Strange weather quirks seem to protect the Atlantic coast during strong hurricane seasons and less during less-active periods, according to research by a federal atmospheric expert.
A high rate of hurricane activity far out in the tropical waters of the Atlantic Ocean doesn't necessarily translate into a high number of big, powerful storms that could ravage the East coast.
That's one of the key findings of new research conducted by James Kossin, a federal atmospheric research scientist based at the University of Wisconsin in Madison.
The research, published Wednesday in the journal Nature, found that hurricanes swirling toward the East coast of the United States are more likely to intensify during less active Atlantic storm periods, and they are more likely to weaken during more active periods.
While all the reasons are unclear, the research appears to solve some pieces of the puzzle. It shows there are strange weather quirks that help protect the U.S. coast during heavier hurricane seasons.
2016 hurricane season predictions vs. outcome
Kossin found that when the tropics produce many hurricanes -- during long periods of low wind shear and high ocean temperatures far out in the Atlantic Ocean -- they also create a situation where those storms lose energy if they approach the East coast. As the storms get closer to the coast, they encounter a harsh environment of higher wind shear and cooler ocean temperatures, the researcher said.
As a result, those hurricanes end up becoming weaker as they make landfall.
"It's an off-setting factor," Kossin said in an interview Wednesday morning. "It's kind of like Mother Nature creates this environment where a lot of storms are produced (out in the tropical Atlantic). Then she kind of slams the door on them as they approach the U.S. Coast."
That's the trend he found during decades of high hurricane activity in the Atlantic.
"They have to track through a gauntlet of high shear to reach the coast and many of them stop intensifying," Kossin said in a statement released by the University of Wisconsin. "It is a natural mechanism for killing off hurricanes that threaten the U.S. coast."
For people who live in coastal areas of New Jersey and other parts of the East coast, "it is good news," Kossin said. "Greater activity produces more threats, but at the same time, we increase our protective barrier. It's pretty amazing that it happens to work that way."
Pattern showing how vertical wind shear, known as VWS, varies in the Atlantic Ocean. When shear is abnormally low in the tropics, it is abnormally high along the U.S. coast. The lower dashed box shows the tropical Atlantic and the upper dashed box is where hurricanes must pass before striking the U.S. coast. (Courtesy of James Kossin) What was analyzed
Kossin, a scientist for the National Oceanic and Atmospheric Administration's National Centers for Environmental Information who works out of UW-Madison's NOAA Cooperative Institute, spent months analyzing hurricane observations such as maximum winds and central pressure, along with sea surface temperatures and wind shear data, from three 23-year periods from 1947 to 2015.
The first period was from 1947 to 1969 and was the most active. The second was a quieter period from 1970 to 1992, and the third was from 1993 to 2015, which was an active period for major hurricanes.
There were 48 major hurricanes -- ranging in strength from Category 3 to Category 5 -- that made it near the Atlantic coast during the first period, 23 major hurricanes near the coast during the second period, and 35 major hurricanes near the coast in the most recent period.
Kossin said there is solid evidence suggesting the Atlantic basin may be moving back into a quieter period of storm activity, with lower wind shear along the coast. Although fewer hurricanes could be approaching the East coast in coming years, the researcher said, those that do may be stronger and more damaging without the protective barrier of wind shear.
Len Melisurgo may be reached at LMelisurgo@njadvancemedia.com. Follow him on Twitter @LensReality or like him on Facebook. Find NJ.com on Facebook.