Using short range ensemble forecasts, climate anomalies, and high resolution model guidance to determine the potential for a tornado outbreak across the southern plains on 10 May 2010

Forecast products from the Short Range Ensemble Forecast (SREF) and the Global Ensemble Forecast System (GEFS) are used with forecast output from the 3 km High Resolution Rapid Refresh (HRRR) and the 4 km NCEP NMM WRF models to identify the severe weather potential associated with a tornado outbreak that occurred across the Southern Plains on 10 May 2010. This study will demonstrate that SREF probability forecasts and deterministic high resolution model solutions shouldn't be considered as mutually exclusive approaches to forecasting. Rather, the strengths of each approach can lead to a better forecast when assessing the potential for severe weather impacts. This case also demonstrates the value of using forecast departures from climatology to highlight areas conducive to widespread severe weather.

This study demonstrates a forecast strategy that utilizes 1) SREF probability forecasts to assess the likelihood, storm type potential, and predictability of the event; 2) SREF/GEFS forecast departures from climatology to evaluate the climatological context of the event; and 3) high resolution model output to determine the details of moisture, instability, lifting/forcing mechanisms, and convective mode (e.g., cellular, linear, etc.). This study also highlights a “forecast funnel” approach that utilizes ensemble data to evaluate event potentials in the extended and mid ranges of a forecast (days 2-7), and progressively higher resolution model output to assess the important details of the short term forecast (day 1).

A well-predicted tornado outbreak spread across the southern plains during the afternoon and evening hours of 10 May 2010. The volatile pre-storm environment prompted the SPC to issue a high risk for severe weather for central Oklahoma and southeast Kansas preceding the event. Preliminary reports indicate 42 tornadoes in Oklahoma and Kansas and more than 164 reports of severe weather over the Southern Plains. High impact events included destructive tornadoes across parts of Oklahoma and Kansas, 4-5 inch hail over parts of Oklahoma, and wind gusts of 75-100 mph across parts of Kansas.