Residents of the Gogebic Range shivered under the coldest March temperature ever recorded on this date in 1984. It hit 34 below at Ironwood. Farther east near Negaunee, the National Weather Service (NWS) site only dipped to 16 below; still a record low for the date. The record cold was produced by a dramatic pattern shift that occurred just as a record-warm February ended. The second month set three high temperature records during the month at Ironwood, including a 60-degree high temperature on February 23rd. Record temperatures at Ironwood are significant because they go back to the turn of the 20th century. At the NWS site, where records have only been kept for a little over 50 years, it was one of the warmest second months in the record (exceeded only in 1998) with a mean temperature 11 degrees above average.
The pattern flip brought intensely cold air in for the first third of March. In late February, an upper-air ridge in the central U.S. promoted record warmth over Upper Michigan (Image 1 above). By the beginning of March, a deep trough over eastern Canada sent arctic air into the U.P (Image 2). The seven-day period from March 6-12 averaged 21.3 degrees below the long-term standard. Three times during this period the low exceeded 20 below zero. Two times the high temperature only made 5 above.
The cold moderated a bit at mid-month and at the spring solstice a tremendous snowstorm occurred. Twenty-eight point two inches fell at the NWS on March 21-22, 1984. After the storm, a 40-inch covering of snow was measured. At month??s end, there was still a two-foot snow pack. The last of the snow cover disappeared on April 16, 1984.
This year, March has started cold. Through the first six days, the mean temperature sits at 13.8 degrees; 5.9 below the long-term average. Mild weather looks to set in for a few days. However, the overall pattern still argues for cold. It still appears that high-latitude blocking will hang on into mid-month at least (Image 3). This means the tendency for development of high pressure in Canada, which is a cold signal for us.