Never mind the open spot that is still visible from my vantage point on Lake Monona, but the State Climatology Office reports that both Lake Mendota and Monona are now frozen.
Since the term frozen over or iced over can be somewhat subjective let us just all agree that winter is here, and the lakes are frozen.
On January 1st I posted about the first ice on Lake Monona, and a picture.
Lake Mendota’s freeze comes more than two weeks after Lake Monona’s, which froze on New Year’s Eve. Lake Wingra was reported frozen on Dec. 21.
For the 2011-12 winter, Monona and Wingra froze Jan. 3 and Dec. 11, respectively.
The State Climatology Office admits that determining the freeze date is not an exact science, but it has maintained a database of ice cover records dating to the mid-19th century for those three lakes.
To keep the records as consistent as possible, the office uses observational methods, passed down by oral tradition, for determining when the lakes are open or frozen.
Lakes Monona and Wingra have a general, somewhat subjective “50 percent covered” rule for determining the lake is iced over, with a few preferred vantage points for assessing ice cover.
Applying the same rule to Lake Mendota has been more of a challenge historically because of the lake’s shape and irregular shoreline.
Today, the Climatology Office uses a vantage point on the 13th floor of the Atmospheric and Spaces Sciences Building, 1225 W. Dayton St. For observers in the 1800s, there was no vantage point sufficient in height.
A secondary criteria was developed for that lake: whether one can row a boat between Picnic Point and Maple Bluff. It emerged from the era of pioneering University of Wisconsin limnologists E.A. Birge and Chancey Juday, who frequently used that method to transport a case of beer to friends in Maple Bluff.