The temperature took a dive Thursday but not because a cold front swept the state, the remnants of the early morning fog kept clouds around and temperatures responded.
Early Thursday a gentle wind shift to the northeast occurred but it wasn’t a full blow frontal passage. The shift in winds allowed some cooler air to undercut the warm/humid air late last night bringing on fog that became quite thick before sunrise. The fog dissipated but the the skies never fully cleared leaving a low layer of cloud cover over Indianapolis and over some portions of central Indiana Thursday.
The layer of clouds are only 1000 feet up and only 1000 feet thick but it is enough to retard sunshine and prevent temperatures from rising. A solid overcast can hold afternoon temperatures down a full 15-degrees but also keep nighttime lows up just as much.
Today was a perfect example of how in just a matter of only a few miles the weather can look and feel so much different. Below are the images from our cameras in Bloomington and Columbus, where the afternoon temperatures were will into the 80s. In fact the heat index reached 90-degrees.
THe image below is from the visible satellite Thursday afternoon. Note the areas of black – this is where there are no clouds. It is very evident how the low clouds were hanging on over the central part of the state.
That low cloud deck never fully dissipated and that will lead to more fog overnight into Friday morning. Be prepared for some patchy, dense fog early Friday. Below is a forecast vertical profile of the atmosphere through early Friday morning. This indicates that low clouds and fog will thicken overnight below 2000 feet down to the surface then dissipate slowly after 10 am Friday morning. Use caution if travelling early Friday and be sure to check with Fox59 early in the morning for the latest conditions.