Another Look at the July 22, 2010 Heavy Rain Event in Milwaukee

Very heavy rains affected parts of south-central and southeast Wisconsin during the late afternoon and evening hours of July 22, 2010.  Flash flooding resulted, especially in the Milwaukee Metro Area.   Previously, the Milwaukee/Sullivan NWS Forecat Office generated a summary story on the severe weather and flash flooding of July 22, 2010, which can be found by clicking here.

During the heavy rains of July 22nd, we received a telephone call from the broadcast meteorologist's who work for WTMJ -4 in Milwaukee.  They mentioned that they had measured some 7 inches of  rain over a 2.5 hour period of time.  That's a ton of rain!  So after the dust settled, we asked them to provide us with specific information about rainfall amounts.  WTMJ-4 is located on Capitol Drive north of downtown Milwaukee.  Here is Chief Meterologist John Malan's e-mail reply: 

We are certain that the one-hour rainfall was 6.73 inches between 5:15 and 6:15 in the late afternoon/evening.  I am not sure how much fell before and after that one hour period.  The twenty-four hour rainfall (midnight to midnight July 22nd) was 8.31 inches.  We also received another inch after midnight on July 23rd, so the two day total was 9.31 inches.

We took a look into the record books to find what the Wisconsin records are for 1-hour and 24-hour rainfall amounts.  Here's what we found:

Wisconsin Rainfall Records

1-hour - 7.00 inches, Baraboo, Sauk County, on July 17, 1993

24-hour - 12.70 inches, Baraboo, Sauk County, on July 17, 1993

So, the heavy rains measured at WTMJ-4 in Milwaukee do not break any Wisconsin record.  Besides WTMJ-4 is not an official NWS co-op site.  Weather data from only official sites are considered for record-keeping.  Nonetheless, what happened at WTMJ-4 gives you an idea of just how hard the rain was coming down on July 22nd!


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