The central Midwest just passed the 25th anniversary of arguably the worst short term heat wave in its history. July 12-16th of 1995. A vicious combination of heat and humidity literally boiled the region with heat index values that reached 131 degrees in Cedar Rapids (100 temperature/ 86 degree dew point). In Chicago alone, more than 700 people died from heat related causes.
At the time I was working in the Quad Cities when the afternoon of the 13th the heat index (how it feels when the heat and humidity is combined) peaked at 125 degrees. The thing I vividly remember is walking out of KWQC's air conditioned building into a wall of steam equivalent to a sauna. My body instantly began to perspire and my glasses fogged up so badly I couldn't see through the lenses. Aside from that there was essentially no breeze which usually adds at least a small measure of cooling. Not that afternoon. It was incredibly oppressive and to this day it remains the hottest weather I've ever experienced.
In Iowa agricultural losses approached $6 million. Losses were placed at 4,000 head of cattle, 370 hogs, 1,250,000 chickens, and 250,000 turkeys. On one Webster County farm alone 250,000 laying hens perished on the 2nd day of the heat. Another egg producer had 1.5 million laying hens on two farms, one in Winterset, the other in Guthrie Center. They reported a loss of at least 500,000 hens. Disposal became a serious problem as rendering plants were overwhelmed.
In addition to problems caused to humans and livestock, there were numerous heat buckles reported on streets and highways around the state. Remarkably, there was little in the way of crop damage. The combination of light winds and extremely high dew point temperatures helped keep the crops from stressing too much. Heavy dew would form overnight that would last well into the early afternoon hours.
Looking at the majority of heat waves in Midwest history, we find that we're currently in the favored climatological time of year for such events to occur. Another remarkable stretch of brutal and unrivaled heat scorched the Midwest in July of 1936. In Burlington, Iowa record highs were established on 14 consecutive days...most every record 105 degrees or more. You can see the records that were established in some major cities around my area.
Not surprisingly, 1936 set the record for the warmest summer on record in both Iowa and Illinois.
Being in that favored time period for heat, the table is now set for some very toasty conditions this weekend, especially Saturday. You can see the favored 500mb pattern and its heat dome centered just to our southeast.
In this case, it brings just one day of extreme highs into the 90s over my area with dew points reaching the upper 70s. That results in widespread heat index's of 100-105, perhaps as warm as 107 in a few spots. That will result in the issuance of a heat advisory at some point from the NWS.
As for thunderstorms, the warm air aloft should cap the mid levels and keep things quiet until scattered storms form along a weak boundary late Saturday night or early Sunday. These look pretty hit and miss until better dynamics arrive Monday night and Tuesday. Have a solid day and by all means enjoy the weekend ahead. Roll weather....TS