The term Pneumonia front, first coined by Milwaukee Weather Bureau Office in the 1960s, is used to describe a rare meteorological phenomenon observed on the western Lake Michigan shoreline during the warm season. These fronts are defined as lake-modified small scale cold fronts that result in one-hour temperature drops of 16 °F or greater. They do not necessarily have to be large scale, cold fronts to bring weather changes to an entire region. Very often in the spring to early summer the temperature difference between the cold lake waters and the warmer air over land can be as much as 35–40 °F . Under weak prevailing winds, an air current can often develop in the form of a lake breeze that moves from that water to the adjacent shoreline to as much as several miles inland. This "lake-breeze cold front" can drop temperature in places like Chicago, Milwaukee and Green Bay significantly as they cross the area. There has been many a spring day at Wrigley Field that surprises Cub fans who may have travelled from an inland location toward the shore to take in an afternoon game at Wrigley just a few blocks from the lakeshore, only to feel the effects of the "pneumonia front" as that cold blast of air comes through. On May 26, 2008 such a front caused temperatures to drop in Chicago from 72 at 10 pm to 55 an hour later. Winds had gone from light and westerly to northeasterly with gusts up to 40 mph along the lake. Other areas along the lake dropped from the mid 76 to the upper 40s
Hosted on Acast. See acast.com/privacy for more information.