Today proved to be a cold day in Central Indiana. Temperatures only reached the low 20's this afternoon but it never felt like that. Wind chill values were below 10°F all day long. Temperatures will continue to drop overnight as more polar air moves into the area thanks to high pressure. As you can see from the map below, the wind direction continues to support the movement of cold air. This wind will also continue that lake effect snow that has been going on all day in the northern part of the state.
Skies should also be clear overnight and this will allow rather significant radiational cooling. This basically allows the surface heat to easily escape into the upper atmosphere and we end up with cold temperatures. The ONLY thing helping us tonight is the wind. Normally, temperatures drop even more severely under calm winds. Since we are expecting winds at 10-15 mph, this will continue to "mix" the atmosphere and keep the temperature up slightly. Regardless, it's going to be a cold morning. Here's what the temperature should feel like throughout the night.
Honestly, the computer run that produced this "feels like" forecast is a little conservative to me. I think it will actually feel more like -5°F to 0°F by 7 AM Sunday. The computer run did have the right wind speeds in the formula but it was keeping our overnight low in the mid teens, and that doesn't seem likely under clear skies.
Temperatures pop back into the low 30s on Sunday thanks to the sunshine. Clouds return on Monday and eventually snow will begin in the evening. The best chance of snow is Monday night into Tuesday morning. This would be the best window for any accumulating snowfall. Model runs this evening are pointing at less than an inch of snow in Central Indiana for the event.
