WASHINGTON, DC (WOWO) When severe storms leave behind damaged homes, downed trees and debris, one of the National Weather Service’s first priorities is determining whether the destruction was caused by straight-line winds or a tornado. That process, known as a storm survey, combines damage ass essments, radar analysis, eyewitness accounts and modern technology to determine whether a tornado touched down and, if so, how strong it was. Mike Ryan, a senior meteorologist with the National Weather Service office in Indianapolis, said storm surveys resemble investigative work, with meteorologists piecing together multiple sources of evidence according to Fox 59. “I think storm surveys are almost like forensic meteorology,” Ryan said. “There are really three key pieces. There’s obviously the damage survey piece itself. How is the damage laid out? Are there signs of a path or twisting? How significant is the damage? Because that tells us something about the wind speeds.” Survey teams are typically deployed after severe weather when reports of significant damage are received. Their first task is determining whether the damage resulted from straight-line thunderstorm winds or rotating tornado winds. Investigators examine the pattern of destruction, looking for signs of rotation, converging debris and a continuous damage path that would indicate a tornado. If survey crews conclude a tornado occurred, they then determine its intensity using the Enhanced Fujita, or EF, Scale, which estimates wind speeds based on the type and severity of damage to buildings, trees and other structures. The EF Scale ranges from EF0, with estimated winds of 65 to 85 mph, to EF5, with estimated winds exceeding 200 mph. Ryan said damage alone is not the only factor considered. Meteorologists also review radar data collected during the storm. “What did the radar show us?” Ryan said. “Was there a tornado debris signature? Was there rotation that would support that idea?” Radar can reveal strong areas of rotation within thunderstorms and, in some cases, detect debris lofted into the air by a tornado, providing additional evidence that a tornado touched down. Meteorologists also rely heavily on eyewitness accounts from residents affected by the storm. “There’s a sensitive piece to it,” Ryan said. “These are people that have had their lives impacted. But we find that they usually do want to talk.” He said information about what people saw and experienced can help investigators better understand the timing, location and behavior of a storm. “What did they experience? What did they see? And that all helps to piece things together for us,” Ryan said. Technology has also become an increasingly valuable tool in storm surveys. Emergency management agencies frequently provide drone footage that allows meteorologists to examine damage in areas that are difficult or impossible to reach on foot. Ryan said drone imagery proved especially useful following the EF3 tornado that struck Owen and Monroe counties on June 17, where much of the damage occurred in heavily wooded terrain. “So usually when we coordinate with them, a lot of times they’ve sent the drone up already,” Ryan said. “With the Monroe-Owen County storm, that went through a lot of heavily forested areas that we wouldn’t be able to get to. So that drone footage was really helpful.” The National Weather Service also receives photos and videos from emergency responders, trained storm spotters, storm chasers and members of the public through email and social media, helping investigators verify tornado paths and document damage. Officials encourage anyone who experiences storm damage to report it to their local National Weather Service office. Damage reports, photographs and videos can provide valuable information that helps meteorologists confirm tornadoes, determine their strength and improve future severe weather warnings. By combining field surveys, radar data, eyewitness accounts and advanced technology, National Weather Service meteorologists are able to reconstruct storms after they pass, providing communities with accurate information about what occurred and helping improve the understanding of severe weather events. The post How the National Weather Service Determines Tornado Strength After a Storm appeared first on WOWO News/Talk 92.3 FM and 1190 AM. ...read more read less