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20 January Short-range

Forecast valid 2:00pm EST - 20 Jan 2011
    Over the next three days there will be three focus points for the forecast.  Currently, there is a snow producing system moving through the region, stretching from the Ohio Valley Region to Arkansas.  This system will continue to move ENE will significant forcing and vertical motion support from positive vorticity advection and the upper level jet.  The increased strength and gradient of the jet provides upper level divergence leading to vertical motion.  As the system moves to the Northeast region it will continue to be supported by a significant jet and vorticity advection.  It's intensification will begin to be supported more by warm-air advection as it reaches the East Coast and has the possibility for explosive-cyclogenesis as it travels northeastward. 
    In our region, cold air will follow this system and will move south with a digging trough.  The building of high pressure is displayed in Lafayatte sounding valid at 18Z Friday with the subsidence inversion and dry conditions at the mid-levels.  Cold air advection means temperatures will plunge into the mid-10s as a high for Friday with winds around 10 knots supporting possible sub-zero windchills. 
    The third focus is on a short-wave clipper moving down from Canada during Saturday.  This has been a common occurence with the current pattern we have been experiencing for many weeks.  A ridge on the West Coast and a trough over the East Coast have directed these clipper-type systems down through the Midwest/Great Lakes Region and up through the Northeast on many occasions in the last month.  This will be repeated on a small scale on Saturday as a clipper will drop small amounts of snow over the Upper Great Plains and Great Lakes region, mainly supported by slight warm air advection in the area.  Vorticity and upper level jet support is minimal at best, but the warm air advection should be significant enough to support vertical motion and precipitation. Temperatures at all levels point to this system being an all snow event.  This short-term forecast ends with a mention of the possibility for significant precipitation event coming early next week. Mainly centered further south, the track of this system is worth paying attention to as it has the potential to be a significant precipitation event with a more northern track. 

today's short-range forecast graphic was produced by Kevin Van Leer
 

 

 
 
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