FARGO — The number of vehicle crashes Wednesday and Thursday morning around North Dakota and western Minnesota was extraordinary due to relatively light snow. Roads were covered in a thick layer of ice Wednesday morning as warm weather in the weeks leading up to the storm had left ground temperatures well above 32 degrees. What then happened is called a flash freeze.

With the arrival of the snow, the temperature quickly fell into the 20°C. The snow melted on impact with the warm ground, and the thermodynamic process of melting the snow crystals into water carried a lot of heat away from the ground. The slush layer turned to ice, then wind and light snow all day Wednesday kept that ice polished. The ice remained until reduced winds Thursday allowed solar radiation to melt the road ice. Most of this winter’s storms will not occur under these circumstances.

John Wheeler is chief meteorologist for WDAY, a position he has held since May 1985. Wheeler grew up in the South, in Louisiana and Alabama, and cites his family’s move to the Midwest as being important in developing his fascination with weather and climate. Wheeler lived in Wisconsin and Iowa when he was a teenager. He attended Iowa State University and graduated with a bachelor’s degree in meteorology in 1984. Wheeler worked about a year at WOI-TV in central Iowa before moving to Fargo and WDAY.