On a quiet afternoon in September 2021, Chris Erdner and her husband were at home in Montgomery County, Pennsylvania, when an urgent warning flashed on their television screen. The remnants of Hurricane Ida had sparked a tornado in their area, and residents were being told to seek shelter immediately. The couple rushed to their basement, and moments later, they heard the unmistakable roar of a tornado passing directly over their home.
“I don’t know if you’ve ever heard it,” Erdner said, describing the noise. “It sounds like a freight train.” Though the storm lasted only a few minutes, the destruction it left behind was extensive. Large trees were uprooted, power lines were downed, and some of her neighbors’ homes were severely damaged. One house lost its entire second floor. When the storm passed, Erdner and her husband emerged to find their street in ruins. “We walked up and down the street, as did all of our neighbors, just checking on each other to make sure everyone was OK,” she recalled.
The tornado had caused $10,000 in property damage to Erdner’s home, but she considered herself lucky. A woman just half a mile away lost her life when a tree fell onto her house. “It’s strange, what tornadoes do,” Erdner said, noting that while her house was still standing, others in the neighborhood were nearly destroyed.
For Erdner, who had lived in the same house for over 30 years, the tornado was a shock. Growing up in eastern Pennsylvania, she had never considered tornadoes or hurricanes as threats. Since that day, however, she has noticed an increase in tornado watches and warnings for her area, and she worries what this means for the future. “If this is some sort of effect from climate change, this is not going to get better, this is going to get worse,” she said.
Increased Tornado Activity in Pennsylvania
Erdner’s experience is becoming increasingly common in Pennsylvania and across the northeastern United States. According to the National Weather Service, 37 tornado warnings have been issued in Montgomery County since 1986, with 27 of them occurring after 2010. Tornado data for Pennsylvania as a whole shows a similar trend.
While tornadoes in the state were relatively rare in the mid-20th century, there has been a noticeable increase in activity since the 1980s. The most active years for tornadoes in Pennsylvania have all occurred after 1980, and 2023 has already seen 22 tornadoes in the state.
This rise in tornado frequency is not confined to Pennsylvania. A 2018 study co-authored by Victor Gensini, a tornado researcher at Northern Illinois University, found that tornado activity is shifting eastward, away from the traditional Tornado Alley in the Great Plains. States in the Northeast, Southeast, and Midwest are now seeing more tornadoes, while some areas in Texas, Oklahoma, and Colorado are seeing fewer. The data also suggests that tornadoes are becoming more concentrated, with more occurring on fewer days, and they are happening later in the year. Tornadoes, once primarily a spring and summer phenomenon, are now being recorded in the fall and winter months.
The Role of Climate Change
Erdner and many others are asking whether climate change is behind this shift in tornado activity. Scientists who study tornadoes say the answer is not simple. While some climate change-related factors, such as rising temperatures and increased moisture, can create more favorable conditions for tornado formation, other factors may not.
Harold Brooks, a senior scientist at the National Severe Storms Laboratory, compares climate change’s effects on tornadoes to a chain with many links. “We don’t even know exactly how many links there are on the chain, let alone what the chain is,” Brooks said.
Tornadoes are rare, and because they require specific atmospheric conditions to form, studying their long-term behavior is challenging. Tornado records in the United States only go back to the 1950s, and the data is often inconsistent. Tornado intensity is based on after-the-fact damage assessments, and changes in technology and population have affected the way tornadoes are documented. Thirty years ago, a weak tornado in a rural area might have gone unnoticed, but today, with smartphones and storm chasers, even the smallest tornadoes are captured on video and uploaded to the internet within minutes.
Despite these challenges, scientists agree that tornadoes are occurring more frequently in areas outside of Tornado Alley, including the Northeast. Gensini hopes that future research will make it possible to connect tornado activity directly to climate change through advanced modeling techniques. However, for now, the link between tornadoes and climate change remains uncertain.
Implications for Pennsylvania and Beyond
While the overall number of tornadoes in the Northeast remains small compared to states like Oklahoma and Kansas, the implications of an increase in tornadic activity in more densely populated areas are significant. A small rise in tornadoes in Pennsylvania, for example, could result in much greater damage and loss of life compared to rural areas of the Great Plains. Urban areas in the Northeast have higher population densities, and many homes and buildings are not built to withstand tornadoes.
Pennsylvania’s Emergency Management Agency (PEMA) has ranked tornadoes as a “medium risk” for the state, placing them alongside other hazards like droughts and wildfires. In 2023, the agency determined that more than 4 million Pennsylvanians live in areas vulnerable to tornadoes, and the total value of buildings exposed to tornado risks exceeds $1 trillion. Randy Padfield, PEMA’s director, emphasized the importance of public awareness, urging residents to pay attention to weather alerts and be prepared to take action if a tornado threatens their area.
A tornado watch means that conditions are favorable for a tornado to form, while a warning means that one has been sighted or detected on radar. Experts recommend that people take warnings seriously and move to a safe location, such as a basement or storm shelter.
For those unaccustomed to tornado warnings, the risk of ignoring them or becoming desensitized is real. “If you’re in sunshine and your phone is buzzing telling you to go to the basement and you didn’t even perceive a threat, I guarantee you, if you’re human, you will respond differently the next time,” Markowski warned.
Looking to the Future
For residents like Erdner, the increase in tornado activity is both alarming and confusing. Her neighborhood in Upper Dublin Township is still recovering from the 2021 tornado, and Erdner herself is more vigilant about severe weather alerts. “I pay a lot more attention to the weather now,” she said, “and I reach out to my neighbors when there’s a tornado watch, just to make sure everyone’s aware.”
While tornadoes remain relatively rare in Pennsylvania, the growing number of warnings and the shifting patterns of extreme weather have raised questions about how communities can prepare for the future. As climate change continues to alter weather patterns around the world, the need for better disaster preparedness and more resilient infrastructure becomes increasingly urgent. For now, the only certainty is that tornadoes can strike almost anywhere, and when they do, the results can be devastating.