84th AMS Annual Meeting

Sunday, 11 January 2004
Winter weather precipitation type forecasting
Room 608/609
Daniel J Pydynowski, North Carolina State University, Raleigh, NC
This project was undertaken to develop a new method to forecast precipitation type that enhances the utility of existing methods. Precipitation type surface observations were collected from Greensboro, NC (GSO) from 1998 to 2003. The surface observations, 1000-850mb thickness, and lapse rate were recorded and plotted onto the new diagram, or the “lapse rate nomogram.” The "lapse rate nomogram" combines the thermodynamic principles used in the “area method” forecasting technique and the empirical approach used by the “partial thickness” forecasting technique. Though current precipitation type forecasting methods are quite accurate, the goal of this research was to introduce lapse rates combined with 1000-850mb thicknesses into one single diagram called the "lapse rate nomogram." By using lapse rate, this technique will more accurately predict precipitation type. This new “lapse rate nomogram” could be especially useful along the coastline as well, where lapse rates are often high in winter weather situations. Though no one stand-alone diagram can ever forecast precipitation type flawlessly, this research provides yet another tool for the always difficult task of forecasting precipitation type.

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