5.4 Thermodynamic Environmental Conditions Leading to Tornadogenesis

Thursday, 11 January 2018: 11:15 AM
Room 19AB (ACC) (Austin, Texas)
Sean W. Freeman, Colorado State Univ., Fort Collins, CO; and S. C. van den Heever, B. H. Kahn, and P. M. Kalmus

Supercellular thunderstorms pose a significant threat to humankind by virtue of the severe weather they produce, including tornadoes, large hail, lightning, and heavy rainfall. While the environmental conditions leading to supercells are relatively well understood, discriminating environments leading to tornadic supercellular thunderstorms from environments that lead to nontornadic supercells is still a difficult forecasting problem. Satellite data could be useful in helping to discriminate between these environments by leveraging the higher spatial coverage of satellites compared to the traditional radiosonde network. However, the sensitivity of satellite observations of the environmental thermodynamic profile necessary to discriminate between environments of nontornadic and tornadic supercells has not been evaluated. The goal of this work is to understand and quantify the sensitivity of satellite thermodynamic soundings needed to distinguish between these environments. In order to achieve this goal, the Regional Atmospheric Modeling System (RAMS) has been used to perform a series of idealized supercell simulations with horizontally homogeneous initial conditions that are varied by simulation. These simulations were run at very fine grid spacing, thereby allowing for the resolution of a near-surface tornado-like vortex. The A-Train constellation was used to provide observations of the environments supporting tornadic and nontornadic supercells. The A-Train observations used in this work are discussed in more detail in the companion abstract, “Using satellite observations to assess environmental variability in proximity to supercells and their likelihood for tornadogenesis” by Kahn et al. The partitioned data from each set of thermodynamic observations were used to guide the manner in which the environmental thermodynamics were perturbed in the idealized simulations in order to represent tornadic and nontornadic supercell environments. The results from these simulations were then used to understand the thermodynamic sensitivity necessary to discriminate between tornadic and non-tornadic environments.
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