Newswise — Winter Storm Fern swept across a large swath of the southern and eastern United States, delivering not just a wide range of snow accumulation, but also snow types. Experts say one big reason for those differences comes from a meteorological phenomenon — that the same amount of total precipitation can deliver very different amounts of measurable snowfall, depending on the underlying conditions.

Barrett Gutter, a meteorologist at Virginia Tech who teaches classes in weather analysis, weather forecasting, and severe weather, explains that the snow-to-liquid ratio (SLR), or how much moisture is in a snowflake, can be impacted by a number of factors.

“Very dry snow, which often occurs in mountainous terrain and higher latitudes, can have SLR values closer to 20:1 (20″ of snow = 1″ of liquid), while very wet snow, which often occurs in the southeast, can have SLR values closer to 6:1,” he says.

This explains why snow totals in the Rocky Mountains are often much higher than along the east coast ranges. But elevation isn’t the only determining factor.

“Lower temperatures throughout the atmosphere will lead to drier and fluffier snow (higher SLR) since there tends to be less moisture available, while higher temperatures (closer to freezing) will lead to wetter and denser snow.”

Other factors that impact snow-to-liquid ratios include the height in which snowflakes form, moisture content, and wind speed.

This led to record snowfall totals in places like Toronto, which received nearly two feet of accumulation, while the mid-Atlantic got less total snow, but several inches of sleet, which settled into hard-packed ice.

About Gutter
Barrett Gutter is a collegiate assistant professor of meteorology. Gutter teaches a wide variety of courses, including Weather Analysis, Weather Forecasting, Severe Weather, and Radar and Satellite Meteorology. He also leads a two-week storm chase field course during the summer.

Interview
To schedule an interview with Barrett Gutter, contact Noah Frank at nafrank@vt.edu or 805-453-2556.