How to Measure Snow
Measuring snow can be fun and it is relatively easy to get a good measurement if you follow just a few simple guidelines. One of the biggest mistakes made by people who measure snow is that they may measure drifted snowfall resulting in higher measurements. Below are some quick and easy guidelines on how to measure snowfall: http://www.crh.noaa.gov/iwx/program_areas/snow_spotters/SnowMeasurement.pdf .
BEFORE THE FIRST SNOW
Place your snowboard outside. A snowboard can be any lightly colored board that is about 2 feet by 2 feet. A piece of plywood painted white works very well. Choose a location that is away from trees, buildings, and shadows. Try to avoid areas that are known to be prone to drifting. Mark the location of the snowboard with a stake so you can find it after a fresh snowfall.
Snowfall is measured to the nearest tenth of an inch. Measure the greatest amount of snowfall that has accumulated on your snowboard since the last observation. You can measure on a wooden deck or ground if a snowboard is not available. Snowfall should not be measured more than 4 times in 24 hours. You can measure the hourly snowfall rate, but do not clean off your board each hour. Only clean off the board when you take one of the four daily measurements. Once the snow ends, add up the measurements from each time the snowboard was cleaned to reach a storm total.
– Snow falls and accumulates on the snowboard, but then melts. In this case, the snowfall is the greatest depth of snow observed on the board before it begins to melt. If this occurs several times, measure the snowfall after each snow shower and add each measurement for the total snowfall.
– Snow falls and melts continuously on the board. In this case, if the snow never reaches a depth of a tenth of an inch, then a trace of snowfall is recorded.
– Snow has blown or drifted onto the snowboard. In this case, take several measurements from around the yard where the snow has not drifted, being careful only to measure new snow. Take an average of the various measurements to arrive at a total.
– Sleet counts towards total snowfall, freezing rain accumulation does not.
MEASURING SNOW DEPTH
The depth of snow on the ground includes both new snow and old snow which was in place. Measure the total snow depth at several locations in your yard which have not drifted or blown. Take an average of these measurements to arrive at the snow depth.
Sometimes old snow can be very hard and crusty underneath the new snow. Be sure that the ruler gets all the way down to the underlying ground. Snow depth is measured to the nearest inch.
MEASURING SNOW WITH A MEASURING STICK
Find a location where the snow appears to be near its average depth. Avoid drifts or valleys. Look for a flat, somewhat open area away from buildings and trees. Some trees in the distance may be helpful in making a wind break, preventing drifting, and thus providing for a more even distribution of the snow. Measure the depth with the snow measuring stick (aka “the common household ruler”) at several locations and use an average. Traditionally ten measurements are made and the average value is the snow depth. When snow has fallen between observation times and has been melting, measure its greatest depth on the ground while it is snowing. Typically, you will measure once a day at the same time, however you can measure twice a day, three times a day, or four times a day, but never more than four times. If all snow melted as it fell, you can report a trace for the snowfall.