Supercells (long-lived rotating thunderstorms) have great impact on our society, accounting for the vast majority of tornadoes and very large hail, and also often producing intense local rainfall and damaging non-tornadic winds. Recent climatologies and process studies have revealed that cold pool (outflow) properties, lower tropospheric vertical wind shear, and lower tropospheric stability are fundamental to processes such as supercell maintenance and tornadogenesis. However, true "cause and effect" remains elusive because there are still a number of unknown physical links. This lack of knowledge is important because, without it, the ability to forecast and produce timely warnings (and avoid false alarms) for supercellular hazards is unlikely to improve. This research seeks to address gaps in the knowledge base by continuing our hypothesis-driven research on fundamental supercell processes. This study includes both analyses of recently-collected data from the Verification of the Origins of Rotation Experiment 2 (VORTEX2), as well as numerical simulations that are motivated by and compared to those measurements.
The goal of this application is to analyze the lower tropospheric outflow processes and storm-environment feedbacks in tornadic and non-tornadic supercells. To accomplish the goal of this application, the project will pursue three specific objectives: 1) explain the downdraft processes that produce surface vorticity beneath supercells; 2) establish the comparative importance of low-level vertical wind shear vs. low-level stability in the maintenance or demise of supercells; and, 3) identify the near-storm environmental modifications produced by supercells.
Intellectual Merit This study directly addresses three of the VORTEX2 scientific foci: tornadogenesis, relationships between supercell storms and their environments, and storm-scale numerical weather prediction. The research is innovative because it exploits the cutting edge VORTEX2 dataset to attack gaps in the knowledge base, and because it addresses a number of novel hypotheses for production of surface vorticity in supercells. The outcomes of this effort will include advanced understanding of low-level processes in supercells, including dynamics associated with tornadogenesis, storm maintenance, and storm-environment interactions. The research is expected to be significant, because it will provide additional insight into severe storms that threaten citizens' lives and property.
Broader impacts Given the considerable initial outlay of public funds for the VORTEX2 campaign, continued support for analysis of VORTEX2 data is a well-leveraged investment. In the face of 2011's historic number of tornado fatalities, advances in supercell and tornado forecasting and warning would be in the public interest.
This project will support training and mentoring for graduate students as well as a postdoc. The PI also continues to incorporate data and results from VORTEX2 into his routine courses. The high profile of the experiment and unprecedented datasets make the results extremely appealing to students. The PI also has an ongoing commitment to involving underrepresented groups in his research and field work. The PI agrees to restriction-free share VORTEX2 mobile soundings data with the community, and is committed to helping the community fully exploit those data. In addition to the routine venues of conferences and journal articles, the PI will interact with operational forecasters from the National Weather Service, teach operational short courses, and present public research talks on VORTEX2.
