Interactive Mesoscale Analysis Utilized in Assisting Local Decision Makers: A Review of the 24 March 2005 Supercell

Severe weather associated with various convective modes affected the forecast area of Weather Forecast Office (WFO) Tulsa, Oklahoma the evening of March 24, 2005. Of interest was the evolution of an isolated supercell that tracked across southeastern Oklahoma and maintained identity through a cycle between dominate cyclonically and anti-cyclonically rotating updrafts. The supercell developed and maintained an anti-cyclonic updraft from its initiation through the mid point of its lifecycle, before transitioning to a cyclonically rotating dominant updraft during the latter stages of its lifecycle. KTUL and KSRX WSR-88D radars sampled this evolution, with both velocity and reflectivity signatures supporting a transition of the storm's dominant updraft. Interactive mesoscale analysis techniques employed real-time at WFO Tulsa revealed a negative storm relative helicity environment in advance of the storm. These values, calculated from an observed storm motion, transitioned through a sharp gradient and became positive along the storm's path. This suggested a potential for the cyclonically rotating updraft to become dominant, resulting in a change in storm structure. This potential was relayed to customers via locally issued mesoscale forecast discussions, with an emphasis toward storm spotter groups within the potentially affected counties. The evolution of the supercell, along with the corresponding mesoscale analysis graphics, will be shown. Additional discussion will focus on how this information was relayed to local users, particularly the effort to assist local officials in directing their storm spotter groups.