Though global warming and Arctic Ocean melt are continuing to make headlines and stir heated debate, at press time the northern hemisphere was once again heading into winter. It's usually the United States that attracts attention with its Canadian outbreaks, Alberta clippers, Great Plains blizzards, and nor'easters, but beginning in late 2009, Europe began experiencing a succession of unusually severe winters. The first half of the 2011-2012 winter season brought a respite, but in this issue we'll take a look at a return to frigid conditions in February 2012.
This weather map depicts conditions in early February in the predawn hours. 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 lowss.
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.