Forecasting Extreme Wet Bulb Globe Temperature (WBGT) with a Mesoscale Numerical Weather Prediction System

Heat is a hazard to personnel at many military test facilities. One traditional measure of that hazard is the wet bulb globe temperature (WBGT), an empirical index calculated from air temperature, humidity, wind, and solar radiation. Observations of WBGT at military facilities generally are taken at a limited number of locations and can be manually intensive and quite sensitive to the condition of the instrumentation. Because WBGT is an important factor in management of heat exposure, it would be useful if WBGT were more commonly included among the standard analyzed and predicted variables in operational weather forecasts at military facilities. Spurred by this motivation, the authors will present initial results from a set of trial algorithms for approximating maximum WBGT from the output of the Four-Dimensional Weather (4DWX) System, which is used by meteorologists of the US Army Test and Evaluation Command (ATEC). Results will include validation of each algorithm against WBGT observations from selected stations at several ATEC test ranges.