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Mesoscale Discussion 133
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   Mesoscale Discussion 0133
   NWS Storm Prediction Center Norman OK
   0518 AM CST Thu Feb 27 2020

   Areas affected...northern New Hampshire through western Maine

   Concerning...Heavy snow 

   Valid 271118Z - 271615Z

   SUMMARY...Periods of moderate to heavy snow expected to expand
   northward from northern NH through western Maine this morning with
   rates locally exceeding 1 inch per hour at times.

   DISCUSSION...This morning water vapor imagery shows a negative-tilt
   shortwave trough across PA and NY moving northeast toward New
   England. The attendant surface low was situated over southeast NY
   with a warm front extending eastward off the coast of southern New
   England. A 50-60 kt southerly low-level jet coupled within the exit
   region of an upper jet streak is resulting in a broad corridor of
   strong and deep isentropic ascent north of the warm front. The
   resulting broad precipitation shield is rapidly expanding
   northeastward. Despite the very strong warm advection regime as
   evidenced by the strong veering and large hodographs within the
   lowest 3 km, both dynamic cooling associated with strong vertical
   motion as well as wet wet-bulb cooling should result in temperature
   profiles near and below freezing across western Maine. Some rain or
   sleet could mix with the snow at the onset, before profiles cool
   sufficiently to support a heavy wet snow. Strong and deep ascent
   will extend through layers supportive of dendritic growth for
   several hours before the mid-level dry slot arrives from the south
   toward mid day.

   ..Dial.. 02/27/2020

   ...Please see for graphic product...


   LAT...LON   45817036 46866966 46736889 45906850 45156941 44727024
               44387090 44167137 44747143 45017124 45227088 45817036 

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