MNDOT and WISDOT Warn Of Slippery Roads And Black Ice During Extreme Cold
In the face of dangerous wind chills, drivers are being told to take extra care while driving due to the threat of black ice and "blow ice" making for slippery driving conditions. While we aren't seeing any new snow, windblown snow and the extreme cold are leading to slippery roads around the region.
Both the Minnesota and Wisconsin Departments of Transportation have cautioned drivers that slippery conditions are possible through this cold snap, asking drivers to slow down and drive extra with extra care. There have also been many reminders to make sure you have a winter survival kit in your car in the event of a breakdown or other incident.
When it gets as cold as it is with wind to blow snow around, you've probably seen that glaze that develops on roads - especially in open areas on highways. MNDOT calls it "blow ice", which is the result of that drifting snow sticking to road surfaces, melting and re-freezing. When it's this cold, how could snow melt? Friction, the relative warmth of tires on the roadway, and pressure of tires pressing the snow into the roadway all play roles in this process.
Also of note, the Duluth-bound lanes of the Blatnik Bridge have been closed due to weather conditions. Bridges and overpasses are particularly dangerous places for black ice, where cold air can pass both over and under a surface to contribute to ice formation.