Prepare for excitement: In this issue, we switch gears and take a look at a chart never seen before during the run of this puzzle feature. But it's one that is essential to forecasters. It's the upper air chart. In this issue, we'll explain what the upper level chart is and what it means. All you need to do is sketch the contour lines. By the end of this exercise, you'll be an up-and-coming expert in reading these charts
TIM VASQUEZ is a former Air Force forecaster and author of Digital Atmosphere, a weather forecasting software program. He lives near Norman, Oklahoma, where he keeps busy as a weather consultant and software developer.