Dear Tom,
My friend says it has to be 32(degrees) or lower to snow, but I disagree. How warm can it be and still snow?
Paul W. Washington,
Appleton, Wis.
Dear Paul,
Your friend is wrong on this one. Temperatures must be 32(degrees) or lower in the cloud layer where the snowflakes form, but because the flakes can fall about 1,000 feet without melting in an above-freezing environment, they can reach the ground with surface readings well above the freezing mark. Snow has fallen in Chicago with readings as high as the lower and middle 40s, though it quickly melted upon impact.
One of the warmest recorded snows occurred during the 1970s in Jacksonville, Fla., where flakes fell with a temperature of 53(degrees). In addition to very cold air just above the warm surface, dew points were in the teens, and added cooling from evaporation into the dry air helped to keep the flakes from melting.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
Write to: ASK TOM WHY, 2501 Bradley Pl., Chicago, IL 60618 or asktomwhy@wgntv.com (Mail volume precludes personal response.)
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
