Observations of an Unusual Nonsupercellular Tornado

An unusual nonsupercellular tornado occurred in Huntsville, Alabama, on 30 January 2013. This tornado produced EF0 damage along an approximately 5-km path. The 30 January convective event consisted of numerous bands of convective cells, none of which were well-organized into a traditional quasi-linear convective system (QLCS). The circulation associated with the Huntsville tornado formed via an interaction between a fine-line (~15 dBZ maximum reflectivity factor) associated with a cell embedded within one band of convection and the rapid growth of a new convective cell with a separate band of convection located approximately 10-15 km to the west. As this fine line interacted with this convective cell, the fine-line formed a curl, with a circulation noted at the southern tip. This circulation was associated with the observed EF0 damage in southwest Huntsville. The circulation developed directly over the Advanced Radar for Operational and Meteorological Research (ARMOR), with first damage noted approximately 3.85 km to the east, while both the convective band from which the fine-line originated and the cell from the western convective band that was associated with the tornado both passed directed over the Mobile Integrated Profiling System (MIPS) at the University of Alabama in Huntsville (UAH), affording vertical profiling of the structures and characteristics of cells within each convective band. Additionally, both bands passed over two 1-minute resolution automatic surface observing stations (ASOSs), located at Huntsville (KHSV) and Decatur, Alabama (KDCU) and spaced approximately 15 km apart along a west-east axis, as well as a 5-second resolution surface observation platform at UAH. In this presentation, we analyze the development of this tornado and the structure of the convective bands by integrating ARMOR, MIPS, and surface observational platforms. We compare characteristics of the convection within the bands to environmental characteristics estimated by model analysis soundings to characterize potential wave properties associated with the convection. Implications on tornado climatology and the need for additional investigation of external influences on severe convective storms are discussed.