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Thundersnow
Wed Apr 14, 2004
Listen in RealAudio 
Thunderstorms typically show up when it's hot and sultry. Snow makes the scene only
when it's cold. But once in a while, you'll see this odd couple stepping out. Hi, I'm
Bryan Yeaton for The Weather Notebook.
The result is a rare phenomenon called "thundersnow," and some scientists are trying
to find out how rarely it occurs. The University of Missouri has teamed up with NOAA
and the National Center for Atmospheric Research for a five-year study to learn where
and why thundersnow develops. If you could survive a balloon ride into the heart of a
severe springtime storm, you might see thundersnow up there where it's well below
freezing. It's that contrast between warm, moist air below and cold air above that
produces instability and generates the electrical juice for lightning. In the winter, it's
harder to crank up that instability.
Missouri professor Patrick Market, who's leading the new study, has already found that
certain parts of the country are especially prone to this phenomenon. One strip from
Colorado to Wisconsin sits just to the left of a common track for wintertime storms. As
these cyclones lift northeast, they pull milder air from the Gulf of Mexico underneath
cold upper air. Another way to get instability is when bitterly cold air passes over an
unfrozen body of water. This happens over the Great Lakes and near the Great Salt
Lake.
Where thundersnow does develop, it can dump huge snowfalls in a short period.
Louisville, KY noticed a few lightning flashes as their city got buried by two feet of snow
back in 1994. You may have also noticed The Weather Channel's Jim Cantore caught
in a thundersnowstorm a few years ago.
The Weather Notebook is supported by grants from Subaru of America and the
National Science Foundation. If you'd like to report thundersnow, check out our Web
site: www.weathernotebook.org.
Today's Links
Research on Convective Snow
http://solberg.snr.missouri.edu/ROCS/particip.html
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