This is just a new index to show you have weather could affect your daily life, in general.
Although there will be some fog around tomorrow morning (generally before 9 a.m.), other than a couple isolated showers in the afternoon (peak of 20% coverage), there will be little disruption to your life, via the weather, tomorrow.
Wednesday looks okay, it's just going to get warmer.
Only reason Thursday is very low is that a cold front will pass morning-midday with a few spotty showers & t'showers with peak coverage around 30%. This could briefly disrupt any activities you have in the morning.
Friday definitely looks like no issues with low humidity & comfortable temperatures.
On July 23, 1947, an incredibly potent & rare cold snap brought the coldest July weather since 1863 (Rensselaer dropped to 40 July 16, 1863 during a major drought) to the area.
Rensselaer & Wheatfield dropped to a cold 41 on this date. Rochester had a low of 42, Whitestown 43, West Lafayette & Marion 45.
Interestingly, August was very hot with numerous days in the upper 90s to +100. Kokomo hit 100 or greater 4 times in August, including 106 on the 6th, while Crawfordsville & Wheatfield hit 100 on August 6th. West Lafayette hit 101 on August 22. Marion hit 100, 101 & 102 on the 4, 5& 6th.
So, what was behind such a cold, cold night (relatively-speaking) for late July?
You can see in the July 22 & 23 surface maps (at 1:30 a.m.) that unusually strong surface high pressure was present over the Northern Plains to Corn Belt. Also, note the strong surface cold front deep into the Gulf of Mexico. This is highly unusual for mid-July to get such a cold (or any cold front for that matter) so far south. Synoptically-speaking, such a map resembles early October more than late July.
Also, notice how dry it was. There were rainfall deficiencies over a large area (including our area) with powdery-dry soils. This caused the nights to be even colder. There was dry air not only with the chilly Canadian airmass, but the soils & withering vegetation only made it drier. Lack of water vapor on clear, calm nights with strong surface high pressure, causes alll heat to be lost. There is little water to store any heat energy. So, temperatures tank. They may warm up 40 degree between morning & afternoon in such dry conditions, too. Dry air also tends to heat up quickly. So, you have large differences in the daily high & low, even during the shorter night-time hours of summer with these conditions.
So, it likely would not have gotten so cool at night had there been more rainfall prior.
We also probably had all the birds in a row with a Phase 8 MJO, a negative NAO & AO & a massive ridge over Alaska & the Pacific that led to such cold.
In fact, the Fairbanks, Alaska airport hit 88 on July 16. This occurred amidst 9 of 12 days hitting the 80s. Interestingly, as the ridge moved east & southeast, Fairbanks reached just 54 on August 3 & 5 of 6 nights August 3-8 saw patchy frost with lows in the mid to upper 30s.
So, as what often happens, the massive upper ridge moved eastward & set up over our area with those droughty soils & a very hot, dry August & September occurred with multiple days of 100s in the area. Meanwhile, it was quite cool in Alaska, even by their standards.