Steam from one or more plants on the east side of Norfolk, Nebraska, was helping to generate snow that blew far to the south around midday Monday, the National Weather Service said.
The conditions Monday were just right for such snow generation, said Brian Barjenbruch, a meteorologist at the weather service’s Valley office.
On a normal day, Barjenbruch said, the steam goes up into the air and evaporates. But Monday, he said, the steam interacted with ice already in the clouds, allowing more snow to form.
Monday “offered a perfect combination of cold temperatures in a very specific temperature range for snow development,” Barjenbruch said. “We’ve already got moisture in the air. We’ve already got ice crystals in the clouds. Those three are the main ingredients for producing snow. The addition of more moisture (from the steam) is helping it snow,” he said.
National Weather Service radar showed light snow blowing south from Norfolk to the Seward and Lincoln areas, he said. The intermittent light snow in the Omaha area, he said, was unrelated to the steam-enhanced snow.
Barjenbruch compared the phenomenon to lake-effect snow, in which cold, dry air passes over warmer water. He said he had heard of a similar case occurring recently in Pittsburgh, where a large amount of steam generated by a plant resulted in snow blowing downwind.