Patrick Skinner, Cooperative Institute for Mesoscale Meteorological Studies, The University of Oklahoma

Performance of the NSSL Experimental Warn-on-Forecast System in Varying Mesoscale Environments

Dustan Wheatley, Kent Knopfmeier, Louis Wicker, Corey Potvin, and Ryan Sobash


The National Oceanic and Atmospheric Administration’s Warn-on-Forecast project is tasked with producing probabilistic, short-term guidance for severe thunderstorm hazards in the United States. Working towards this goal, a WRF-based, ensemble, storm-scale data assimilation and prediction system has been developed and run for select cases during the springs of 2013 through 2016.

This system, known as the National Severe Storms Laboratory Experimental Warn-on-Forecast System for ensembles (NEWS-e), has regularly predicted high probabilities of strong low-level rotation in supercells approximately 30 minutes in advance of tornado reports. However, many of the case studies have focused on intense storms within highly favorable environments for tornado development. This study will compare past NEWS-e performance with cases occurring in marginal tornado environments, characterized by strong vertical wind shear and relatively weak conditional instability, occurring during the 2016 VORTEX-Southeast field campaign. Specific foci will include development of appropriate verification measures for storm-scale ensemble forecasts of low-level rotation and the impact of convective-scale data assimilation on the mesoscale environment.

File available here