[6:52 PM] We have seen lots of questions today about how sleet forms when it's very cold at ground level. The answer is that the air is actually much warmer about a mile above the ground.
— NWS Wilmington OH (@NWSILN) February 15, 2021
We're measuring exactly how warm with our evening weather balloon launch! pic.twitter.com/6esyeEyTvF
The NWS said that the sleet was due to a layer of much warmer air, about a mile up.
After launching a weather balloon Monday evening, the NWS found around 6,000 feet up, the air was almost 20 degrees warmer, at 37.4 degrees. The warmer air above the ground causes falling snowflakes to melt or partially melt, then refreeze when they fall into the very cold air below, creating sleet.
Sleet caused some areas to see reduced snowfall totals versus what forecast models had predicted.
[7:31 PM] This chart is a great guide that shows the way that different wintry precipitation types can develop. https://t.co/ULGHazENh8 pic.twitter.com/OElFAevu9Z
— NWS Wilmington OH (@NWSILN) February 16, 2021
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