The winter of 2009–2010 was destined to be one of the snowiest in the northeast United States since climate records began, and the snow events continued well into the month of February. So what does a snowstorm look like on the weather charts? In this issue we take a look at one such example.
This weather map depicts an early evening weather situation in February. 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.