Get Ready for Winter: Learn How to Measure Ice

Winter weather comes in many forms, but freezing rain can often be the most impactful. Unlike snow or sleet, freezing rain falls as a liquid, and then freezes on contact with cold surfaces, creating a hazardous layer of ice. 

The National Weather Service forecasts and measures what’s known as radial ice, the thickness of ice accumulation on a cylindrical object, like tree branches or power lines.

Why? Because it’s the direct link to real-world damage. Just a quarter-inch of radial ice is enough to snap branches and bring down power lines, even less if it's windy!

Want to measure it yourself? 

1. Locate an ice-covered object that is out in the open, such as a small tree branch.
2. Position yourself to see both the thickest and thinnest ice portions around the object.
3. Using a ruler, measure the thickest part of the ice, from the edge of the object to the edge of the ice.
4. Measure the thinnest part of the ice using the same method.
5. Average the two measurements to calculate the total ice accumulation.

Measurements as small as 0.01” are recorded and archived for use in the historical record, in post-storm analyses, and for verification.

 

The next time you get freezing rain, if it’s safe to do so, go measure how much radial ice you received and report it to your local Weather Forecast Office! Find your local office by visiting https://www.weather.gov/, then type in your location in the top left corner.