How To Use The Synoptic Composite von Jack Sillin / 10/25/2017 / No Comments In this video, forecaster Jack Sillin explains how to use our newly added Synoptic Composite to forecast the behavior of storms. About the author Jack Sillin Jack Sillin is an Atmospheric Science student (Cornell '22) and weather forecaster who regularly writes for weather.us and upportland.com. Follow me on twitter @JackSillin. Comment Cancel reply Save my name, email, and website in this browser for the next time I comment.