While summer and winter often bring stagnant weather patterns, spring is a time of rapid change as intense solar heating clashes with deep polar air masses and cold ocean temperatures. This contrast adds fuel to the atmospheric engine, bringing an assortment of fast-moving systems and changeable weather to the temperate latitudes. In this issue, we’ll look at a powerful springtime weather system that stretched across the Rocky Mountain region.
This weather map is for an event during a late afternoon in May. Draw isobars every 4 millibars (1008, 1004, 1000, 996, 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 millibars when it is more than 500. For example, 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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The solution appears on page 66.