The Lake Michigan Blanket Effect
We all know that Lake Michigan affects our weather in the snow department, but did you know temperatures can also vary quite widely across the area thanks to the lake?
What it comes down to is your proximity to the lake. Depending on cloud cover, precipitation and especially wind speed and direction, communities that sit closer to the lake's relatively warm water may see a "blanket effect."
As wind blows over the lake, some of that "warmer" air can be picked up and carried inland as clouds and lake effect precipitation. And where those clouds exist, temperatures and wind chills do not get quite as low as they would if you were farther from lake -- or if there was no lake present at all.
A perfect example of this phenomenon occurred earlier this morning. The areas due south of Lake Michigan seeing less intense cold as opposed to locations like South Bend. The spots where the temperatures aren't as cold were seeing lake effect cloud cover, thus keeping their temperatures up just a little bit.
In Chicago, the clouds from the lake -- and the resulting snow -- did not arrive until sunrise. That allowed their temperatures to drop all the way down into the upper teens, which only enhanced the snowfall they saw.
So the next time your car thermometer reads 5-10° warmer at your house than at your workplace, your house could have been in an area affected by lake effect cloud cover, or a thermal blanket!