During the first three weeks of December, the temperature averaged a frigid 11 degrees below normal, including one night below zero. Then the weather pattern switched: In the past week, temperatures have averaged 13 degrees above normal, during which time the low temperature has not fallen below freezing. Over the United States, the upper flow has been predominantly west-to-east with a powerful jet stream driving huge moisture-laden storms into the West Coast. Any remaining moisture and energy with these winter storms is dissipated over the Rockies, resulting in rather tame systems here with little rain or temperature contrast with frontal passage, now on a fast two- to three-day cycle.
Halfway around the globe, an upper low has settled over Europe, resulting in a steady diet of storm systems originating just east of Greenland. Wednesday’s storm brought central Europe to a standstill with significant snow, arctic cold and strong winds.
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
