Is climate change to blame for increase in tornadoes in Pennsylvania?
It sounded like a freight train barreling toward his house. I was going to get my wife and go into the basement. We didnt have time, Michael Haggerty said of the tornado that tore through his Doylestown neighborhood last August. (My wife) was in the family room right by the window that got blown away. I just jumped on top of her, Haggerty said. I didnt know what was going to happen. It was gone in 15 seconds. It was that quick.  Quick. And increasingly common, records show. Pennsylvanians have come to expect floods, snow storms, and the occasional hurricane. Now, reports of tornadoes also are on the rise. Some say it's climate change. Others point to residential construction in previously undeveloped areas of the state. Researchers also say tornadoes have to be spotted, and technology has advanced to detect more of the twisters in recent decades. Asked about the number of tornadoes, the National Weather Service said its tracking system wasn't perfect. Tornadoes could have gone unnoticed or unreported in the past. "Temperature and precipitation are collected by instruments that are set out and recording information every day," said  "A tornado requires an observer and knowledge of how to get it into the database." Still, its hard to imagine failure to notice dozens of tornadoes in previous years and across much of the state. Between 2010 and 2020, the National Weather Service had reports of 203 twisters. Thats an 83% increase in the reported tornadoes from the prior decade. Pennsylvania should average 16 tornadoes per year, according to National Oceanic and Atmospheric Administration. Twenty-nine tornadoes were reported 2017. In 2018, 33 were spotted, and 37 twisters were seen in 2019. Last year, Pennsylvania had only 10 reported events. The August 2020 twister that wreaked havoc in Doylestown appears to have started in Bensalem, where it uprooted trees, according to the National Weather Service. Then, it came down in Philadelphia, where it damaged shops and overturned vehicles at the Philadelphia Mills Mall. Only later did it appear in the Doylestown area, according to the National Weather Service. With wind gusts estimated at 115 mph, the twister "picked up and tossed" bleachers on an athletic field at Central Bucks West High School and damaged a day care center at Doylestown Hospital. Six automobiles were "tossed some distance," according to the report. Science offers some theories as to why we're seeing more tornadoes. On April 16, the journal Atmosphere published the study Geographic Shift and Environment Change of U.S. Tornado Activities in a Warming Climate. An increase in tornadoes across a wider swath of the United States could be due to rising surface air temperatures, researchers said. Since the 1950s, researchers have reported the most twisters in the area area that includes Arkansas, Iowa, Louisiana, Kansas, Nebraska, Oklahoma, South Dakota, and Texas, commonly referred to as Tornado Alley, said Stephen Bennett, chairman of the American Meteorological Societys Committee on Financial Weathers and Climate Risk. The recipe for tornadoes requires certain ingredients, Bennett said. Warm, moist air is the base. Then add an unstable atmosphere which causes air to rapidly rise from the ground up to heights greater than 30,000-40,000 feet. Finally, these ingredients must mingle with wind shear.  Twenty years of data from Pennsylvania twisters shows that most tornados occurred in the summer months and during the mid- to late-afternoon. Three-quarters of reported tornadoes occurred between May and September. Most  67%  happened between 2 and 6 p.m., records show. The majority were rated EF0 and EF1 with winds ranging from 65 to 110 mph. Two deaths and 85 injuries were reported in the 20-year period and combined damages were estimated at $121 million. Research is mixed on whether climate change will lead to even more tornadoes in the future, Bennett said. Unfortunately its not yet a clear answer and science has not yet been able to determine how climate change will affect tornado formation, said Bennett. Even so, its certainly possible that a changing climate will nudge the small-scale weather patterns that are so common in Tornado Alley closer to Pennsylvania." Contact reporter James McGinnis at jmcginnis@couriertimes.com