It looks like a widespread measureable snowfall will occur over much of the west half of the U.P. later tonight into Tuesday. Accumulations will range from a dusting at lower elevations to as much as four inches or so in the highlands of the west from Twin Lakes in Houghton County to the high country of Ontonagon and Gogebic Counties and then around the Huron Mountains of north-central Marquette Counties (Image 1 above). The amounts expected will pale in comparison to what happened on the west end 26 years ago.
Just the right combination of wind, cold and moisture brought the Gogebic Range a heavy snowfall on October 21, 1987. A daily-record 16 inches of snow fell in Ironwood, which is also a 24-hour record snowfall for the month of October. The heavy snow was a product of lake enhancement. A cold trough of upper air low pressure dug into the western Great Lakes (Image 2). This trough induced a surface low just east of the U.P. turning the winds to a favorable northerly direction at Ironwood (Image 3). Farther east, much lighter snows fell at the National Weather Service (NWS) site near Negaunee. A two-day total of 3.6 inches was observed on October 21-22, 1987. Then another clipper brought nearly 3 inches of snow over the next two days.
October 1987 was a cold, wet month. Rain and melted snow totaled 4.31 inches at the NWS, over an inch above average. At the same time, the average temperature was 5.3 degrees below normal.A cold, unsettled period is due for Upper Michigan for at least the next several days. A major upper-air trough has settled into the Upper Great Lakes (Image 4). This is a stable pattern and should hang on for much of the week. That means cold weather with some component of wind off Lake Superior. This will lead to shower development, which will mean frequent periods of rain and snow showers, especially in west to northwest-wind belts of Lake Superior.