"THERE IS THE POTENTIAL FOR SIGNIFICANT ACCUMULATION OF SNOW THAT MAY IMPACT TRAVEL AND COMMERCE."
The Watch can be upgraded to a Warning (meaning that a winter storm is imminent), downgraded to an Advisory (snow will be likely but should not be too serious), or the Watch can be canceled if severe weather is no longer expected for the area.
The exact location of the heaviest snow is not yet known, but the high terrain of the Bayfield Peninsula may receive up to 6 inches, with more possible in the Penokee Range of Ashland and Iron counties. Lower elevations and areas near Lake Superior will see less.
Wind may also be an issue, starting to increase New Year's Eve from the northwest, reaching up to 20 mph by Sunday afternoon. Gusts of 30 mph are possible with even higher winds over the Apostle Islands, eastern in the Upper Peninsula, and the open waters of the Lake.
Even without heavy snow, the wind may cause blowing and drifting across roadways. Local road conditions and reported incidents are always available on the Wisconsin DOT's website (linked here), make sure "Incidents" and "Road Conditions" are checked.