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Mesoscale Discussion 159
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MD 159 graphic

   Mesoscale Discussion 0159
   NWS Storm Prediction Center Norman OK
   1119 AM CDT Tue Mar 20 2018

   Areas affected...Northern Maryland into southeastern Pennsylvania
   and New Jersey

   Concerning...Winter mixed precipitation 

   Valid 201619Z - 202015Z

   SUMMARY...Areas of moderate to heavy snow will develop across the
   discussion area, with rates will approach 1 inch per hour.  Freezing
   rain/sleet should also continue along the southern extent of the
   discussion area.

   DISCUSSION...Lift associated with a mid-level impulse centered over
   West Virginia has aided in areas of moderate to heavy snow over the
   past hour or so - especially along western and southern portions of
   the discussion area.  This area of precipitation should continue to
   develop northeastward across the remainder of the region and persist
   through at least 20Z.  Areas of dry low-level air were noted
   downstream of this precip shield (into southeastern Pennsylvania),
   although rapid moistening of the boundary layer and cooling surface
   temperatures (just below freezing) will encourage higher
   precipitation rates in that area shortly.  Rates approaching 1 inch
   per hour are possible through mid-afternoon.

   Farther southeast along an axis from central Maryland into New
   Jersey, slightly warmer low-level thermodynamic profiles are
   supporting a mixing of rain, freezing rain, and sleet.  This mixed
   precipitation should continue through 20Z and possibly beyond as a
   coastal low continues to organize southeast of the region.

   ..Cook.. 03/20/2018

   ...Please see for graphic product...


   LAT...LON   40037866 40287811 40417678 40487549 40467461 40277423
               39997411 39667428 39447496 39317624 39107734 39357800
               39627851 40037866 

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