Thunderstorms dumped 5 inches of snow in two hours from approximately 6:30 PM to 8:30 PM per personal measurements. The National Weather Service Forecast Office in Duluth, MN measured 6 inches in two hours also during the early half of the evening. Personally observed lightning and thunder 6 times during the two hour period. The lightning was a particularly deep blue color. A lot of snow pellets mixed with the snow, making for a particularly dense snowpack. Some of the larger pellets were hard almost like hail as they bounced off the roofs of cars. Snow so intense that even a snowplow stopped at the side of the road, followed by several other vehicles that stopped behind it.
Snow accumulated 6 to 10 inches with 9.5 inches at the National Weather Service Forecast Office and 7 inches at a personal location.
The following radar image mosaics from the National Centers for Environmental Information show the intensity of the convection that produced the thundersnow.
6 PM CST January 1, 2005
7 PM CST January 1, 2005
8 PM CST January 1, 2005
9 PM CST January 1, 2005