CEDAR RAPIDS, Iowa (KCRG-TV9) -- The vast majority of the time, if the air temperature is above freezing, then icing won’t be an issue. There are times, however, that it’s not quite that simple. That was the case on Tuesday, especially in northern Iowa.
Several days of cold weather led to very cold pavement. Even as temperatures came up, the roads didn’t warm up as quickly, and that lag led to icing on roads. Thankfully, ice was not a problem on trees or power lines.
The graph below plots weather data from a roadway observation sensor near Decorah. The red line shows the air temperature, and the pink line shows the pavement temperature. The air temperature rose above 32 degrees around 4 a.m., but the pavement was still only around 27 degrees – about five degrees behind. It managed to hover near freezing from late morning into the afternoon, and only briefly got above 32 degrees around 2 p.m. By that time, the air temperature was beginning to drop, and the pavement temperature followed suit.
Not only do we forecast the weather, but we also try to predict the impacts that weather will have. There are a lot of factors that go into that second part, and how the pavement responds to the weather around it just one of them.