Cold fronts move through most of the United States on a regular basis, but there is one specific type of cold front that is unlike many others that sweep across the country, and it has a unique name as well.
A pneumonia front is a localism originating from the Midwestern U.S. that describes when cold air over Lake Michigan rushes inland, causing templates to drop dramatically. The rapid decline in temperature can also be accompanied by clouds and rain showers.
“A lake charged cold front (sometimes called a pneumonia front b/c of dramatic temp fall with it) will blow in off the lake late Tuesday. Near the lake, temps could fall from near 80 into 50s in minutes, with a more subdued temp fall expected the farther inland the front gets,” NWS Chicago said of the pnemonia front on Twitter.
While it sounds like another viral term like bomb cyclone or supermoon, which have been used on social media in recent years, the phrase pneumonia front has been used by meteorologists in the Midwest for decades.
In late spring, a pneumonia front can quickly transform the weather from warm and sunny to damp and chilly in less than an hour. In extreme cases, the mercury could plummet more than 20 degrees in a matter of minutes. Since the event is related to Lake Michigan, this specific type of cold front can only happen in Wisconsin, Illinois, Indiana and Michigan.
“The bigger short-term headline is obviously the backdoor lake-enhanced cold front that will result in a rapid drop in temps this afternoon,” said the meteorologists with the National Weather Service office in Chicago in a written statement.
A pneumonia front is making headlines in the Midwest this week, as one will cause the temperature to plummet in Milwaukee, Wisconsin and Chicago.
After temperatures in Milwaukee reached the mid-70s at midday Tuesday with an AccuWeather RealFeel® Sun of around 80 degrees Fahrenheit, temperatures were forecast to drop throughout the afternoon. By sunset, temperatures will reach the low 50s with an AccuWeather RealFeel® Sun in the 40s.
The pneumonia front will have staying power in the Windy City. A high temperature in the mid-60s is forecast for Wednesday after temperatures there topped out around 80 degrees Tuesday.
“Its really stems from seeing a pretty dramatic temperature drop in a matter of minutes to maybe an hour or two,” said Jake Petr, a meteorologist at the National Weather Service in Chicago. “Around 5 o’clock it’s starting to get in far northeast Illinois. Our forecast is 78 degrees there. The next hour it’s 61 degrees.”
Produced in association with AccuWeather
Edited by Alberto Arellano and Joseph Hammond