In winter and early spring, much of North America is rocked by powerful frontal systems. Interestingly, these are some of the strongest fronts on the planet because of the large areal extent of the landmass into polar latitudes, along with the presence of large north-south mountain ranges that help to channel air masses north and southward. In this puzzle, we'll take a look at one such example of a strong frontal system. This weather map depicts conditions in late afternoon in early January. 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.
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