
That is why the intensity of hurricanes is ascertained by tracking ocean temperatures and wind shear.
Kossin's research extrapolated the incongruity of hurricanes formed in the Atlantic basin getting weakened upon landfall. To explain this anomaly, the scientist explored other patterns and dug up past data to establish related patterns.
He studied the data spanning from 1947 to 2015, which gave information on location, central pressure, and maximum winds. Also, the data from the National Centers for Environmental Prediction and the National Center for Atmospheric Research had a benchmark of sea temperatures and wind shear of the sample period.
Kossin inferred that even as tropics produce hurricanes when they hit the U.S. coasts, an erosion of energy takes place after being stonewalled by higher wind shear and a cooler ocean temperature.
"They have to track through a gauntlet of high shear to reach the coast and many of them stop intensifying," said Kossin.
In fact, he calls it a natural mechanism that kills hurricanes threatening the U.S. coast.
Weakening Of Protective Barrier
This also implies that during quieter periods in the Atlantic basin, lower wind shears will take away that protective barrier at the coast. That is why Kossin is cautioning that even if fewer hurricanes may be lashing the coast during that low period, they can be stronger and come under category 3 to category 5 range.
The study has been able to explain why there has been no major hurricane attack in the United States for more than 11 years.
Kossin also mentioned that Hurricane Matthew has proved the existence of a protective barrier from the mix of strong crosswinds and cool coastal waters. Matthew fizzled to 75 miles per hour when it lashed South Carolina. It had a devastating speed of 145 miles per hour when it passed by Haiti.
