From March to May, Lake Michigan brings a heap of forecasting challenges to Meteorologists in Northern Illinois and Wisconsin. Why does it only happen in these months? Lower Lake Michigan water temperatures are warming...but slower than our weather allows the air to. By the time we get into June, the lake waters are in the 60s and 70s...not cool enough to start the breeze.
When there is stagnant air and little wind, the difference in temperature between the warming land and the cool lake water creates a breeze off of the lake. This breeze accelerates to the west through the cities of Chicago and Milwaukee towards their far western suburbs Elgin and Waukesha. Rarely these breezes make it toward the I-39 corridor, but by the time the breeze moves this far inland it's moderated some and only causes a downward shift of 2-6°F.
A cool front will work in from the north (not a lake breeze front) bringing a shift in the wind on Friday. While our winds will be out of the northeast (and will be cool because of the lake-influence) it's not exactly a "lake breeze." This front will cool all of Northern Illinois and Southern Wisconsin...especially with a wind off of the lake. When it comes to lake breezes, we have to think about why they occur: because of light winds...mainly from March to May.
p.s. You may have heard of "sea breeze fronts." They are basically the same, but sea breeze fronts occur in the summer months... It occurs the same way! When the land heats up, a mini-cool front brings in the slightly cooler air off of the water...and often causes thunderstorms to form along the Gulf coast and Florida. -ERIC
No comments:
Post a Comment