25 January 2013

"Pond-effect" snow ?

Most people who live in cold climates are aware of the phenomenon of "lake effect snow."  Even so, it's sometimes startling to realize the  magnitude of the effect.  The image above, from Paul Douglas' On Weather blog, shows a recent dump of 32 inches of snow on Oswego, New York - in one day.

What I learned yesterday while reading up on this at Dr. Jeff Masters' Wunderblog, is that a long fetch over open water is not mandatory.  His photo illustrating the Oswego event -

- shows, in addition to the 32" snowfall at the far right, areas of enhanced snowfall downwind from power plant cooling ponds (lower left corner).
Note the thin streaks of snow to the southwest of Lake Michigan in north central Illinois. According the the National Weather Service in Chicago, these bands of snow were lake-effect induced, but not from Lake Michigan--the snow was due to cold air flowing over warm waters in power plant cooling ponds. Image credit: NASA.
And here's a close-up image from the Chicago NWS:

You learn something every day.

1 comment:

  1. So... is that why Madison got a lot of snow before Christmas? And I live by a little lake. Incredibly interesting to those of us who are directly effected.


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