P79  Investigating the Role of Storm Mergers and Rapid Storm     Intensification Mechanisms in the 22 May 2011 Joplin, MO   Tornadic Storm

Van Leer, Kevin W., Brian F. Jewett, Robert B. Wilhelmson, University of Illinois

With a goal of capturing the mechanisms involved in the sensitive tornadogenesis process, this study utilizes the WRF model to simulate the 22 May 2011 Joplin tornadic event.  On this day, an EF-5 tornado was produced in a low vertical shear environment, atypical for violent tornadoes of this magnitude.  This places an emphasis on the investigation of alternate sources for low-level shear enhancement, such as storm-mergers and boundary interactions.  Simulations utilize NAM or RUC native grid initializations and boundary conditions with multiple physics and nest placement combinations. Current model runs at grid spacings of approximately 100 meters reveal sensitive storm-scale processes, not only to the environment, but also to model configurations.  Vertical soundings retrieved from vital times and locations in the real-data simulations provide input for idealized runs and tests of resulting storm structure and behavior due to varying shear and thermodynamic profiles.  Further analysis of both types of simulations will focus on identification of specific mechanisms for low-level shear enhancement in this case and others with similar storm environments.