Analysis of the Galvez-Davison Index for Convective Forecasts Over Africa Using the GALWEM
Technical Report,01 Apr 2018,21 Mar 2019
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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Thunderstorm forecasting over Africa has presented significant difficulty. The Galvez-Davison Index GDI was developed for the Americas and provides a more accurate convective forecasting index than the conventional indices for thunderstorm forecasting. Previous research using the GDI via the Global Forecasting System GFS model data over Africa showed promising results for areal coverage Donndelinger 2018, especially during the spring through fall months. This study will look to test the GDI via the Global Air Land Weather Exploitation Model GALWEM to determine if the GALWEM GDI forecast is able to more accurately forecast the location and areal coverage, as well as resolve airmass thunderstorms, when compared to the GALWEM K Index KI and GFS GDI forecast. Results from this study show the GDI and KI have similar location error at the 95 percent confidence level across the monthly, Zulu time, convective regime, and regional studies. GDI consistently outperforms the KI in terms of areal convection coverage in every study analyzed at the 95 percent confidence level. The GDI proves to perform best when convection is primarily airmass-based, while the KI performs best when convection is primarily from Mesoscale Convective Systems MCSs. Furthermore, Kelvin waves and outgoing longwave radiation OLR show promise as additional convective forecast tools for Africa.