Sunshine and the lake breeze

After a long stretch of dreary weather with lots of dense fog last week, the sun is going to dominate the forecast the next five days. This is good timing to coincide with Daylight Saving Time. Hopefully, all of you have set your clocks one hour ahead. Our sunset today is 6:57. With the sunny forecast try to take advantage of that extra hour with a walk after work.

This time of year we begin to talk about, “cooler near the lake” all the time. Lake Michigan takes a very long time warming up in the spring. Water is much more dense than the land, so the land heats up much more quickly than water does. Take a look at the current lake temperatures.

These temperatures are taken from space in a process known as remote sensing. The satellite can decifer what temperatures are on the surface of Lake Michigan using infra-red radiation. If there are clouds around, the sensor will not work correctly. On the image above, you can see the black color represents cloudy conditions. Where it was clear the lake water on the surface of Lake Michigan is between 35 and 37 degrees.

Because the lake stays so cold, on a sunny calm day a small area of high pressure develops over the lake. As the sun warms the land, a small area of low pressure develops there. Wind always blows from high to low pressure so a lake breeze develops. This often means the warmest temperatures near the lake happen in the mid-morning before the lake breeze develops. Once the lake breeze starts to move onshore, the temperatures can rapidly drop. If you live within a couple miles of Lake Michigan you know exactly what I am talking about. That is why Waukesha is much warmer than Milwaukee in the spring.

Take a look at today’s surface map.

Sunday was not a typical lake breeze day, but with a prevailing northeast wind, the temperatures stayed cooler near the lake.

This week will bring sunshine galore, but it will be cooler near the lake for much of the week. In order for the lake breeze to not occur, there needs to be a northwest, west, or southwest breeze greater than 10 miles per hour. If this occurs, the lake breeze will not move onshore. This is possible on Thursday and Friday, when everyone in southeast Wisconsin will have highs in the fifties. Thanks for reading and enjoy the beautiful week.

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4 Responses

  1. Interesting. Stands to reason, but never thought about that. Nice blog!

  2. Finally, someone was able to answer the question I’ve had for years, “Why do we get so much east wind here in springtime?” I’ve never gotten a satisfactory answer to that question until reading this blog. Thanks for explaining the springtime phenomenon and how that all works. You wouldn’t believe some of the answers I’ve gotten to that question!

  3. Learn something new every day Thanks

  4. Thanks for reading and I’m glad I was able to answer some questions.

    Mark

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