Some of the coldest July temperatures in central Indiana in over a decade are possible tonight. The record low of 54° (set in 2004 & 1971) will very likely be eclipsed between 6am-7am Sunday morning… as I’m forecasting 50° for the low in the city. Notice many locations away from Indy’s urban heat island will be in the 40s… well below the average low of 65°.
“If” Indianapolis drops below 50° it would be the first sub-50° temps in July since 2001. Regardless it will be the talk of the town in the morning, and sets the stage for one of the coolest Brickyard 400 race days ever.
If you’re going to the track early I recommend a light coat. A sunny sky will give way to a building cumulus field that turns the sky to party sunny by early afternoon.
The coolest Brickyard 400 race day high of 73° in the inaugural race of 1994 will be rivaled. So will the record low maximum that was set in 1928 and 1925 at 72°. Bottom-line this is an impressive cool air mass for late July standards… and more indicative of late September or mid-May.
FutureTrak 13 shows the building cloud deck during Sunday afternoon. While likely overdoing late afternoon precipitation…don’t be surprised to see isolated “instability” showers especially north of I-70. This is due to a rather large temperature difference between the surface and much colder air aloft that creates robust lapse rates in the atmosphere.
The air mass remains unseasonably cool into Monday, before modifying by mid-week. Rain and storm chances also return with the warm up.