Update on the turbulence nowcast product GTGN for NextGen IOC

Recent turbulence accidents have re-confirmed the need for better turbulence forecast and nowcast products for aviation. Presently being developed at NCAR for the NextGen IOC, under sponsorship from the FAA's Aviation Weather Research Program (AWRP), is the Graphical Turbulence Guidance Nowcast, or GTGN, product. GTGN aims to provide a gridded picture of the current turbulent conditions over the Continental US by seamlessly combining the best turbulence observations and forecasts available at the time of update. Building upon GTG, the current turbulence forecast product that updates hourly based upon model output, GTGN will update on a more rapid 15 minute cycle. In addition to GTG, GTGN will incorporate the Convectively-Induced Turbulence diagnostic product DCIT, as well as various observational data including in situ EDR reports from commercial aircraft, pilot reports of turbulence, TAMDAR EDR measurements, and the NEXRAD Turbulence Detection Algorithm (NTDA). Together, GTG and GTGN will act as the single authoritative source with regard to turbulence forecasting and nowcasting. Where GTG allows for strategic planning, GTGN, by combining all these data into one cohesive turbulence nowcast, will provide a streamlined way for pilots, en-route controllers, airline dispatchers, and aviation meteorologists to obtain information they need to make tactical decisions. In this paper we will describe the overall methodology behind the product, including different techniques being considered to assimilate the various data. Cases studies and a preliminary statistical analysis will also be presented.