Dear Tom,
After the Sept. 12-14 deluge across the Chicago area, I'm wondering how much snow
would have fallen had it been mid January instead. I'm guessing since the ground would
be frozen, it would greatly exceed the eight to ten inches of rain that hit most areas.
Rick, Crown Point, Ind.
Dear Rick,
"Greatly exceed" is quite an understatement. A typical snow-to-water ratio in big
snowstorms around here is 12-1 (12 inches of snow will melt down to one inch of
water). The ratio varies greatly because it is strongly affected by air temperature, wind
speed and snowflake size during the storm. The state of the ground in the winter,
frozen or unfrozen, isn't too important. The 12-1 ratio works well for temperatures in
the upper 20s with moderate wind with little drifting and a mix of snowflake sizes. That
said, 8 to 10 inches of rain would yield 96 to 120 inches of snow.
