Highway frost was a major issue over Iowa on Tuesday morning. The featured chart presents the combination of RWIS air, dew point, and pavement temperatures for US Highway 30 near Jefferson along with the reported road condition by the Iowa State Patrol. The clear issue shown in the chart is having the road temperature below the dew point, which causes deposition of water vapor onto a frozen surface. Once the road temperature raises above the dew point, the frost was gone and the road reported as dry.

Voting:
Good = 14
Bad = 4
Abstain = 3

Tags:   frost   rwis