You may have noticed that the radar showed some rather heavy precipitation on parts of the Cumberland Plateau and East TN yesterday evening. The strange thing is that very little of this rainfall was actually making it to the ground. The reason for the “bright” colors on the radar is that the freezing level was really low yesterday, around 8-9,000 feet, and the precipitation forming at or falling through that level was freezing into big snowflakes. The radar beam from Morristown was intercepting those flakes. Ice crystals cause the return signal from radar to appear very bright. We call this “bright banding”.
All of those snowflakes melted long before hitting the ground and most of the precipitation yesterday even evaporated before hitting the ground. That’s common in cool, dry air masses like we had in place most of the day. We call the precip that evaporates before hitting the ground virga.
I heard several people say the sky yesterday looked like a snowy sky. Well, it was snowing just a couple miles above our heads! Before you know it, we’ll be seeing those glorious snowflakes here at the surface. 🙂
Below is a radar image of the snowflakes seen by radar. All info is compliments of the NWS Morristown Office.