Investigating Thunderstorm Characteristics and Hazards Disposition: A Case Study of Correlations Between DCLMA Total Lightning Flash Information and NEXRAD Signatures in the Baltimore-Washington Urban Corridor

On June 29, 2012, a derecho, a widespread, long-lived, straight-line wind storm associated with a fast-moving complex of severe thunderstorms known as a mesoscale convective system (MCS), progressed over 700 miles across the United States from the Midwest exiting off the eastern seaboard. This derecho began as a lone thunderstorm cell in central Iowa continuing into Illinois; where with the aid of a very moist warm air mass it developed into an MCS. During this 700 mile trek across the US, the storm continued to pick-up forward speed and convective instability allowing the event to continue cohesively despite crossing the Appalachian mountains. Eastward of the Appalachians the mid-Atlantic was under an oppressive temperature and moisture regime which invigorated the storm with Convective Available Potential Energy (CAPE) as high as 5,500 J/kg, considered extreme instability prime for severe weather. A significant late night “light show” of mainly inter cloud lightning as well as an intense “wall of wind” as the leading edge of the storm arrived locally in the Baltimore-Washington metropolitan area.

National Weather Service (NWS) Storm Prediction Center (SPC) storm reports indicate the most severe winds of the storm were in the Baltimore-Washington area with measurements as high as 87 mph (140 km/h), leading to widespread damages including multi-day power outages, downed trees, damaged homes, and loss of life.

In order to better understand the intricacies and differences between severe thunderstorms of varied scales and dispositions, such as strong wind, torrential rain, and/or severe electrification vs moderate rain, and/or little to no electrification; a multi-event case study is investigating the correlation between the 3D total lightning flash information from the National Aeronautical and Space Administration (NASA) Washington DC Lightning Mapping Array (DCLMA) and reflectivity and velocity signatures from the NWS Sterling, VA Next Generation Radar (NEXRAD). Current cases under investigation include the aforementioned June 2012 Derecho as well as the Old Ellicott City catastrophic flash flooding event from July 30, 2016. Further cases are being added to this investigation to explore the hazard outcomes from T-storm dynamical environment differences.