Sunday, January 16, 2011

Wintry Weather This Week?

We're going to see some rain chances over the next 24 hours, but I'm watching Thursday! We could be dealing with a decent round of sleet or freezing rain. Remember, sleet is frozen before it hits the ground and is seen as little pieces of ice. Freezing rain falls as liquid, does not have time to refreeze, and glazes the ice on all exposed surfaces.

The above timeline is using a program called BUFKIT and the time goes from right to left. The first series of green lines is the chance of rain through Tue AM. The second, more colorful series of bars would be the time period I am more concerned about this week. BUFKIT is showing rain... changing to a decent does of freezing rain/sleet... and then maybe an inch of snow. So, why ice? Take a look at the forecast sounding for 1AM Friday morning:
Consider this a vertical slice of the atmosphere at 1AM Friday morning. The red line is the temperature as you go UP through the atmosphere.The diagonal lines show the temperature and I marked the freezing line with light blue.Everything to the left of the blue line is freezing.

So, the precipitation starts as snow. As it falls, it hits a layer "above" freezing between 3600'-8300', which I marked with the yellow lines. THEN, it goes back into freezing air. If it has time to refreeze, it falls as sleet. If it does not refreeze, it hits exposed surfaces as water and freezes, forming a glaze. Either way is not great, but sleet does not cause as much of a problem!

This is just a model, but something we're going to watch closely! We've had a "Wintry Mix" in the forecast for Thursday night into Friday since Friday and we so no reason to change the forecast at this point. J-Lo will have the latest information at 5:00 and 10:00 tonight and Sarah in the morning,

Before everyone freaks out, this does not appear to be anything like THE Ice Storm from 2009!

Stay tuned!

1 comment:

Anonymous said...

Thank you for the very last sentence of this post. You obviously understand some of us still feel traumatized over that ice storm. The term "freezing rain" will probably forever make my heart flutter and my stomach churn because of that storm.