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More Freezing Rain? How Does It Form?

by Steve Templeton

KMOV.com

Posted on December 16, 2008 at 5:33 PM

Updated Wednesday, Nov 4 at 3:29 PM


Kent and I have been looking at a storm setting up for Thursday that likely will produce an ice storm in the Midwest. It looks like the ice storm is going to be North of St. Louis. An area North and South of a line from Quincy, IL to Peoria to Chicago seems to be the target for this ice accumulation. Here in the St. Louis area it will start out below freezing Thursday morning with pockets of light freezing rain that then should turn to all rain in the afternoon as temperature warm above freezing.

However, Kent and I have noticed at least one forecast model that wants to keep our temperatures below freezing until late afternoon Thursday. If that's the case, it's possible we could see more freezing rain and later into the afternoon. That's why we've been telling people who have travel plans Thursday afternoon to watch for updates. But as of now (Tuesday) we think the more signifcant ice will be North of the St. Louis area.

With all this talk about freezing rain, you may be wondering exactly how this wintry type of precipitation forms?

I think this graphic below explains it well. The key is that temperatures at the surface are below freezing and above the surface temperatures are above freezing. That warm air aloft makes any precipitation melt into rain. But as the rain falls to the ground, the below freezing air at the surface causes the rain drop to freeze on trees, power poles, or anything that is below freezing. Sometimes these rain drops freeze before they hit the ground, that's called sleet.

fzra_sound.gif

We're looking for changes in the new forecast models, so tune in to News4 or check out our video forecasts right here on KMOV.com for the latest updates.

Templeton Out!

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