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January-February 2011

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Forecast Center

During the winter season, three key storm tracks affect the United States: a southeastward storm track from Canada, an eastward track from the Pacific, and a northeastward track from the Gulf of Mexico. In this issue we take a look at the Pacific track, comprising the single most important weathermaker west of the Mississippi River. In spite of their meteorological and economic importance, these systems can be quite difficult to follow because of their interaction with the high, rugged terrain of the western United States. Try your hand at finding such a system in this puzzle, and on the solution page we'll present some expert tips for a better understanding of how they work.

This weather map depicts a morning situation in November. 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.

For further information, 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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