Updraft Category Archive: Lake Superior

Lake water temps hit 80 degrees

Posted at 5:00 AM on July 24, 2010 by Paul Huttner
Filed under: Lake Superior, Lakes

Lake water temps near seasonal highs:

A check of water temperatures near the Weather Lab in Lake Minnetonka this week shows a surface water temperature of 82 degrees. This is at or slightly above the peak average temperature for southern Minnesota lakes, which usually takes place from late July into mid- August.

July sunset on Lake Minnetonka. Water temperature 82 degrees.
(photo by Paul Huttner)

Even Lake Superior is showing unusually warm temps this summer with lake water temps near 70 degrees at the mouth of North Shore rivers like the Knife River.

Changes in wind direction over Lake Superior cause upwelling to bring frigid water to the surface with little warning in some areas. It is interesting to watch water temps fluctuate wildly in summer. Surface temperatures may be near 70 one day, and plunge into the 50s or even 30s in some areas with little warning. Keep that in mind if you are thinking of a dip in the big lake this summer.

What's the water temperature at your favorite lake this weekend? Please send a comment if you have a reading from one of our 10,000+ lakes.

Enjoy the "bathwater" lake temperatures for the next few weeks.

PH

Lake Superior "lake breeze" visible from space

Posted at 5:00 PM on May 20, 2010 by Paul Huttner (2 Comments)
Filed under: Lake Superior, Springtime

Great pictures Thursday from space showing a classic lake breeze near Lake Superior.

Look at the photos below. You can see the areas over western Lake Superior and the surrounding land areas are largely cloud free, except for an area of fog on the lake near Grand Marais.

Looking inland you can see a distinct line of clouds. These are cumulus clouds forming along the lake breeze front. Images are courtesy of the University of Wisconsin Madison MODIS page.

1000 meter resolution MODIS view of Lake Superior Thursday shows cloud free areas near the west end of the lake.
(click on photos for bigger images)

Higher resolution (250 meter) MODIS view. Note the distinct line of cumulus inland paralleling the North Shore.

Arrows on the right show cool dry stable wind flow coming off Lake Superior.
Cumulus cannot develop in this stable air mass. These are the cloud free zones. Arrows from the left show wind flow from the other side. A "convergence zone" is created where the two air flows meet. This is the lake breeze front. Since the air has nowhere to go but up, cumulus clouds form as the air rises.

Lake breezes are caused by temperature differences over land and water. In this case, cool air over Lake Superior is dense and pushes inland during the day as the land heats up.

Thursday's surface map shows the wind direction and temperature differences. Notice how stations near Lake Superior are in the 60s while areas inland are in the lower 80s, nearly 20 degrees warmer!

In Chicago we always forecast "cooler by the lake" on spring and summer days like today. Thursday you could feel it in the air and see the effects from space near Lake Superior.

PH

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