Re: JAC was right
Posted by Jackstraw on 1/30/2010, 4:13 am
This storm is a great example of a high pressure wedge or cold air damming up against the southern Appalachian's, something I really never understood until this year because it has been so persistent.  The freezing line right now is very pronounced roughly along I85 from NC to GA.  The cold air is heavy and and is being funneled down the backside of  surface high pressure over PA.  With lack of upper forcing and the density of the air it stacks up against the mountains and the surface high distorts, being "thinner" on it's southern side than on it's northern side, hence a "wedge".  With El Nino supplying moisture farther north via the sub tropical jet low pressure brings moisture up via a warm front but because of the heavy sinking cold air the warm moist air rises above it and creates great icing conditions over the lower piedmont of GA and SC.  But as it tries to move up the eastern side of the mountains the thickness of the warm sector thins and becomes more snow than freezing precip.  Right now there is a 40 mile difference between 10 in. of snow and rain.  If you've ever seen a graphical weather map of the SE and the warm front literally buckles to almost being S to N in orientation up the east side of the Appalachians this is what is happening.  It is also one of the hardest environments to forecast because vertical temperature profiles are very chaotic where the geography rises.  Anyway that's the way I understand.  It at least explains those funky looking weather maps I've seen
 16 inches of snow possible in Asheville NC again?    
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Major Winter Storm: OK to VA - JAC, 1/28/2010, 7:04 am
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