Travel was very difficult early Tuesday morning for many Iowans due to a layer of ice that formed on roadways. The setup for this icing event was rather tricky as shown by the featured chart. The chart depicts Jefferson RWIS road pavement and air temperatures, solar radiation observations from the Jefferson KCCI-TV SchoolNet and DOT/DPS Road Condition Reports. The yellow bar represents the time period that a road segment near this road sensor's location was reported to be partially covered with ice. The temperature time series show the interesting combination of having air and dew point temperatures above freezing with road temperatures below freezing. This combination along with falling rain left to the rain freezing on the road surface. The rain also likely helped to wash off much of the pre-treatment done on Monday. The cold front then trucked through after 10 AM dropping the air temperature below freezing as well, but the clouds broke up during the afternoon hours and pavement temps warmed back above freezing even with falling air temps. Many locations further north did not have pavement temps warm back above freezing and icy conditions remain a problem there.

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Tags:   rwis   icing