When converting snowfall amounts to rain or water equivalents, the temperature plays a role.
A snow-to-liquid ratio is used to convert liquid precipitation to snow. The snow-to-liquid ratio depends on temperature. The colder the temperature, the higher the snow-to-liquid ratio.
For example, 10 inches of snow at 34 to 28 degrees would equal 1 inch of water. At 19 to 15 degrees, 20 inches of snow would equal 1 inch of water.
Want to do some conversions yourself? Here’s a link to the Snowfall/Meltwater Table from the National Weather Service.
Although the NWS lists snowfall amounts separately in its climate data, it also converts the snowfall to water when calculating total precipitation. To do the conversion, meteorologists take core samples from snow on the ground at 1 p.m. each day and melt it to determine the amount of water in the snow that day. Those water amounts are then added to rainfall amounts to determine total precipitation.
Date posted: January 12, 2011
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