Bart_Adrian's Blog

It's not a technical term. You won't find it in the AMS Glossary of Meteorology. But it is real!

Last night the official Milwaukee temperature at Mitchell International fell suddenly from 56 degrees at 10pm to 43 degrees at 11pm. The wind went from the west at less than 10 mph to the north-northeast gusting over 30 mph. That was the passage of a "pneumonia front"! Here's more about it from our local National Weather Service-Milwaukee/Sullivan...

Tuesday evening:

If you were outdoors near Lake Michigan between 7 pm and 1 am, you probably felt the effects of this "Pneumonia Front."  After the front passed through, gusty northeast winds to 25 to 40 mph ushered in much colder air which lowered temperatures from the mid 50s to lower 60s down to the low to mid 40s within 15 to 30 minutes!  It has happened before...and it will happen again!

We received an email from a weather observer/spotter from Sheboygan concerning this first "Pneumonia Front"....here it is:  Reference the article on your website, I can attest to this front when it moved through.  I was coaching a soccer game and prior to the front, we had a wind out of the NW and it was probably in the low 60’s at the time.  Suddenly the front came, wind switched to NE and a big gust that blew through kicking up dust and anything not tied down.  The kids on the bench grabbed for their warm team coats.  I threw another layer on too.  Although I did not have access to a thermometer at the time, I’m sure the temp did drop about 15 degrees, then add the wind-chill effect.  I would say it was around 8pm when this happened.

The fast movement of the front is related to the smoother water surface which has less friction than land, and the cooler air behind the front is refrigerated even more by the cooler water temperatures.  Sometimes this front will be highlighted by a low cloud band, which looks like a snowplow, that forms along the leading edge.

Below is a simple graphic showing the progression of the pneumonia front down Lake Michigan and nearby inland areas.

Here is a summary of peak wind gusts and the time at selected locations along the Lake Michigan shoreline:

Sheboygan Airport - 758 pm - 31 mph, Sheboygan harbor - 8 pm - 40 mph, Port Washingon harbor - 9 pm - 32 mph, Milwaukee Mitchell Field - 952 pm - 31 mph, Milwaukee Coast Guard - 10 pm - 30 mph, Racine Airport - 1019 pm - 31 mph, Kenosha Airport - 1053 pm - 26 mph, Kenosha Coast Guard - 11 pm - 28 mph.