Description and evaluation of the second generation Graphical Turbulence Guidance forecasting system

The first generation Graphical Turbulence Guidance (GTG1) became "operational" in March 2003 for use by meteorologists and airline dispatchers as an aid to forecasting areas of upper level (>FL200) clear-air turbulence (CAT) over the continental U.S. GTG uses a combination of individual turbulence diagnostics derived from NCEP's Rapid Update Cycle (RUC) forecasts weighted by comparisons to turbulence pilot reports. This technique of combining diagnostics has been shown to provide superior performance to the use of individual diagnostics alone in producing automated turbulence forecasts. Since the original GTG release, development of the second generation GTG, GTG2, has been ongoing under sponsorship of the FAA Aviation Weather Research Program (AWRP). GTG2 includes several improvements over GTG1, including the use of new turbulence diagnostic algorithms, better thresholding of the individual diagnostics, and extension of forecasts to mid-levels (FL100-FL200). GTG2 is scheduled to become "operational" in early FY06. A brief description of the GTG2 product as well as preliminary statistical evaluations of GTG2 probabilities of detection performance are provided.