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March-April 2018

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Forecast Center

Although we often think of winter as being marked by snow, freezing rain, and sleet, quite often it's the cold that makes the news. In this puzzle, we'll explore the weather patterns associated with a cold air outbreak and talk about high pressure, polar air masses, and their life cycles.

This weather map depicts conditions in January during the evening hours. Draw isobars every four millibars (996, 1000, 1004 millibars, 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 millibars when the number shown is below 500, and 9xx.x when it is more than 500. For instance, 027 represents 1002.7 millibars and 892 represents 989.2 millibars. Therefore, when one station reports 074 and a nearby one shows 086, the 1008 millibar isobar will be found halfway between the stations. Then try to find the locations of fronts, highs, and lows.

For a detailed, printable version of this map, along with helpful hints and advice, visit


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

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