great-lakes-water-temps-final.jpg

This map shows current surface water temperatures on the Great Lakes. Lake Superior has a large area of water with temperatures in the 40s.

(Great Lakes Environmental Research Laboratory)

Lakes Superior and Lake Michigan are currently six degrees colder than last year. If the water continues to remain colder than normal, it could have an impact on Michigan's winter in several ways.

The average water temperature on Lake Superior and Lake Michigan is currently colder than both last year and the long-term average.

Currently Lake Superior has an average surface water temperature of 47.6 degrees. Last year on this date Lake Superior was at 53.7 degrees. The long-term average water temperature on Lake Superior for October 11 is 51.1 degrees.

So Lake Superior is 6.1 degrees colder than this time last year, and 3.5 degrees colder than normal.

Lake Michigan has an average surface water temperature of 56.0 degrees, while last year at this time it was 62.1 degrees. The long-term average water temperature on Lake Michigan for October 11 is 58.4 degrees.

Lake Michigan is also 6.1 degrees colder than this time last year, and 2.4 degrees colder than average.

Lake Huron is 5 degrees colder than last year, and only 1.5 degrees colder than normal.

How can this impact Michigan's winter?

The Great Lakes surrounding Michigan, especially Lake Superior and Lake Michigan, influence our winter temperatures and snowfall.

A warmer Lake Superior and Lake Michigan can really have a modifying effect on bitter cold temperatures. For example, in an early season cold outbreak, Green Bay, WI may have a temperature of 20 degrees. Traverse City, on our side of Lake Michigan, may hold in the mid 30s for temperatures. I usually figure there is a 10 to 20 degree warming effect from Lake Michigan, and also Lake Superior.

But if the lake temperatures continue at this colder pace, cold air will have an easier time moving into Michigan.

So the first impact of cold water could be earlier cold temperatures in November and December.

If the lakes continue through winter colder than normal, freezing over of the lakes would happen earlier.

As for snow, part of Michigan's snow is obviously lake effect snow. Lake effect snow is heaviest when the lake waters are warm, and the air above is very cold. The bigger the difference in lake to air temperature, the more intense the snow can fall. Colder lake waters would mean lake effect snow could be not as intense. That is not to say we won't still have what some would call heavy snow. It means the 24 to 36 inch lake effect snows in one to two days would be harder to achieve.

The colder water, as mentioned above, could freeze earlier. This would end the lake effect snow season earlier.

So, to summarize, if the lakes stay colder than normal, our air could get colder earlier in winter, but lake effect may not be as heavy.

But November is important

If we went into an extended stretch of warmer than normal temperatures for the rest of October and November, the lakes wouldn't cool as fast as normal. So this whole situation above could actually be reversed by the time we get to December 1. There currently is some indication that the next two to three weeks will average slightly warmer than normal.

We'll just keep watching all these factors, and I'll try to make a guess at what this winter brings. I think the first week in November will be a good time for that guess. Yes, I am using the word "guess".

If you have any questions or comments, post them below.

MLive Chief Meteorologist Mark Torregrossa has been forecasting Michigan weather for more than 20 years. He's been chief meteorologist at three television news stations in Michigan, and he's an avid gardener and hunter. Email him at mtorregr@mlive.com and find him on Facebook at facebook.com/mark.torregrossa and Twitter @weathermanmark