Temperatures start to climb as do our chances for rain in the next 36 hours. After a pleasant day with temperatures in the 70°s Monday, we should see the mercury rise in to the upper 70°s to lower 80°s Monday afternoon.
A weather system to our west will begin to impact weather conditions in central Indiana starting Tuesday. A few showers and thunderstorms are expected to get started late morning in to early afternoon.
The forecast simulation above shows the rain developing by noon. Then spreading east/northeast. If thunderstorms can get going, a few of these could be strong, producing gusty winds, heavy downpours and small hail.
Computer models suggest a line or two of thunderstorms passing through central Indiana late Tuesday night through early Wednesday morning. These will also have a chance at producing gusty winds, heavy downpours and small hail. Due to how much moisture is projected to be in the atmosphere, I think the largest impact will be heavy downpours if you get caught under a thunderstorm. A heavy amount of rain can be produced in a short period of time.
The Weather Prediction Center, a forecast agency for NOAA, has central Indiana in a "Slight Risk" for the potential of flash flooding Tuesday evening through Wednesday morning. The latest flash flood guidance suggests 2.3" to 3" of rain in 3-hours could produce flash flooding in central Indiana.
THE HEAT IS ON
Just as the late Glenn Frey sang, "The heat is on" later this week. We've been talking about it for several days. Upper-level high pressure will move from southwest Texas/New Mexico and move through the Mississippi River Valley and in to the Ohio River Valley later this week.
How it works: As high pressure moves overhead it pushes air down to to the surface of the earth. Air is a gas. As you compress a gas, it heats up. Same thing happens with the air. As it compresses against the ground, it begins to heat. Bring the upper-level high overhead, a "hot dome" develops taking temperatures soaring.
In our case, temperatures are currently forecast to reach the middle 90°s. Combine that with a very humid air mass - dew point temperatures will be in the lower to middle 70°s - and you get heat index values in to the triple digits.
Right now it appears the heat index could top out around 105° to 106° Friday, Saturday and Sunday. If this works out, this will be the highest heat index temperature (feels like) of 2018.
I do think some locales have the potential to climb in to the upper 90°s. That will greatly depend on a few things including cloud cover, whether or not a few thunderstorms develop, and exactly how humid it gets. (Humid air does not heat as easily as dry air.) Stay tuned!