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Mesoscale Discussion 126
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MD 126 graphic

   Mesoscale Discussion 0126
   NWS Storm Prediction Center Norman OK
   0301 PM CST Thu Feb 20 2020

   Areas affected...Parts of northeastern North Carolina and
   southeastern Virginia

   Concerning...Heavy snow 

   Valid 202101Z - 210000Z

   SUMMARY...Snow, occasionally at heavy rates near or in excess of 1
   inch per hour, appears increasingly probable within a corridor
   across the North Carolina piedmont into southeast
   Virginia/northeastern North Carolina Tidewater region by 6-7 PM EST.

   DISCUSSION...Large-scale ascent, downstream of a low-amplitude short
   wave trough digging into the lower Ohio Valley, is supporting a
   broad shield of precipitation now overspreading a stalled or slowly
   moving frontal zone extending across much of the Southeast.  With
   the continuing east-southeastward progression of the mid-level
   impulse, models indicate that a surface frontal wave will gradually
   deepen east of the Carolina coast through early evening, while
   lower/mid tropospheric frontogenesis intensifies across the southern
   Mid Atlantic Coast region.

   Across the North Carolina coastal plain into the Tidewater of
   northeastern North Carolina and southeastern Virgnia, the latest
   Rapid Refresh suggests that lift will become increasingly maximized
   in the mixed-phase layer supportive of large dendritic ice crystal
   growth.  While forecast soundings suggest that temperature profiles,
   particularly near the surface and perhaps within a layer between
   850-700 mb, are still marginal for snow reaching the surface across
   much of this corridor, modification is ongoing in response to
   evaporative cooling and melting of precipitation.  This will
   continue as precipitation persists and rates intensify.  

   Aided by the onset of diurnal boundary layer cooling, and perhaps
   weak low-level cold advection in the wake of the frontal wave, a
   transition to snow appears probable by 23-00Z, if not before, along
   a corridor extending from roughly the Raleigh NC metropolitan area
   into the Hampton Roads vicinity.  It appears that this probably will
   include general snow rates in excess of 1/2 inch per hour, with
   rates occasionally on the order of 1 inch per hour in one or more
   developing narrow heavier bands, which may continue into mid/late
   evening.

   ..Kerr.. 02/20/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...AKQ...MHX...RAH...RNK...

   LAT...LON   36067971 36477903 36987610 36177612 35457820 35407917
               36067971 

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