VORTEX2: Mobile Upsonde Measurements and Studies of Lower Tropospheric Processes

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Supercells (long-lived rotating thunderstorms) have great impact on society, accounting for the vast majority of significant tornadoes as well as other severe weather. Recent climatologies and process studies have revealed the apparent importance of supercell outflow temperatures, as well as lower tropospheric vertical wind shear and lapse rates, to tornadogenesis. However, there are still causal links missing from the chain of physical processes that lead to supercellular tornadoes. This lack of knowledge is important because, without it, the ability to forecast and produce timely warnings for tornadoes (and to avoid false alarms for non-tornadic storms) is unlikely to improve. The goal of this research is to address this gap in the knowledge base through mobile upsonde measurements during the forthcoming Verification of the Origins of Rotation Experiment 2 (VORTEX 2), and through hypothesis-driven research incorporating both VORTEX 2 observations and idealized numerical simulations. The specific aims of the research are a) to understand the role of cold pool (outflow) dynamics in supercells and tornadogenesis; and, b) to understand storm-environmental interactions in mature supercells in terms of the near-storm lower tropospheric lapse rates. Intellectual Merit. The research will advance understanding of storm-scale processes in tornadic vs. non-tornadic supercells. Outcomes will include the delivery of: an important thermodynamic dataset for all VORTEX 2 Principal Investigators (PIs); results from tests of several hypotheses that have the potential to improve tornado forecasts and warnings. The research and measurements are expected to be significant, because together they will provide insight into key lower tropospheric thermodynamic processes in storms. Broader Impacts: Students will gain hands-on experience in storm observing and measurements. The PI will offer a course designed to prepare students for the field phase of VORTEX 2 and to provide a holistic sense of the mechanics of research projects. Finally, the PI will incorporate data and results into his routine courses and into his ongoing outreach effort that targets high school students. In addition to the routine venues of conferences and peer-reviewed journal articles, the PI frequently interacts with operational forecasters in the southeastern United States