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Mesoscale Discussion 186
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   Mesoscale Discussion 0186
   NWS Storm Prediction Center Norman OK
   0813 PM CST Thu Feb 24 2022

   Areas affected...Parts of PA...far northeastern WV...far northern
   VA...MD...and northern/western NJ

   Concerning...Winter mixed precipitation 

   Valid 250213Z - 250715Z

   SUMMARY...A mix of freezing rain and sleet will develop
   northeastward into the overnight hours.

   DISCUSSION...Latest water vapor imagery depicts a strong shortwave
   trough and accompanying midlevel speed maximum advancing eastward
   across parts of the Middle MS Valley. Ahead of the shortwave trough,
   surface observations show pressure falls being maximized in the OH
   vicinity, where a low pressure system will continue to develop over
   the next several hours. As the cyclone deepens, increasing southerly
   flow and related warm air advection will overspread the Central
   Appalachians and Mid-Atlantic states, resulting in a gradual
   increase in winter precipitation in the 03Z-08Z time frame.

   Across the southern and central portion of the discussion area, RAP
   forecast soundings show 850-mb temperatures increasing to 3-5 C atop
   a shallow subfreezing layer, which will favor complete melting of
   descending hydrometeors prior to refreezing near the surface. This
   will result in primarily freezing rain, with rates as high as 0.05
   in/hour owing to the strengthening forcing for ascent and deep-layer
   moistening. With northward extent, observations and forecast
   soundings show a deeper low-level subfreezing layer, with 850-mb
   temperatures near 1-3 C, indicative of partial melting of
   hydrometeors and the potential for sleet and freezing rain. 

   Farther north across northern PA, moderate snow is likely to develop
   where deeper cold air is in place, with an eventual increase in
   snowfall rates expanding northward into NY during the early morning

   ..Weinman.. 02/25/2022

   ...Please see for graphic product...


   LAT...LON   40047501 39717552 39247634 38697726 38367874 38827939
               39407941 40317951 40658032 41568010 42107955 41757732
               41307529 40837423 40557426 40047501 

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