In 2007 the National Weather Service began officially issuing short-term warnings based on polygons rather than counties. The use of Geographic Information Systems to work with these warnings is quite beneficial. Warnings can now be verified using GIS and new performance metrics can be computed from within GIS. In addition, for several years GIS shapefiles of these warnings have been produced and can be utilized to analyze long-term trends with warnings, including the effectiveness of this new Storm-Based Warning methodology.

This presentation will describe how this warning information is converted into GIS formats and how these data are analyzed both in near-term as well as over periods of time. In addition, new statistical methods will be discussed, including results based on recent warnings issued.