December 1, 2012

What Will Your Winter Be Like?

By Mary Kay Carson 

December heralds many holidays, family feasts, vacations, as well as the winter solstice. This year, on December 21 at 6:12 am EST our sun will max out its southern declination. Friday the 21st will be the year's shortest day. And while we'll add a few seconds of sunshine everyday following the solstice, the cold deepens. The thirteen weeks of winter will have begun.  
     So what will winter be like in your part of the country? Predicting winter temperatures and precipitation is the job of the National Oceanic and Atmospheric Association (NOAA). Every autumn, they combine data and crunch numbers to forecast snow and cold for the United States and present their best guess to the public. NOAA's 2012-2013 Winter Outlook calls for a wetter than average winter in the South and a drier season in the Northwest and upper Midwest. Both Florida and Hawaii are predicted to be cooler than average while much of the West has a warmer than normal forecast.
     A fun thing to do is to mark your March calendar with your region's predictions. Then you and your students can ask: How accurate was the Winter Outlook forecast in your region?

     While NOAA's seasonal forecast might call for a colder and wetter than average winter in a particular place, it does not predict snowfall amounts. Why not? Winter storms are notoriously tricky to predict. A change in just a few degrees in temperature within the column of air above the storm as it moves can make the difference between a cold rain, sleet event, or snowy pileup. Here's a fun activity from a book of mine, Weather Projects for Young Scientists. It explores the differences between two types of winter precipitation: sleet and snow. Here's hoping your winter is a good one! 

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