Lake Michigan UpwellingJuly 31st, 2014 at 12:48 am by Bill Steffen under Bill's Blog, News, Weather
Picture on the left from the Muskegon GLERL camera Wednesday afternoon (from NOAA Coastwatch). The high temperature on the beach at Muskegon was 60.1° at 7 pm. The fog was caused by condensation as higher dewpoint air came across the very cold water. The water temperature at Holland State Park Weds. morning was 41°. I had to ask twice “are you sure, 41°? The buoy west of Muskegon showed a water temp. of 43° (as I write this near midnight, the water temp. at the buoy was back to 47°) and the last I checked, the water intake temperature at S. Haven was 45°. The graph in the middle is the water temperature at the buoy west of Ludington. Wow! The water temperature dropped from 63.6° to at least 39° in less than 24 hours. The graph on the right is from the buoy west of Port Sheldon, showing a drop from the low 60s to the low 40s. This cold water came from well below the surface through a process called upwelling. We had a strong north wind behind a cold front and that pushed the surface water toward the middle of the lake, allowing much colder water from 100 feet below to rise to the surface. Here’s a diagram to show what happened. Here’s another example of upwelling from 2012. This is a more thorough discussion and has a list of some historical upwelling. Needless to say, this can be quite dangerous for anyone in water that cold. This is especially a concern for someone that may take a boat out and decide to just jump off the boat into the water. The mid-Lake Superior buoy showed a water temperature of 39.2° when I checked on Wednesday and the east Lake Superior buoy had a water temp. of 38.3°. Here’s a look at the water temperature of Lake Michigan this year compared to recent years. Lake Superior not only is considerably colder than even 2009, but it appears to be about 20°F colder than the end of July in 2012. Lake Huron is now also colder than 2009. Here’s a five-year comparison for Lake Ontario and Lake Erie.