How to Gauge Snowfall

Gauging snow requires effort and patience.

Unlike measuring rain, gauging snowfall presents challenges. Snow mixes with rain or sleet, blows into drifts or melts, and all these factors can inhibit an accurate measurement. For these reasons, the National Weather Service recommends two low-tech ways to gauge snowfall: measuring snow with a yardstick and collecting it in a rain gauge.

Things You'll Need

• Snow board, a 24" x 16" piece of plywood painted white
• Yardstick
• Rain gauge

Instructions

Snow Board Method

1. Place your snow board on open, flat ground with limited human activity. Mark the board with a flag or reflector so that you can find it after the snowfall.

2. Slide the yardstick into the snow until it hits the board to measure the snowfall immediately after it stops. Record the snowfall to the nearest tenth of an inch.

3. Sweep the snow board clean and place on top of the snow. This prepares it for the next snowfall measurement.

Rain Gauge Method

1. Place the gauge in an open area free from trees, eaves and other obstacles.

2. Collect the rain gauge immediately after the snow stops falling. Before bringing the gauge inside, tap on the top of it with a flyswatter or other flat object. Clean away all the snow that falls outside the gauge.

3. Dip the snow sample in hot water carefully to melt it. Don't allow any of the sample to spill or any of the hot water to get inside the rain gauge.

4. Measure the snowmelt in the rain gauge and consider the type of snow. The water-to-snow ratio in the U.S. averages 10:1, meaning 1 inch of melted snow equals 10 inches of snow. This ratio varies based on the type of snow. Wet snow may have a 5:1 ratio, while dry, blowing snow has a water-to-snow ratio of 20:1 or higher.

Tips & Warnings

• Using two snow boards will allow you to measure the snow depth, the total amount of snow on the ground, as well as the current snowfall.

• Measure from a snow board if windy conditions affect the amount of snow collected in a rain gauge.

References

• Community Collaborative Rain, Hail & Snow Network: Guide to Measuring Snow
• NOAA's National Weather Service; Cooperative Observer Program; Snow Measurement Guidelines
• CBS Minnesota; Good Question: How Do They Measure Snow?; Jason DeRusha; December 2009
• The Weather Prediction; Snow to Liquid Equivalent; Jeffy Haby

Resources

• University Corporation for Atmospheric Research Magazine; How Deep the Snow?; Bob Henson; May 2011