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      Coldest So Early: Dec 11, 1977

      Expansive high pressure (lightest shading) combined with deep snow cover and clear skies led to record cold on December 11, 1977.

      Historic cold was experienced in Upper Michigan on December 11, 1977. This record-setter was preceded by big snows, especially those areas affected by lake-effect. Nearly 50 inches of snow fell from the 7th to the 9th at the National Weather Service site (NWS) near Negaunee. The thick blanket of snow provided ideal conditions for bitter cold as arctic high pressure built across the Midwest the night of December 10, 1977 (Image 1 above).

      By early morning on the 11th, Ironwood recorded 26 below--the coldest temperature for so early in the season. Iron Mountain residents shivered under their earliest sub-20-below zero morning at -21, while Herman crashed at 28 below and Kenton at 29 below zero. Underneath the center of high pressure just north of Lake Superior, the village of Armstrong, Ontario recorded 36 below zero.

      The cold broke afterwards. From December 13-21, the temperature in Marquette average over 10 degrees above normal. Then, just in time for Christmas, arctic air settled back in. The month ended 1.5 degrees below average. The winter as a whole came in just a little below average. However, much of the country was well below average during the winter of 1977-78 (Image 2).

      So far this month, the mean temperature at the NWS is running way below average. While the coldest air will retreat some, the overall pattern argues for well below average temperatures to continue.