Genesis and Structure of the 2013 El Reno, Oklahoma Tornado: Comparison of Cloud Model Simulations and Ground-Truth Observations

On 31 May, 2013, a record-breaking 4.2-km wide tornado with radar-measured winds ≥135 ms^-1struck central Oklahoma near El Reno causing eight fatalities. Elsewhere at this conference, Houser et al. use synchronous videographic and Rapid-Scan X-Band Polarimetric (RaXPol) data to demonstrate that the El Reno tornado formation occurred at the surface beneath a preexisting supercell mesocyclone prior to (by ~90 sec) the development of a vertically continuous tornado vortex signature. In this poster, we compare the observed tornadogenesis and subsequent character of the ensuing circulations to comparable data fields derived from ultra-high resolution cloud model simulations of the El Reno Storm performed on the Blue Waters supercomputer.

The RaXPol radar collected an unprecedented dataset during tornadogenesis, acquiring data as low as ~10 m above ground level. Crowd-sourced collections of video footage from storm chasers provided the basis for a comprehensive visual depiction of the supercell and tornado evolution from crowd-sourced still and video photography (The El Reno Survey Project; Seimon et al. 2015). Through spatio-temporal linking utilizing lightning flash frequency characteristics and Google Maps geolocations, all videos were synchronized to within one video frame (0.03 sec) , creating a comprehensive visual database and enabling a detailed analysis of the storm from a variety of viewing angles and distances ( see http://el-reno-survey.net/ted/).

A 30-m resolution CM1 simulation was initialized with the conditions adjacent to the supercell that produced the record-width tornado using model-based soundings, retrieved from a 3-km WRF model simulation initialized in turn off the 31 May 2013 12 UTC GFS analysis. The CM1 simulation contains a strong, long-lived supercell producing a broad tornado-strength circulation; however the simulation does not exhibit the high-intensity sub-vortex features within the broader circulation in the actual event. Several additional simulations within the 31 May 2013 environment, utilizing a variety of model parameters, will be described and compared to observations. Using multimedia animations of both observed and simulated circulations played out side-by-side in real-time, this presentation will demonstrate how multi-perspective imagery paired with radar can be used synergistically to validate cloud model simulations and attempt to reconstruct a tornadic supercell at high spatial and temporal resolution.