In over 100 years of weather records, Ironwood was never as cold so early as on October 4, 1980. The temperature fell to 19 degrees, while the next morning brought another record low of 17. Both Iron Mountain and the Houghton County Airport reported record lows of 21 degrees.
The cold was spawned by a deep trough of upper-air low pressure that dug into the Great Lakes drawing in cold air from the north (Image 1 above). The big upper low brought a little snow each day between Oct 2-4 at the National Weather Service (NWS) near Negaunee, with 1.1 inches accumulating on October 3. Up until October 2002, October 1980 was the coldest tenth month recorded at the site. The mean temperature for the month came in 6 degrees below the long-term average. Snowfall for the month totaled 11.9 inches.
The system affecting us this weekend will not be very cold, but it will be wet. And now it appears the low may take its sweet time leaving. The latest model run of the GFS shows the upper-air low over Iowa Sunday morning (Image 2). Originally, the model had the low already lifting north through the Lake Superior region at the same time. Now instead of lifting north, it is forecast to meander eastward, winding up over the Lower Peninsula on Tuesday (Image 3). The European Model, which was the first to show the low slowing down, also concurs with the GFS. If this scenario unfolds, clouds and a chance of at least some rain will hold on into Tuesday.