Summary of the July 17 - July 21 Heat Wave in South-central & Southeast Wisconsin (updated 2 pm 8/8)

 ***Updated for number of fatalities....total of 5 for all of Wisconsin***


Quick Facts:

What: Long-duration heat wave with heat index (HI) temperatures exceeding 105.  Max HI values of 110-114. Maximum air temperatures in the 90s, with highest reading of 100 at Janesville and Middleton on July 20th.

Where: South-central and Southeast Wisconsin.

When: July 17-21, 2011.

Fatalities:  3 confirmed in the County Warning Area serviced by WFO Milwaukee.  One in Columbia County - 65-year-old man near Fall River, on Monday, July 18th.  Second one in Marquette County - 80-year-old man who was staying at his secondary home. Date of death unknown.  Third one in Sauk County - 87-yr-old women found in her un-airconditioned trailer near Reedsburg.  Authorities are still investigating other deaths to determine if they were related to heat.

[Authorities confirmed a heat-related death in Crawford County - an 82-year-old woman, and 65-year-old women in Monroe County who passed away on July 23rd. This makes 5 confirmed, heat-related deaths in Wisconsin].

 

[The heat-related fatalities in 2011 are the first in Wisconsin since the 2006 summer]

Injuries: Probably 200-300 people provided medical treatment at clinics or hospitals due to effects of heat.

Additional Impact: Many cooling centers opened. Some outdoor activities were postponed or moved indoors.  Summer school classes were canceled in several cities for a day or two. Reports of buckled roads due to heat expansion. At least one roofing company in Madison didn't send crews out Monday through Wednesday.


South-central and southeast Wisconsin experienced a long-duration heat wave from Sunday July 17th through Wednesday July 20th.  However, the area near Lake Michigan did have a 1-day reprieve on Tuesday, July 19th.

The combination of maximum temperatures reaching well into the 90s and dewpoints peaking in the 70s to 80 resulted in oppressive heat index temperatures, also known as apparent temperatures.  Maximum heat index temperatures exceeded 100 on all four days west of State Highway 83.  Additionally, overnight minimum temperatures remained above 70 for the most part away from Lake Michigan. 

Highlights and graphic for each day:

Sunday July 17th

Minimum pre-sunrise air temperatures ranged from 63 in Burlington to 74 in Middleton.  Maximum air temperatures ranged from 91 in Waukesha and the Baraboo-Dells Airport to 97 in Kenosha, Janesville, and Middleton.  Maximum heat index temperatures ranged from 98 at Port Washington to 109 in Fond du Lac and Portage. Below is a graphic showing maximum heat index values across Wisconsin.  Click on image for larger version.

July 17th heat index graphic

Monday July 18th

Minimum pre-sunrise temperatures ranged from 71 in Sheboygan to 81 in Janesville and Middleton.  Maximum air temperatures ranged from 90 in Waukesha and West Bend to 97 in Watertown.  Maximum heat index temperatures ranged from 100 at Port Washington to 114 in Middleton and at Timmerman Field in Milwaukee to 114 in Middleton. Below is a graphic showing maximum heat index values across Wisconsin.  Click on image for larger version.

July 18th heat index graphic

Tuesday July 19th

Minimum pre-sunrise temperatures ranged from 68 in Burlington to 79 in Monroe.  Maximum air temperatures ranged from 85 in Milwaukee to 97 in Janesville. Maximum heat index temperatures ranged from 90 in Milwaukee to 108 at the NWS Forecast Office 3SE Sullivan. Below is a graphic showing maximum heat index values across Wisconsin.  Click on image for larger version.

July 19th heat index sc and se wi   July 19th heat index WI

Wednesday July 20th

Minimum pre-sunrise temperatures ranged from 70 in Fond du Lac, Waukesha, and the Baraboo/Dells Airport to 77 in Monroe.  Maximum air temperatures ranged from 93 in Waukesha to 100 in Janesville and Middleton.  Maxim heat index temperatures ranged from 103 in West Bend to 110 in Kenosha, Racine, Sheboygan, and the NWS Forecast Office 3SE Sullivan.  Below is a graphic showing maximum heat index values across Wisconsin.  Click on image for larger version.

July 20th heat index sc and se WI  July 20th heat index WI 

Thursday Morning July 21st- through 4 am

Air temperatures during the Wednesday overnight hours ending 4 am Thursday morning remained well above normal. They ranged from 75 at Juneau to 83 in Milwaukee.  These overnight hours were part of the heat wave.  After sunrise a weak cold front moved southeast through southern Wisconsin and ushered in drier and slightly cooler air. At 322 am Thursday, July 21st, the Excessive Heat Warnings and Heat Advisories were cancelled, except for a Heat Advisory through 7 pm CDT Thursday evening for the counties of Lafayette, Green, Rock, Walworth, Racine, and Kenosha. However, the remaining Heat Advisories were canceled at 307 pm CDT in the afternoon. Maximum heat index temperatures during the day Thursday reached the 100 to 102 range near the Illinois border.


Temperatures for July 17-21st

The following table shows record high temperatures...plus record high minimum temperatures...for Milwaukee /MKE/ and Madison  /MSN/...along with observed high and low calendar-day temperatures from these sites.

          MKE RECORDS            | MSN RECORDS |          MKE      MSN
-----------------------------------------------------------------------
      MAX        HI            MAX         HI                OBSERVED   
DAY   HI  YEAR   MIN  YEAR      HI  YEAR   MIN  YEAR      HI LO   HI LO 
-----------------------------------------------------------------------
17    98  1942   79   1931      98  1936   80   1958      95 72   96 72
18    97  1991   77   1942      95  1894   77   2011      95 74   93 77
19    98  1932   79   1935      97  1964   79   1929      85 74   95 74
20   100  1930   78   1991      97  1930   76   1934      98 74   97 74
21    99  1983   78   2002     104  1901   79   1901      94 79   88 74


Consecutive Days with Maximum Temperatures 90 and Above

Milwaukee:

Consecutive days with high temperatures of 90 degrees or warmer

Record: 10 days in a row ending 9/3/1953

Streaks in past 30 years:

Days  Ending Date
6     8/2/2006
5     6/18/1994
5     8/27/1993
5     8/30/1991
5     7/9/1988
5     6/22/1988
4     7/3/2002
4     6/25/2002
4     10 more periods between 2001 and 1983

Most recent period of hot weather was 3 days in a row of 90 degrees or greater on June 6/7/8 of 2011.

Madison:

Consecutive days with highs of 90 degrees or greater
Record: 15 days in a row ending 7/27/1901

Streaks in past 30 years:

Days  Ending Date
9     7/10/1989
9     8/4/1988
8     6/24/1995
6     8/30/1991
6     7/9/1988
5     8/14/1995
5     7/15/1995
5     6/18/1994
5     7/23/1987
4     7/21/2011

4     8/2/2007
4     8 more periods between 2005 and 1983
 


Definitions of Heat-related Advisories and Warnings

An Excessive Heat Warning may be issued under two different circumstances:

 1) If daytime Heat Indices are expected to equal or exceed 105 while night time Heat Indices are 75 or higher for a 48-hour period; 

 2) If the Heat Index reaches at least 100 during the daytime for at least 4 days in a row.

 A Heat Advisory may be issued under two different circumstances:

 1) If the daytime Heat Index is expected to reach at least 100;

 2) If the daytime Heat Index is expected between 95 to 99 for at least 4 consecutive days.

 Please keep in mind these products are issued on a county basis and we will issue based upon the conditions of the majority of the county. 



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