Some of you may have been in the water at the area's Lake Michigan Beaches last week when water temperatures were all in the 70s. If you have seen or felt the beach water temperatures this past weekend, you will know that they are much colder, as water temperatures are now generally in the 50s. This drastic change in water temperature is a result of the strong Northeast winds from the wet system that affected the area last Thursday and Friday. This process is called "upwelling".
Below is a set of images from Michigan State University Remote Sensing and GIS Research and Outreach Services. The image on the left is a map of water temperatures from Wednesday, August 8th. The image on the right is a map of water temperatures from Saturday, August 11th. Click on the image to zoom in.
Notice how the cold water temperatures are only located within a few miles of the Michigan shore.
The cold shoreline water compared to the remainder of Lake Michigan is very evident on satellite imagery that senses temperature. The image below was taken from Saturday evening around 11 pm EDT. The lighter colors on the eastern side of Lake Michigan indicate colder temperatures than the remainder of the lake.
Below are graphs of the water temperature near the surface of the water. The graphs are water temperatures that are taken from buoys offshore of Ludington and Holland. Notice the steep decline of water temperatures. It is during that period in which the upwelling was occurring.
Ludington Water Temperature Graph (Courtesy of Michigan Tech Great Lakes Research Center)
Holland Water Temperature Graph (Courtesy of Michigan Tech Great Lakes Research Center)
Below is an image of how the water at the shore got so cold, so fast. "This is the process of upwelling".
The water temperatures on the shoreline will recover as westerly winds develop and push the warmer waters back into the area. Any sunny days will also help to warm the shallow shoreline a bit. You can see water temperatures that are taken daily at the State Parks and other locations along the shore at: http://forecast.weather.gov/product.php?site=grr&product=omr&issuedby=grr
You can look at satellite derived water temperatures each day courtesy of Michigan State University Remote Sensing at: http://www.coastwatch.msu.edu/twomichigans.html