This last stretch of cold weather during late February into the first week of March caused ice concentration on Lake Michigan to rapidly increase. The Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor Michigan measures the ice concentration on the Great Lakes daily. On March 8th, the ice concentration on Lake Michigan was measured at 93.29%. This sets a new record ice cover on Lake Michigan. The previous record was 93.1% set in 1977. The period of record dates back to 1973.
The below graph shows the rapid increase in ice concentration since late February.
The below high resolution visible satellite animation begins on February 24th and includes several images of the past week, ending on March 8th. It shows considerable ice cover over the Lake during this first week of March.
Below are several images from the Grant Park and Bradford Beach areas over the past several days showing the extensive ice cover at the shore, however open water was visible farther away from the shore.
The below graphic prepared by GLERL estimates the ice thickness in centimeters on Lake Michigan. Most of the ice to the east of southeast Wisconsin ranged from 18 to 36 cm thick or about 7 to 14 inches.
The total ice cover on the Great Lakes from March 8th was estimated to be over 90% as depicted by the below graphic from GLERL. The record ice cover for the Great Lakes is 94.7% set in 1979. The lowest on record is 9.5% in 2002.
Warmer weather and stronger winds should cause the ice to erode this next week.
National Weather Service - Milwaukee/Sullivan