An Algorithm to Automatically Generate Convective SIGMETs over the Contiguous United States

Forecasters at the Aviation Weather Center are responsible for producing Convective SIGMETs (CSIGs), which are polygons, lines, and points that indicate areas of dangerous convection. On meteorologically-active days, an intense demand is placed on the forecaster, as he/she must constantly monitor several environmental parameters across the entire National Air Space and manually draw CSIGs as the weather is evolving. Making the process more difficult is the plethora of different convective regimes that may require CSIGs. Herein, we present a new tool designed to streamline the process of generating CSIGs. This tool, the CSIG recommender, uses a combination of composite reflectivity, echo top, and lightning density to identify areas that pose a threat to the safety of flight and produces polygons, lines, and points every 10 minutes with attributes that can be used to populate the CSIG formatted text. The algorithm has been evaluated for three years and shows good agreement with manually-generated CSIGs. Artificial intelligence that has been included in the CSIG recommender to handle situations such as scattered areas of isolated thunderstorms or geometrically-complex shapes will also be discussed as will adaptations to the algorithm to provide CSIG-like polygons for specific flight layers. Lastly, we discuss methods to apply the algorithm to ensemble weather prediction output in order to generate a 0-2 h probability of a CSIG.