Sunday, 22 January 2012
A C-Band, Dual-Polarimetric Radar Analysis of a Tornadic Mesoscale Convective System: The 25 May 2011 Northern Illinois and Indiana Tornado Event
Hall E (New Orleans Convention Center )
During the morning hours of 25 May 2011, at least six tornadoes struck a narrow corridor of Northeast Illinois and Northwest Indiana. Two tornadoes were rated EF0, three EF1, and one EF2. These tornadoes occurred in conjunction with a mesoscale convective system (MCS) that traveled northeast across the region during the early to mid-morning hours, between 1200 UTC and 1500 UTC. The tornadoes occurred at least 65 km away from the nearest NEXRAD WSR-88D radar site. The confirmed tornadoes from this event occurred without severe thunderstorm or tornado warnings likely due to the fact that, (1) the squall-line was oriented parallel to the radar beam, (2) minimal real-time spotter reports, (3) embedded circulations were shallow, and (4) the tornado producing storms did not exhibit classic radar signatures at the nearest NEXRAD locations. The tornadoes occurred anywhere from approximately 50-75 km from the C-band dual-polarimetric radar located on the campus of Valparaiso University in Valparaiso, IN. Each PPI volume scan consisted of 14 elevations that took approximately 6.5 minutes to complete.
In this presentation, we examine the data gathered from the C-band, dual-polarimetric radar at Valparaiso University. We review the data in hopes of revealing methods that could have better detected the tornadoes produced during this event.