Some sleet out there this evening

I just added this on Facebook, but in case you missed it there….

Don’t be surprised if you see sleet out there this afternoon/evening. No travel problems are anticipated, as surface temps will stay above freezing.

There’s not really a graphic that demonstrates this well, so I added some edits to an existing one. Normally, we would go from sleet to freezing rain. However, our surface temps will stay above freezing. Basically, the rain falls into a very cold, dry airmass. This causes the rain to evaporate. Evaporation is a cooling process, so that layer of air that the rain is evaporating in gets cooler. That eventually leads to temps below freezing in that layer and the rain drops turn to sleet as they fall through it. The sleet pellets don’t have time to melt before they reach the ground, due to our slightly warmer surface layer of air being so shallow. As we go through the evening, the warm air advancing our direction will overcome all of this and give us plain ole rain.

Picture10

The rain has been slow to fall to the surface, since so much of it is evaporating before it reaches the ground. That will change anytime for us in Crossville, as it already has for many folks to our south.

The dynamics are impressive with this warm front, so don’t be surprised if you hear thunder this evening and overnight.

Our temperature is 36 degrees right now.

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