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Joseph T. Schaefer, James P. Travers, Thomas A. Heffner, A. Dale Eubanks, Armando L. Garza, Lans P. Rothfusz, Walter A. Rogers, Sylvia K. Graff, James T. Skeen, Kenneth Haydu, and M. Lee Harrisons

The National Weather Service sponsored a workshop on aviation weather on 10–12 December 1991, in Kansas City, Missouri. The theme of the workshop was the improvement of service to the aviation community through the application of technology and advanced forecast techniques. The 150-plus people who attended the workshop included a cross section of operational forecasters, pilots, research meteorologists, and representatives of the aviation industry. The workshop included sessions on user requirements, operational procedures, and the impacts of new technology on the forecast products. There were also four “hands-on” laboratory sessions where participants produced various types of aviation weather products. The interaction between the user community and working-level forecasters made the workshop a unique event.

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David J. Stensrud, Ming Xue, Louis J. Wicker, Kevin E. Kelleher, Michael P. Foster, Joseph T. Schaefer, Russell S. Schneider, Stanley G. Benjamin, Stephen S. Weygandt, John T. Ferree, and Jason P. Tuell

The National Oceanic and Atmospheric Administration's (NOAA's) National Weather Service (NWS) issues warnings for severe thunderstorms, tornadoes, and flash floods because these phenomena are a threat to life and property. These warnings are presently based upon either visual confirmation of the phenomena or the observational detection of proxy signatures that are largely based upon radar observations. Convective-scale weather warnings are unique in the NWS, having little reliance on direct numerical forecast guidance. Because increasing severe thunderstorm, tornado, and flash-flood warning lead times are a key NOAA strategic mission goal designed to reduce the loss of life, injury, and economic costs of these high-impact weather phenomena, a new warning paradigm is needed in which numerical model forecasts play a larger role in convective-scale warnings. This new paradigm shifts the warning process from warn on detection to warn on forecast, and it has the potential to dramatically increase warning lead times.

A warn-on-forecast system is envisioned as a probabilistic convective-scale ensemble analysis and forecast system that assimilates in-storm observations into a high-resolution convection-resolving model ensemble. The building blocks needed for such a system are presently available, and initial research results clearly illustrate the value of radar observations to the production of accurate analyses of convective weather systems and improved forecasts. Although a number of scientific and cultural challenges still need to be overcome, the potential benefits are significant. A probabilistic convective-scale warn-on-forecast system is a vision worth pursuing.

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