2011 Chicago-Mackinac Race: A Meteorological Summary

Published August 2011

Mark A. Thornton

A Long Tradition
The Chicago Yacht Club sponsored the first sailboat race to Mackinac Island, Michigan, in 1898, earning it the distinction as the oldest freshwater race in the world. Over the next twenty-three years, the race was held sporadically and the course altered due to a variety of circumstances, including a hiatus prompted by World War I. But since 1921, the Chicago-Mackinac race, and its current course, has been an annual tradition.

Expanding from its humble origins, participation has grown from five yachts in 1898 to 355 in its 103rd running in 2011. The race's long tradition, combined with the challenges of the course, has brought it world-wide attention with many international sailors among the 3,500 participants. A race with such a long tradition develops a very loyal following. The Island Goat Sailing Society was formed in 1959 by 10 sailors who had participated in at least 25 Chicago-Macs. Devotion to the race has swelled the membership in this elite group to nearly 300 members who have spent countless hours competing.

The starting line for the nearly 300 nautical mile course is located near the mouth of the Chicago River. The shortest, but not necessarily the fastest, course takes the competitors northeast across Lake Michigan to the Michigan shore, past the Fox Islands and Beaver Island and under the majestic Mackinac Bridge to the finish line near Mackinac Island, Michigan. The size and speed of the boats vary considerably, but most competitors complete the journey in 30 to 70 hours. The monohull record, set in 2002 by Roy Disney aboard Pyewacket, was 23 hours, 30 minutes.

A 300-mile race is an obvious test of sailing skills and endurance. Weather conditions in the Great Lakes during the summer can be volatile, and many Chicago-Mac participants have experienced challenging conditions over the years. While a typical regatta can be delayed or cancelled in response to a threatening weather pattern, it is not feasible to abandon a long-distance race once it is underway. Observing the weather and managing the boat and crew in threatening conditions is simply part of the challenge. A historical summary of the race published by the Chicago Yacht Club sums up the race as follows; "Stripped down to its essence, the Mackinac event, like all sailboat racing, is still primarily a test of strength, endurance, strategy, willpower and a little sailor's luck thrown in for good measure. And let's not forget the dearest friend (and most menacing foe) of all sailors -- the wind."

Prior to 2011, not a single weather-related fatality had occurred in the race's 103 year history. This extraordinary safety record ended when the participants encountered a strong storm system crossing the upper portion of Lake Michigan late on Sunday, July 17th. This paper provides a meteorological analysis of the initial development of the storms during the 2011 Chicago Mackinac race, their transition into an organized system, and their transit across the lake.


Note: In order to coordinate the narrative to events in Michigan and a variety of imagery, all times are presented in Eastern Daylight Saving Time (EDT) and Greenwich Mean Time (GMT). GMT will appear in parenthesis after Eastern Daylight Saving Time and will be followed by a 'Z'.