Parts of the Great Lakes saw a dramatic drop in surface water temperature late this past weekend into the early part of this week.
Much of this happened Sunday evening into Monday and part of Tuesday due to the passage of a cold front which produced some strong to severe thunderstorms over Lower Michigan and also turned the wind out of the north/northwest by Sunday evening. With lake temperatures already running a bit cool this summer (remember the lakes were completely iced over in early March) it didn't take much to stir up deeper/cooler water from mid-lake and push it closer to the eastern shoreline of Lake Michigan dropping temperatures along the beaches.
The most dramatic drop occurred near Ludington where the water temperature just offshore was a reasonable 64F Sunday evening before dropping all the way down to 39.2F in a little over 12 hours by Monday morning. That was a drop of 25 degrees or a little over 2 degrees every hour Sunday night! The temperature remained there for about 24 hours before rebounding back to 46.9F Wednesday morning.
Other locations also saw water temperatures drop Sunday night but not nearly as drastic as near Ludington. Just offshore of downstate Holland, the water temperature in the same timeframe went from 63F all the way down to 42F. At Michigan City, Indiana on the southeast end of Lake Michigan the temperature there went from a mild 79F back to 66F Sunday into Monday.
There were minor drops elsewhere, but not as drastic. The buoy in Little Traverse Bay near Petoskey dropped only 2 degrees from 66F to 64F. A very minor fluctuation. Out further in the lake, the mid-lake buoy halfway between the Manitou Islands, Michigan and Washington Island, Wisconsin also saw a drop in water temperature from 56F to 50.5F. The mid-lake buoy in Southern Lake Michigan's temperature drop was a little more pronounced going from 67F down to 59F and currently sits at 60.1F.
There was also a drop in water temperature on Lake Huron although it was more noticeable offshore. The buoy 32 miles northeast of Alpena dropped 6 degrees from 61.5F down to 55.5F.
One place that did not see a temperature change at all was out in the middle of Eastern Lake Superior where that buoy is holding rock steady and chilly at 38.1F.
These temperatures should slowly come back up as winds will turn more westerly with time and air temperatures by the weekend climb back well into the 70's.