Dear Tom,
What is the conversion for inches of rain into inches of snow?
Bill Argast
Dear Bill,
It is widely believed that an inch of rain will yield about 10 inches of snow, but this is only true when temperatures during the snow are hovering around the freezing mark. When temperatures are a bit warmer, say in the middle 30s, the same inch of rain may only produce 6 to 7 inches of wet, slushy snow. In contrast, when the snow falls with readings in the teens or 20s that same inch of rain could produce as much as 20 to 25 inches of snow.
In general, the lower the temperature during the snowfall, the higher the snow-to-water ratio. At subzero readings, it would take about 50 inches of melted snow to produce an inch of water. Locally, some of the highest snow-to-water ratios in the neighborhood of 30-40:1 occur during lake-effect snow events.
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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.
