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Weather Wise: Icy Roads

Weather Wise: Icy Roads
Posted at 5:18 PM, Oct 30, 2023

The only way you did not slide on the roads the last several days was likely because you did not drive. Last week's record-breaking snowstorm with record cold created icy roads that have lingered for days after the storm. It's not because snow plows were not working hard either. There was a unique set of circumstances that left a lot of people in the ditch.

Record snow and record cold came shortly after record warmth. Just days before the snow and cold arrived, temperatures were in the 70s and 80s. When the snow started to fly, the ground and road surface temperatures were still well above freezing, even as the air temperature dropped through the 20s and into the 10s. The snow almost immediately started to stick, but melting of that snow happened from underneath. the warmer ground slowly melted the snow, while cold air temperatures froze the melting snow into a sheet of ice. More melting occurred as the snow piled up. snow is an efficient insulator, and a deep snowpack on the surface slowed the cooling of the ground. Without the snow, the ground would have cooled off faster.

So a warm ground melted the snow, and kept melting it even until after the final flakes fell. This sequence created the icy and sometimes cobblestone surface on the roads that have been treacherous for days.

Warmer temperatures will melt some of this ice over the next few days, and the next snowstorm will not have as warm of a ground.