Sunday, January 30, 2011

Ice Storm Of The Century?

There are a lot of weather events that affect our country, but one is more dangerous then tornados and hurricanes combine and can cover a much larger area. No it's not a snowstorm, its a freezing rain event. Currently across NJ we are measuring snow depth in feet and Tuesday could bring us yet another 4"-8" on top. Bad news is trailing that storm a larger storm is tracking up the spine of the appalachians putting us on the warm side this time.

Looks like a rain event right? No. When you have a cold air mass in place across the east coast and a system like this rides up into it the cold air damns up against the eastern side of the mountains and can create havoc. This is called cold air damning.

In the above figure you can see the warm air riding over top the cold air, this is called an inversion. The cold air is trapped by the mountains because it is more dense and settles to the surface, this set up is typical of the La Nina pattern. This can be seen in the atmospheric soundings as well. The yellow line is freezing and the blue lines are temperature and dew point. The inversion here is clear at the point where the blue lines pass through the yellow line. This sounding supports freezing rain/sleet in Sussex County NJ.

Let's keep an eye on this one....

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