How many inches of rain is equal to ten inches of snow?
The data is available if you know where to look. At most airports the NWS takes such data and lists it in their climate reports. Click on the map here for your region: http://nws.noaa.gov click on the local climate link on the left, and then the CF6 product for a location. There is also data from cooperative observers and some hobbyists & meteorologists – though that requires some searching. As some others have stated, the snow:water ratio can vary – though none yet mentioned the great extent it can do so. Wet snows are sometimes 6:1, lake-effect snows 50:1 or more (though their snow amounts are often exaggerated and the ratio typically quite a bit less). There was one lake-effect snow of 2 feet just downwind from Lake Michigan when the air was calm – flakes gently piled up on top of another, and then a strong wind came and basically blew it all away! I’ve taken quite detailed snow data here for the past 8 years:
