Modeled pneumonia front over southeastern Wisconsin, May 16, 2023; see full-size version
map showing motion of pneumonia front of 20–21 May 2008

A pneumonia front is a rare meteorological phenomenon observed in coastal areas of Lake Michigan during spring and early summer. These fronts are defined as lake-modified synoptic scale cold fronts that result in one-hour temperature drops of 16 °F (8.9 °C) or greater.[1] While pneumonia fronts occur primarily in the states of Illinois and Wisconsin, pneumonia fronts are also observed in Indiana and Michigan.

Pneumonia fronts do not necessarily have to be synoptic, or large scale, cold fronts. They are most common between the months of April to July when the temperature difference between the cold lake waters and the warmer air over land can be as much as 35–40 °F (19–22 °C). Under weak prevailing winds, a density current can often develop in the form of a lake breeze that moves from that water to the adjacent shoreline and several miles inland. This "lake-breeze cold front" can drop temperature in places like Chicago, Milwaukee, Benton Harbor, Green Bay, and Traverse City significantly as they cross the area.

History

The first documented pneumonia front was on June 13, 1909, in Michigan City, Indiana.[2][3] The term 'pneumonia front' was coined by the National Weather Service in Milwaukee in the 1960s.[4]

Documented occurrences

The following are documented occurrences of a lake-modified synoptic scale cold front or a "pneumonia front":

Date Location
June 13, 1909[3] Michigan City, Indiana
May 21, 1938[3] Will County, Illinois
June 6, 1967[3] Cook County, Illinois
June 30, 1975[3] Lake County, Indiana
July 1, 1983[3] Kenosha County, Wisconsin
July 17, 2003 Lake Michigan
May 20, 2008 [5] Eastern Wisconsin (Lake Michigan)
May 21, 2008 [6] Eastern Wisconsin (Lake Michigan)
May 26, 2008[7][3] Cook and Lake Counties, Illinois; Lake and Porter counties, Indiana
April 25, 2009 [8] Cook and Lake Counties, Illinois
June 1, 2009 Cook and Lake Counties, Illinois
April 21, 2010 Cook, Lake and Will Counties, Illinois; Lake and Porter Counties, Indiana
May 13, 2011 Cook, Lake and Will Counties, Illinois; Lake and Porter Counties, Indiana
March 15, 2012 [9] Cook and Lake Counties, Illinois; Lake County, Indiana; Milwaukee, Racine and Kenosha Counties, Wisconsin
April 13, 2014 Cook, Lake and Will Counties, Illinois; Lake and Porter Counties, Indiana
May 27, 2014 Cook, Lake and Dupage Counties, Illinois; Milwaukee, Racine and Kenosha Counties, Wisconsin
September 29, 2014 [10] Cook, Lake, Dupage and Will Counties, Illinois; Milwaukee, Racine and Kenosha Counties, Wisconsin
March 24, 2017[11] Cook, Lake, Dupage and Will Counties, Illinois; Milwaukee, Racine and Kenosha Counties, Wisconsin
April 10, 2017[12] Waukesha, Milwaukee, Racine and Kenosha Counties, Wisconsin
June 1, 2018 Cook County, Illinois; Porter County, Indiana
May 3, 2020[13] Northeast Illinois; Milwaukee, Racine, and Kenosha Counties, Wisconsin
April 27, 2021[14] Cook County, Illinois; Lake, Porter, and LaPorte Counties, Indiana
May 10, 2022[15] Emmet, Charlevoix, Grand Traverse, and Leelanau Counties, Michigan
June 17, 2022[16] Milwaukee County, Wisconsin
April 14, 2023[17] Grand Traverse County, Michigan
May 16, 2023[18] Southeastern Wisconsin, Northeastern Illinois

See also

References

  1. ↑ Adrian, Bart (May 27, 2008). "Bart_Adrian's Blog". Archived from the original on October 11, 2007. Retrieved May 27, 2007.
  2. ↑ "REAL or FAKE?: The 'pneumonia' front". News 5 Cleveland WEWS. May 17, 2023. Retrieved December 21, 2023.
  3. 1 2 3 4 5 6 7 "The Impromptu Weather Blog". May 27, 2008. Archived from the original on July 13, 2011. Retrieved May 27, 2007.
  4. ↑ Skilling, Tom (May 27, 2008). "WGN Weather Center Blog". Retrieved May 28, 2007.
  5. ↑ "Did You Feel the Pneumonia Front Last Night?". Archived from the original on September 7, 2008. Retrieved August 2, 2008.
  6. ↑ "It Happened Again Last Night...Another Pneumonia Front!". Archived from the original on May 30, 2008. Retrieved August 2, 2008.
  7. ↑ Bachmeier, Scott (May 27, 2008). "Lake Michigan "pneumonia front"". CIMSS Satellite Blog. Retrieved May 16, 2023.
  8. ↑ "Chicago Tribune". April 27, 2009. Retrieved April 25, 2009.
  9. ↑ "Another day, another record broken as warm spell shines on". Chicago Tribune. March 15, 2012. Archived from the original on March 16, 2012. Retrieved March 16, 2012.
  10. ↑ "Brace for the 'pneumonia front:' Skilling says jarring 20-30 degree temp drop to hit tonight". September 29, 2014. Archived from the original on October 6, 2014. Retrieved September 30, 2014.
  11. ↑ "March 23-25, 2017: Impressive Day-to-Day Temperature Change, Including a Near-Record Quick Dropdate".
  12. ↑ "FOX6 Weather on Twitter". Twitter. Archived from the original on April 22, 2017. Retrieved April 11, 2017.
  13. ↑ "US National Weather Service Milwaukee/Sullivan Wisconsin on Facebook". Facebook. Archived from the original on April 30, 2022.
  14. ↑ ""Pneumonia Front" comes down Lake Michigan". April 28, 2021. Archived from the original on May 1, 2021. Retrieved May 1, 2021.
  15. ↑ "Check this out! After setting a record high of 92 this afternoon, Traverse City dropped 31 degrees in 10 minutes (88 at 6:35pm to 57 at 6:45pm) after a northerly lake breeze pushed through, dramatically cooling the area. #miwx". May 10, 2022. Archived from the original on May 11, 2022. Retrieved May 11, 2022.
  16. ↑ "Well MKE did it, at 5:55pm the temp was 82 and by 6:50pm the temp had dropped to 66 resulting in a 16° drop in temps in under an hour. Can officially label this a Pneumonia Front. #wiwx". June 17, 2022. Archived from the original on June 18, 2022. Retrieved June 18, 2022.
  17. ↑ "Notice a drastic change in temperature at any point today? Conditions were favorable for the development of lake breezes this afternoon. As a matter of fact, Traverse City fell from a record-breaking high of 86°F at 4:30pm to 61°F by 6:30pm... a 25°F decrease in two hours! #MIwx". April 14, 2023. Archived from the original on April 15, 2023. Retrieved April 15, 2023.
  18. ↑ Salgado, Beck Andrew (May 16, 2023). "A 'pneumonia front' expected to drop temperatures 20-30 degrees in a matter of minutes on Tuesday". Milwaukee Journal Sentinel. Archived from the original on May 16, 2023. Retrieved May 16, 2023.

Further reading

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