In the last issue's Weatherwise (July/August 2013), we presented a challenging streamline puzzle, and not only was it an extra challenge, but the map was for India! In this issue, we'll take the difficulty down a few notches and return to more familiar surroundings. The isobars will be easy to draw, and the fronts should be a little more obvious. In the solution to this puzzle, we'll review this classic American summertime weather pattern and go over the basics.
This weather map depicts conditions in July during the early evening. Draw isobars every four millibars (996, 1000, 1004 mb, etc.) using the plot model example at the lower right as a guide. As the plot model indicates, the actual millibar value for plotted pressure (xxx) is 10xx.x mb when the number shown is below 500, and 9xx.x when it is more than 500. For instance, 027 represents 1002.7 mb and 892 represents 989.2 mb. Therefore, when one station reports 074 and a nearby one shows 086, the 1008 mb isobar will be found halfway between the stations. Then try to find the locations of fronts, highs, and lows.
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.