Fishing on the Great Lakes is highly dependent upon the weather.  An intimate understanding of the weather that happened days ago, the current conditions, and the impending forecast will help to improve our ability to catch fish.  Knowledge of the surface conditions whether it is "pancake flat", rippled, or filled with rolling waves will alter your presentation.  Knowledge of the surface and sub-surface temperatures allow us to understand and target the "desired fish conditions" and appreciate the thermocline.  Finally, knowledge of the surface and sub-surface currents will be needed to ensure that our baits have appropriate action.  

One phenomenal resource that I have used to gain an understanding of the currents in the Great Lakes is a book by the late Professor Emeritus F.R.S. Clifford H. Mortimer, called "Lake Michigan in Motion".  It can be found online and has helped more than one fisherman to understand these "Great Lakes".

Take a look at some of these "Weather Resources" and familiarize yourself with the content.  They are all used in one way or another on any given day.  The great John A. Bergfeld, MD says that "Preparation and attention to detail is always the Key to Success!!"  This is ever so true while fishing.