A Numerical SImulation of the Goshen Tornado Observed During Vortex 2: An Orogenic Convective System

Friday, 19 December 2014: 2:40 PM
Gregory J Tripoli1, Scott T Trevorrow1 and Marcus Büker2, (1)University of Wisconsin Madison, Madison, WI, United States, (2)Western Illinois University, Macomb, IL, United States
A numerical simulation of the Goshen 2009 tornado observed during Vortex 2 is presented. The simulation is initialized from the North American Regional Reanalysis data set on the scale of the North American continent. The observed Goshen County tornadic supercell evolves in the simulation from the regional slope flow embedded an a favorable synoptic environment. A supercell and tornado were produced by the simulation in the approximate location and precise time that observations were made of the event by the Vortex 2 team. This was withoiut additional assimilation of high resolution observations beyond the standard data contributing to the 1500 UTC 35 km NARR analysis 7 hours prior to the observed tornado. The simulation can be and is compared directly to Vortex 2 Doppler observations. The process of orogenic storm organization driven by the interaction of topography and the large scale environment is discussed. It is hypothesized that the unusually high predictability of the timing and location as well as the system structure and attendant weather including tornado activity was the result of a highly predictable diurnal slope flow environment that constrained and so reduced the uncertainty of the simulation outcome.